Technological and quality effects of partial sodium replacement with potassium and calcium chlorides in traditionally fermented green Nabali Baladi table olives (Olea europaea L.)

Efeitos tecnológicos e de qualidade da substituição parcial de sódio por cloretos de potássio e cálcio em azeitonas verdes tradicionalmente fermentadas da cultivar Nabali Baladi (Olea europaea L.)

Abstract

This study evaluated the viability and quality effects of partially replacing sodium chloride with potassium and calcium chlorides in traditionally fermented green Nabali Baladi table olives (Olea europaea L.). Five mineral salt formulations of olives were fermented for 180 days and observed. To assess potential effects of salt substitution on fermentation and fermentation quality, water activity, pH evolution, texture, bioactive compounds, mineral composition, and sensory characteristics were compared. Reformulated brines had slightly higher water activity values (0.947–0.958) than that of the NaCl control (0.942), but fermentation in each treatment was normal and steady in all treatments, and this was indicated by increasing acidification indicating stable fermentation. Texture markedly decreased during fermentation, and the puncture strength decreased from around 16.7 N to 9.1–11.5 N, and CaCl₂-containing brines had a higher firmness at later stages (higher than conventional brine). The bioactive compounds decreased with progression; compound-dependent reduction (≈15–70%) was observed, but a mixed salt type formulation resulted in enhanced phenolic retention in later stages of treatment. Mineral content analysis showed a substantial decrease in sodium content (1320 to 122 mg/100 g) and significant increases in potassium (up to 604 mg/100 g) and calcium (up to 475 mg/100 g), showing that there is effective ion exchange between olives and brines. Through sensory evaluations, a stronger bitterness was observed in the solutions containing KCl and enhanced texture in CaCl₂ formulations; however, mixed-salt formulations showed the most balanced sensory characteristics. In general, the integrated NaCl/KCl/CaCl₂ brines represent a strong solution towards sodium reduction coupled with the preservation of fermentation performance, nutritional quality, and sensory acceptability.

Keywords:
Nabali Baladi olives; sodium reduction; mineral salt substitution; fermentation; bioactive compounds; sensory quality

Resumo

Este estudo avaliou a viabilidade e os efeitos de qualidade da substituição parcial de cloreto de sódio por cloretos de potássio e cálcio em azeitonas verdes tradicionalmente fermentadas da cultivar Nabali Baladi (Olea europaea L.). Cinco formulações de sais minerais para azeitonas foram fermentadas por 180 dias e monitoradas Para avaliar os potenciais efeitos da substituição de sal na fermentação e na qualidade final, foram comparadas a atividade da água, a evolução do pH, a textura, os compostos bioativos, a composição mineral e as características sensoriais. As salmouras reformuladas apresentaram valores de atividade da água ligeiramente superiores (0,947–0,958) em relação aos do controle com NaCl (0,942), mas a fermentação em cada tratamento foi normal e estável em todos os tratamentos, o que foi indicado pelo aumento da acidificação, indicando uma fermentação estável. A textura diminuiu acentuadamente durante a fermentação, e a força de punção reduziu de cerca de 16,7 N para 9,1–11,5 N. As salmouras contendo CaCl₂ apresentaram maior firmeza nos estágios finais (superior à salmoura convencional). Os compostos bioativos diminuíram com a progressão do processo; observou-se uma redução dependente do composto (≈15–70%), mas uma formulação com sais mistos resultou em maior retenção de compostos fenólicos nos estágios finais do tratamento. A análise do conteúdo mineral mostrou uma diminuição substancial no teor de sódio (de 1320 para 122 mg/100 g) e aumentos significativos nos teores de potássio (até 604 mg/100 g) e cálcio (até 475 mg/100 g), demonstrando que houve troca iônica eficaz entre as azeitonas e as salmouras. Por meio de avaliações sensoriais, observou-se um amargor mais intenso nas soluções contendo KCl e uma textura aprimorada nas formulações com CaCl₂; no entanto, as formulações com sais mistos apresentaram as características sensoriais mais equilibradas. Em geral, as salmouras integradas NaCl/KCl/CaCl₂ representam uma alternativa promissora para a redução de sódio, aliada à preservação do desempenho da fermentação, da qualidade nutricional e da aceitabilidade sensorial.

Palavras-chave:
azeitonas Nabali Baladi; redução de sódio; substituição de sais minerais; fermentação; compostos bioativos; qualidade sensorial

1. Introduction

Among the earliest cultivars, olive trees ((Olea europaea L.) began growing in the Mediterranean and Middle Eastern regions, where at the present day, they remain an essential part of many local diets (Ghanbari et al., 2012). A number of countries have expanded their olive production beyond the Mediterranean basin, including the United States, Argentina, Peru, and Australia, despite the fact that the Mediterranean basin still dominates the production of olives around the world (Dalloul and Erten, 2018; Ghanbari et al., 2012). A significant part of Jordan's culture and economy is achieved through olives: about 80% are used to extract oil from the trees and 20% are fermented into table olives (Jordan, 2016). In 2016, national table olive consumption reached 28,000 tons, which accounted for about 10% of global table olive consumption (Jordan, 2016). On the nutritional side of things, olives are rich in fibers, proteins, vitamins, minerals, phytosterols, pigments, and polyphenolic compounds in addition to monounsaturated oleic acid, which is the primary monounsaturated fat found in olives. Many of these components contribute to health-promoting effects, including antioxidants, antimicrobials, antihypertensives, anti-inflammatory agents, and anticarcinogenic (Lanza et al., 2010).

In 2019/2020, global table olive consumption was approximately 3.0 × 10⁶ tons, making olives the most widely consumed fermented fruit (IOC, 2022). Among the various varieties of olives grown in Jordan, the Nabali Baladi cultivar dominates as it is well adapted to the dry climate there, and at the same time serves as an oil product as well as a table olive (Al-Ismail et al., 2011; Humeid et al., 1991). As fermentation is usually carried out in brine, sodium chloride (NaCl) plays a major role in the safety of the fermentation process, as well as the texture and sensory attributes of the product (Fernández et al., 1997). Olive brines typically contain around 8% NaCl, with the concentration later lowered to 5–6% for natural olives or treated olives and up to 10% for dehydrated olives (Fernández et al., 1997; IOC, 2004). Traditionally, Jordanian olives are fermented by depositing them in water for three days, followed by their natural fermentation in high-salt brine solution, resulting in the creation of a unique flavor profile compared to those produced by the Greek, Italian, or Spanish cultures (Bleve et al., 2014). A variety of beneficial microorganisms, including lactic acid bacteria (LAB) and yeast, help to promote spontaneous fermentation, resulting in flavors, textures, and phytochemicals being released into the food (Bleve et al., 2014). Even though NaCl is an important technical formulation, fermented olives have a health risk associated with it. High sodium intake is strongly associated with hypertension and cardiovascular disease (Wang et al., 2020). According to a meta-analysis of 36 studies that involved over 616,000 participants, people with a high sodium intake had 19% higher chances of getting cardiovascular disease, with the risk increasing by 6% for every additional gram of sodium consumed each day (Wang et al., 2020). It is recommended by public health guidelines that sodium intake should be limited to 2.3–2.4 grams per day (European Union, 2011; USDA, 2020). Since table olives can be considered a significant source of sodium (Lopez et al., 2008; Lopez-Lopez et al., 2023), consumption and production have both become committed to reducing sodium levels during fermentation.

Research has investigated reducing brine concentrations (Özay and Borcakh, 1995; Tassou et al., 2002) and partially substituting alternative salts for NaCl to address this issue. It has been shown that potassium chloride (KCl) can perform some of NaCl's functions with minimal changes in sensory perception (Özay and Borcakh, 1995; Tassou et al., 2002; Dalloul and Erten, 2018). Some recent publications also claim that KCl can be successfully substituted for sodium reduction in table olive brines in some formulation without affecting product quality (Chata et al., 2024), while calcium chloride (CaCl₂) is capable of improving pulp firmness and texture but may cause bitterness at higher concentrations (Tassou et al.,2007; Bautista-Gallego et al., 2010; Panagou et al., 2011). Several mixed salt approaches have demonstrated promising results in terms of microbial stability, acidification, and product quality (Kanavouras et al., 2005; tsa, Bautista-Gallego et al., 2010; Panagou et al., 2011; Dalloul and Erten, 2018). Recent evidence on Nabali Baladi olives further supports the feasibility of mineral salt substitution strategies. Specifically, partial replacement of NaCl with KCl has been shown to preserve fermentation performance while reducing sodium and enriching potassium without compromising physicochemical stability (Othman et al., 2026). Changing salt composition will affect microbial ecology, which in turn can impact fermentation dynamics and ultimately affect nutrition and function of the final product (Ambra et al., 2017; Bautista-Gallego et al., 2015; Pires-Cabral et al., 2018). A diet low in sodium and rich in potassium (K) and calcium (Ca) is recommended for reducing blood pressure (Tassou et al., 2002), while calcium also provides protection against osteoporosis and colon cancer (Kanavouras et al., 2005). Low sodium consumption and high potassium and calcium intake have been proven to lower blood pressure (Tassou et al., 2002; Kanavouras et al., 2005), while calcium also protects against osteoporosis and colon cancer. The European Union allows minerals to be included in fortified foods (Directive, 2002/46/CE). By replacing Na with K and Ca in table olives, we might be able to gain additional health benefits (Tassou et al., 2007). Studies in traditionally fermented Nabali Baladi olives have demonstrated that the partial replacement of NaCl with KCl could change microbial ecology, sodium/potassium content, phenolic compounds, antioxidant activity, and sensory quality (Othman et al., 2026). The combined use of KCl and CaCl₂ and its influence on texture, mineral enrichment, bioactive compound retention, and sensory properties in Nabali Baladi olives were not yet adequately studied. These results could be studied to help form the understanding that could provide the way to the nutritional improvements of table olives without negatively affecting their technological integrity and sensory attributes. Most of the research has concentrated on European and Turkish olive types, with relatively little emphasis on the Jordanian traditional fermentation practices, particularly on the technological performance and sensory properties of olives. Previous studies had explored sodium replacement techniques in olive cultivars from Europe and Turkey, but information on Jordanian cultivars is scarce. More specifically, no prior research has extensively studied the synergistic effects of NaCl substitution with KCl and CaCl₂ on fermentation behavior, texture development, bioactive compound retention, mineral composition, and sensory quality of traditionally fermented green Nabali Baladi olives. Thus, this research presents new insights on the technological and quality aspects of mineral salt substitution under traditional Jordanian fermentation conditions.

2. Materials and Methods

2.1. Samples and experimental design

Fresh green Nabali Baladi olives were acquired directly from a farm in Jerash, Jordan. The salts were purchased at a local market that sells food grade NaCl, KCl, and CaCl₂. The green Nabali Baladi olives were fermented according to the traditional Jordanian method (Ahmad et al., 2021). Mechanical pressure was used to create a cut inside the olive flesh in order for brine solutions to settle inside the olive. Then, a three-day immersion of the crushed olives in water followed to remove the bitterness. The olives were fermented in five different brines of different chloride salt concentrations: 10% NaCl (Brine A), 5% NaCl+5% KCl (Brine B), 5% NaCl+5% CaCl₂ (Brine C), 5% KCl+5% CaCl₂ (Brine D) and 3.33% NaCl+3.33% KCl+3.33% CaCl₂ (Brine E). The sodium condition (with 10% sodium chloride treatment) was applied as control (Table 1). Brine solution was brought into plastic containers by weighing 45 kg of olive fruit. A spontaneous fermentation was performed at 25°C in triplicate for a maximum of 180 days, while the chloride salt concentration in brines was kept at 10%. During the fermentation stage, brine pH was measured, and the effects of brine of different concentrations were measured at 0, 90 and 180 days intervals. At the end of the study, 6 months after storage, olives were also subjected to sensory tests.

Table 1
Various salt concentrations (wt/vol%) in brine used to produce green Nabali Baladi olives.

Brines	[NaCl] (%)	[KCl] (%)	[CaCl2] (%)	[Total] (%)	Initial aw
1	10	0	0	10	0.9417 ± 0.0025
2	5	5	0	10	0.9473 ± 0.0015
3	5	0	5	10	0.9490 ± 0.0010
4	0	5	5	10	0.9580 ± 0.0044
5	3.33	3.33	3.33	10	0.9530 ± 0.0026

• NaCl = sodium chloride; KCl = potassium chloride; CaCl₂ = calcium chloride; w = weight (g); v = volume (mL); a_w = water activity. a_w is followed by standard error.

2.2. Physicochemical analysis

a_w was measured using an AquaLab Pre apparatus (Meter Group Inc., WA, USA) at 25 °C for each treatment after preparation of the initial brines. Table 1 shows average values obtained after combining salts in each run. pH in each of the olive jars was measured during the course of fermentation with a Crison Basis 20 pH-meter (Barcelona, Spain) at 0, 30, 60, 90, 120, 150, 180 days interval. Each measurement was performed in triplicate.

2.3. Chemical analysis

At first the olives were put into liquid nitrogen, and then they were frozen. This process facilitated easier pulverization. The frozen olives were subsequently ground into a fine powder through an IKA A 11 Basic analytical mill (IKA, Staufen, Germany), allowing for a uniform texture for precise chemical analyses. This process stored the powder at −80°C until later analysis. During processing, olives were kept at +4°C for sensory and texture characteristics. Texture was analyzed according to Kavdir et al. (2009) performed for fifteen drupes per sample via the penetrometer (TA.XT2, Texture Technologies Corp., New York, NY, USA) equipped with a 3 mm diameter tip, at 5 mm s⁻¹ speed approximately 3 mm deep into the pulp. Texture data were represented by the strength at the time of the puncture. Analysis of sodium, potassium and calcium was performed using an atomic absorption spectrometer (AAnalyst 400, PerkinElmer, Waltham, MA, USA) and standards were obtained from Sigma-Aldrich according to the AOAC method (AOAC, 2002) which states that after they underwent mineralisation (1 g per sample, 525 °C for 16 h, solubilized in 1 mL HNO3 65% and to a final volume of 50 mL HNO3 1% (v/v) + 0.1% (w/v) CsCl to avoid sodium, potassium and calcium ionization. Tocopherols, carotenoids and squalene were analysed by HPLC-DAD an Agilent 1100 series (Santa Clara, CA, USA). Extraction protocol of this work according to Miraliakbari and Shahidi (2008), consisted of putting 5 g of frozen olive powder placed in screw-capped tubes containing 20 mL of methanol/chloroform (1:1 v/v) and then shaken for 20 min time with an orbital shaker at 300 rpm (Thermo Fisher Scientific, Waltham, MA, USA). Extraction method methanol/chloroform extraction for effectiveness of extraction was iteratively tested. Extracts were collected and evaporated to dryness under vacuum (40 °C), and the residue dissolved in 2 mL of methanol/chloroform (1:1 v/v). After filtration (0.2 µm), an aliquot of 20 µL was injected into the HPLC. HPLC was equipped with a Cosmosil 5PYE (Nacalai, Kyoto, Japan) reversed-phase column (4.6 ID × 250 mm) for evaluation of tocopherols and squalene; the mobile phase was methanol/water (95:5 v/v) that was run isocratically at 30 °C at a flow of 1 mL min⁻¹. The detection was performed using a wavelength of 292 nm. The carotenoids were processed by placing them in a YMC C30 (YMC, Kyoto, Japan) column (4.6 ID × 250 mm) at 35 °C at a flow of 1 mL min⁻¹ consisting of (A) methanol/acetone 60:40 v/v and (B) acetone/water 60:40 v/v using the same gradient (44 min): 70% A for 3 minutes, 90% A for 5 minutes, 95% A for 17 minutes, 100% A for 10 minutes. Detection was run at a wavelength of 450 nm. Tocopherols, carotenoids, and squalene were distinguished by their retention times and spectra versus those of standards from Sigma-Aldrich when run under identical conditions (Cayman Chemical (Ann Arbor, MI, USA)). Phenolic compounds were extracted twice from 2 g of frozen powder by shaking in 20 mL ethanol/water 80:20 containing 0.2% sodium metabisulphite for 10 min, using an orbital shaker (Thermo Fisher Scientific, Waltham, MA, USA), running at 300 rpm. To this mixture, the extracts were defatted twice with 10 mL hexane by shaking for 10 min at the same speed. Hydrophilic extracts were then separated by centrifugation for 5 min and evaporated to dryness under vacuum (40 °C) (adapted from Artajo et al., 2006). The dry residue was redissolved in 2 mL with methanol/water (1:1 v/v), filtered (0.2 µm) and then injected in HPLC (20 µL). Phenolic compounds were separated from a Kinetex 2.6u PFP 100A (Phenomenex, Torrance, CA, USA) column (4.6 ID × 100 mm) at 48 °C with a flow of 1.85 mL min⁻¹. Mobile phase (A) included 1.2 mL per 100 mL acetic acid in water and (B) methanol, running with the following gradient (45 min): 95% A for 3 min, 85% A for 11 min, 75% A for 6 min, 55% A for 8 min. DAD was set at 278 nm.

2.4. Sensory evaluation

Sensory evaluation was a consumer hedonic test in accordance with ISO 13229 (ISO, 2010) and was intended to measure consumer liking and perception of relevant sensory attributes, rather than employing a trained descriptive analysis. The sensory analysis was performed 180 days following fermentation process. A panel of 60 untrained volunteer panelists (aged 18–65 years; 36 females, 24 males) were recruited from faculty staff and undergraduate students at the Faculty of Applied Medical Sciences at Al-Balqa Applied University. All panelists reported consuming olives on a regular basis, since table olives are a traditional product in Jordan. Panelists rated the samples on a 9-point hedonic scale from 1 (dislike extremely) to 9 (like extremely). This was a consumer test and therefore panelists were not trained on IOC descriptive panel standards by comparing attributes. Rather, prior to performance they received verbal instructions and reference descriptions on the dimensions of each condition in order to ensure a common understanding of sensory terms and how the scales were used. Pulp separation was scored as a texture preference trait representing panelists’ perception of the ease of removing the olive pulp from the stone during mastication, rather than as a mechanical-physical separability feature. Although cracking promotes pulp separation, differences in fermentation conditions, brine ionic composition, and softening of tissue were anticipated to affect this perception even for cracked olives, so the hedonic scale measured preference associated with pulp separation. Texture perception was also defined using hardness and cohesiveness as separate attributes, with hardness defined as the force needed during the first bite and cohesiveness as the degree of pulp integrity during mastication without it breaking or becoming pasty. Panelists were encouraged to categorize these features according to the timing in which texture was perceived, with hardness measured at first bite and cohesiveness during chewing and explained in short verbal explanations and oral examples. The flavor profile of olive was added to represent the generic flavor of fermented olives, including retro nasal aroma and integrated taste perception instead of discrete simple flavors (e.g. bitterness, saltiness), as often carried out in consumer sensory studies. Although olives are inherently bitter, sweetness was added as a sensory parameter as a proxy for subtle differences in flavor balance related to fermentation, since diffusion of sugar from the pulp and organic acid production might affect bitterness suppression and general acceptance. These low sweetness scores generally found were thought to be true for the typical sensory profile of fermented olives and thus lend support to the validity of the assessment.

2.5. Statistical analysis

Measurements all had mean ± standard deviation (SD) values. Two-way ANOVA analysis on values during fermentation (texture and bioactive compounds) was performed with fermentation time (0, 90, and 180 days) and brine composition (five formulations) as fixed factors (time × brine interaction). Post-hoc comparisons were performed (Tukey’s HSD test α = 0.05) where significant main effects and/or interactions were established. The end-point mineral composition data (measured only at the end of fermentation) were determined through a one-way ANOVA using brine formulation as the fixed factor and Tukey’s HSD test (α = 0.05). Differences in pH during fermentation (Figure 1) are shown as mean ± SD during each period for every brine formulation. Sensory data using a 9-point hedonic scale were analyzed using one-way ANOVA (with brine formulation being the fixed factor for each sensory attribute), Tukey’s HSD test (α=0.05), and visualized with radar plot analysis. Tested for normality and homogeneity of variance, ANOVA assumptions were handled by residual diagnostics. Statistical analysis of SPSS 23 software (IBM SPSS Statistics, NY, USA) was used for analysis, and significance is set to α=0.05.

Figure 1
Changes in pH during the 180-day fermentation of green Nabali Baladi olives in five brine formulations containing different proportions of NaCl, KCl, and CaCl₂. Values are presented as mean ± SD.

3. Results

There were clear and statistically significant differences between the brine formulation and their a_w values in fermented olives (Table 1). The lowest a_w values were always noted in the olives fermented within the 100% NaCl control, while elevations in a_w values were observed in all reformulated brines containing potassium and/or calcium salts. Out of these, combined KCl and CaCl₂ brines demonstrated the highest a_w values and intermediate values were obtained in brines with single salt substitutions. Despite variations across treatments, the a_w values tended to be within range, and all treatments fall within limits for controlled olive fermentation. Figure 1 displays changes in pH during fermentation. For all brine formulations, pH reduced progressively from the start of fermentation to the end of the storage period and is an indicator of the achievement of acidification. pH had the greatest drop in early fermentation and decrease gradually from early fermentation toward late time points. While all treatments were consistent in terms of overall pattern, a variation was observed in change in the rate and extent of reduction of pH between different brine formulations, with some substituted brine holding slightly higher pH values than did 100% NaCl control with the latter stages of fermentation.

Fermentation texture evolution is detailed in Table 2. Puncture strength values exhibited a gradual decline from day 0 to day 180 for the brine formulations, corroborating a prevailing softening effect during fermentation. Early stage (day 0), Puncture strength values were similar between different treatments, while the differences between treatments were not significant. As fermentation matured, the brine formulations were differentiated. Firmness values were highest for olives fermented in CaCl₂ containing brines both 90 and 180 days and lowest for those fermented in KCl-based brines. The firmness of 100% NaCl control was intermediate. 2-way ANOVA results indicated that the fermentation time, brine composition and their interaction had a significant impact on texture (P < 0.001).

Table 2
Texture of olives expressed as the strength (N) measured at the moment of puncture (mean ± SD).

Brine composition	Time 0 (N)	90 days (N)	180 days (N)
100% NaCl (0% KCl, 0% CaCl2)	16.67 ± 0.06ᵃ	11.27 ± 0.15ᵇ	9.13 ± 0.21ᶜ
5% NaCl + 5% KCl	16.67 ± 0.06ᵃ	11.57 ± 0.06ᵇ	9.10 ± 0.36ᶜ
5% NaCl + 5% CaCl2	16.70 ± 0.00ᵃ	11.87 ± 0.21ᵇ	10.40 ± 0.26ᵇ
5% KCl + 5% CaCl2	16.70 ± 0.00ᵃ	12.30 ± 0.10ᵃ	11.53 ± 0.31ᵃ
3.33% NaCl + 3.33% KCl + 3.33% CaCl2	16.70 ± 0.00ᵃ	11.47 ± 0.21ᵇ	9.63 ± 0.64ᶜ

• Values are expressed as mean ± SD. Different superscript letters (a–c) within the same row indicate significant differences among fermentation times according to Tukey's HSD test (P < 0.05). Data were analyzed by two-way ANOVA considering fermentation time and brine composition as fixed factors. Time effect: P < 0.001; Brine composition effect: P < 0.001; Time × Brine interaction: P < 0.001.

The bioactive compound evolution during fermentation is given in Table 3. In all treatments concentrations of α-tocopherol, β-carotene, squalene and total phenolic compounds continuously decreased during the fermentation period. The largest reductions (for all compounds) recorded occurred from day 0 to day 180. Fermentation time was significantly and highly influential for all bioactive compounds (P < 0.001). Modifications within brine formulations were compound dependent. For phenolic compounds, marked differences for treatments appeared in 90 and 180 days, as olives fermented in mixed salt brines showed larger residual phenolic contents in comparison to NaCl control. In contrast, the differences of α-tocopherol and squalene contents were reduced between the various brine formulations, especially at the precursors of fermentation, thereby suggesting a limited range of salinity response.

Table 3
Amount of bioactive molecules of fermented olives in 5 different brine solutions at the beginning and the end of fermenting process according to the composition of the brine (Mean ± SD).

Bioactive molecules	Fermentation Time	10% NaCl	5% NaCl 5% KCl	5% NaCl 5% CaCl2	5% KCl 5% CaCl2	3.33 NaCl 3.33 KCl 3.33 CaCl2	2 Way ANOVA
							Time	Brine	interaction
α-Tocopherol (mg/g)	Time 0	6.50 ± 0.00	6.50 ± 0.00	6.50 ± 0.00	6.50 ± 0.00	6.50 ± 0.00	P < 0.001	P < 0.001)	Ns
	90 days	6.40 ± 0.00	6.40 ± 0.20	6.13 ± 0.21	5.80 ± 0.20	5.57 ± 0.51
	180 days	6.43 ± 0.25	6.20 ± 0.56	5.90 ± 0.36	5.83 ± 0.35	5.33 ± 0.46
β-Carotene (mg/g)	Time 0	0.37 ± 0.00	0.37 ± 0.00	0.37 ± 0.00	0.37 ± 0.00	0.37 ± 0.00	P < 0.001	P < 0.01	P < 0.001
	90 days	0.23 ± 0.06	0.20 ± 0.03	0.18 ± 0.04	0.21 ± 0.04	0.19 ± 0.02
	180 days	0.21 ± 0.03	0.16 ± 0.04	0.13 ± 0.02	0.10 ± 0.02	0.25 ± 0.03
Squalene (mg/g)	Time 0	148.00 ± 0.00	148.00 ± 0.00	148.00 ± 0.00	148.00 ± 0.00	148.00 ± 0.00	P < 0.001	P < 0.001	P < 0.001
	90 days	153.67 ± 3.51	139.67 ± 4.04	132.00 ± 4.00	117.00 ± 5.00	128.00 ± 4.00
	180 days	121.00 ± 3.61	108.33 ± 8.62	105.00 ± 8.72	90.00 ± 3.61	105.00 ± 5.00
Phenolic compounds (mg/g)	Time 0	13.82 ± 0.00	13.82 ± 0.00	13.82 ± 0.00	13.82 ± 0.00	13.82 ± 0.00	P < 0.001	P < 0.001	P < 0.001
	90 days	11.87 ± 0.46	17.30 ± 0.36	14.57 ± 0.25	13.73 ± 0.40	15.57 ± 0.25
	180 days	11.57 ± 0.35	22.37 ± 0.59	15.27 ± 0.31	14.17 ± 0.21	16.97 ± 0.21

• Values are expressed as mean ± SD. Data was analyzed by two-way ANOVA considering time and brine composition as fixed factors. Ns = not significant.

Mineral composition of fermented olives (at the end of fermentation) is presented in Table 4. Sodium content differed significantly between treatments, with olives fermented in the 100% NaCl control receiving the highest level of sodium concentration. Treatment-induced sodium levels were the lowest in all reformulated brines, with treatment with the highest NaCl replacement intensity yielding the lowest levels. On the other hand, the concentrations of potassium and calcium also increased in combination with their contents in fermentation brines. Olives fermented with KCl-containing brines contained the highest concentration of potassium, whereas the highest concentration of calcium was collected by the fermentation with CaCl₂ containing brines. Significant values were found for all treatments based on sodium, potassium, and calcium contents (P < 0.05).

Table 4
Sodium, potassium, and calcium content of olives at the end of fermentation under different brine compositions.

Brine composition	Sodium (mg/100 g)	Potassium (mg/100 g)	Calcium (mg/100 g)
100% NaCl (0% KCl, 0% CaCl2)	1320.3 ± 4.2ᵃ	103.7 ± 5.5ᵉ	50.3 ± 2.5ᶜ
5% NaCl + 5% KCl	780.3 ± 4.2ᶜ	604.0 ± 6.2ᵃ	49.7 ± 3.8ᶜ
5% NaCl + 5% CaCl2	803.7 ± 5.7ᵇ	93.3 ± 4.5ᵉ	475.3 ± 5.0ᵃ
5% KCl + 5% CaCl2	121.7 ± 6.7ᵉ	540.7 ± 4.0ᵇ	420.3 ± 5.0ᵇ
3.33% NaCl + 3.33% KCl + 3.33% CaCl2	561.0 ± 3.6ᵈ	393.0 ± 4.4ᶜ	388.0 ± 9.8ᵇ

• Values are expressed as mean ± SD. Different superscript letters (a–e) within the same column indicate significant differences among brine formulations according to Tukey's HSD test (P < 0.05).

Fermented olives sensory properties are displayed in Figure 2. For brine formulations, distinct sensory profiles were seen. KCl-containing brine fermented olives had the highest bitterness and aftertaste scores, while the most texture-related scores came from a CaCl₂-containing brine fermentation process. Saltiness was highest for 100% NaCl control and lowest for all reformulated treatments. Most attributes rated mixed-salt formulations intermediate in sensory performance: low in bitterness but high in texture performance.

Figure 2
Radar diagram showing sensory attributes of fermented olives processed with different chloride salts.

4. Discussion

The present work presents an integrated technological evaluation of partial sodium replacement on fermented table olives and demonstrates that mineral salt reformulation affects fermentation activity, structural stability, chemical ingredients and sensory perception. In summary, the results show that sodium reduction by KCl and CaCl₂ is technically possible; however, to achieve desired product quality, proper choice and arrangement of mineral salts is essential.

In spite of the observed greater water activity compared to NaCl-only formulations (Table 1) in brines containing potassium and calcium salts, these differences could be explained according to well-known differences in water–solute interactions and the ionic strength of salts and salt mixtures. Although osmotic pressure was not measured here specifically, it is common for osmotic-driven mass transfer and water availability to be affected by the ionic composition of the brine in fermented vegetables, altering diffusion between brine and plant tissue. In this specific context, any partial replacement of NaCl with KCl and/or CaCl₂ might influence the olive–brine equilibrium and lead to variations in aᵥ values which correlate with previous evidence on reduced-sodium olive fermentations and related fermented vegetables (Ambra et al., 2017; Panagou et al., 2011). Of note, even though there was greater formation of aᵥ when using the reformulated brines, the spread between treatments was limited, indicating that salt replacement changed the availability of water without major degradation of the fermentation environment. The fermentation was conducted as before in all applications implying that salt concentration, acidification and microbial competition alone and in combination were required to stabilize fermentation as reported for controlled fermentation of olive (Panagou et al., 2008). As displayed in Figure 1 (pH), an appreciable reduction in pH over the course of all brine formulations affirms effective acidification (highly characteristic of well-performed olive fermentation). The steep decrease in pH at the early stage of the fermentation indicates active metabolism of fermentation microorganisms and the large amount of organic acids are rapidly produced, but a more gradual reduction is observed at later stages of fermentation. Treatments showed generally similar acidification characteristics; however, with slightly increased pH values observed in some of the substituted brines at later times, salt composition may affect the kinetics of fermentation. Partial replacement of NaCl with KCl and CaCl₂ may impact the growth dynamics of microbial organisms and/or the buffering capability of the brine allowing for greater acid development. However, final pH values were still within acceptable ranges for the microbiological stability of fermented olives and highlighted that replacing mineral salts did not affect fermentation efficacy. It has been found that acidification profiles were influenced by modified salt systems in low-sodium olive fermentations (but not sufficient to inhibit a fermentation outcome) with similar pH properties (Panagou et al., 2011; Bautista-Gallego et al., 2015; Ambra et al., 2017).

The fermentation resulted in strong time dependent changes in texture, which supports tissue softening as a basic property of olive fermentation (Table 2). No significant firmness differences can be observed between treatments at day 0; suggests that texture variation occurred during fermentation rather than during raw materials initial changes. The strong interaction time × brine implies a corresponding influence on the softening magnitude as a function of brine composition, in that systems containing CaCl₂ inhibit firmness attenuation during longer fermentation time. The enhanced firmness retention of brine with calcium is in agreement with the evidence of the reported activity of calcium in plant tissues. Calcium is one of the most widely used firming agents in plant foods as it can interact with pectic material for the formation of calcium pectate and strengthen the structure of cell wall and/or middle lamella and thus improve tissue firmness-to-cell adhesion and mechanical resistance (Romeo et al., 2009; Silveira et al., 2011). This mechanism explains the prominent value of the puncture strength in calcium formulations in 90 and 180 days. Substitution with KCl by itself was not enough to remove the texture loss, indicating that potassium ions present no comparable structural reinforcement. Similar scenarios have occurred with table olives and other table pickled vegetables, with calcium salts reducing softening, whereas potassium salts improved the balance of minerals even though the structure was not reinforced (Ambra et al., 2017; Bautista-Gallego et al., 2010).

The gradual diminution of bioactive compounds during fermentation (Table 3) was in accordance with studies showing that the most important factor influencing bioactive stability was fermentation time (Ambra et al., 2017, Rodríguez-Gómez et al., 2014). The reduction of α-tocopherol and squalene was significantly time-dependent and is most likely associated with oxidative degradation along with diffusion into the brine under prolonged processing situations, which are sensitive to oxygen delivery and tissue decay. Both α-tocopherol and squalene showed less formulation variations compared with phenolic compounds, showing that their degradation was primarily related to processing period and exposure conditions and had less dependence on salt composition alone. Phenolic compounds would be more sensitive to brine composition (especially in late fermentation events). However, in the same study, phenolic retention was higher in mixed-salt formulations than in the NaCl-only brines, suggesting that salt substitutes can partially adjust the diffusion and stability of phenolics during fermentation. Similar findings were also consistent with the current results: while the time of fermentation was the main factor to the degradation of bioactive compounds, mixed salt formulations might promote phenolic retention at later fermentation stages (Othman et al., 2026). As phenolic compounds may engage ion and cell wall in cross dialogue, perturbation in ionic strength and gradients in the olive–brine medium can influence their leaching into brine (Rodríguez-Gómez et al., 2014). Moreover, the antioxidant potential and sensory characteristics (e.g., bitterness, pungency) have potential to be positively associated with improved retention, thus providing yet another technological advantage of optimized salt mixes.

Mineral analysis of olives and brines confirmed ion exchange (Table 4), and sodium content was significantly reduced in aliquots of reformulated treatments. The gradual decrease in sodium content with increasing NaCl replacement forms the basis of a dose-dependent transfer from the brine to the olive cell. Potassium and calcium enrichment of olives are congruent with earlier reports on sodium-lower olive ferments and may also be used to inform usage of mineral salt substitution as an intervention for the reduction of sodium (Lopez-Lopez et al., 2016; Ambra et al., 2017). This ion exchange principle has also been well established in Nabali Baladi olives, where reductions of sodium content were significantly associated with increases in potassium and calcium levels, validating the successful use of mineral salt substitute strategies for nutrition (Othman et al., 2026). From a nutritional standpoint, one can contemplate this redistribution of food from the two mineral sources based on recommendation to reduce sodium intake and add more potassium and calcium intake. Importantly, these adjustments did not degrade fermentation performance, indicating that technical and nutrient targets are not mutually exclusive.

Sensory testing (Figure 2, sensory radar) further substantiated practical implications of salt substitution. Anticipated KCl preparations will exhibit heightened bitterness and aftertaste as potassium salts have a potential to enhance bitterness perception, demonstrating an accepted disadvantage of KCl-containing salt reduction (Sinopoli and Lawless, 2012). Similar to the reformulation goal, NaCl control provided the highest perceived saltiness while substituted formulations achieved a decreased sensibly salty level, demonstrating the demand for a tradeoff between sodium reduction and tactile sensibility. On the contrary, the texture perception had the best performance in brines with CaCl₂ added, verifying instrumental measurement information further, and further demonstrating the link between physicochemical structure and quality of the senses. In fact, mixed-salt formulations yielded the most balanced responses with respect to sensory properties, lowering the bitterness of KCl while preserving the textural properties of calcium, confirming previous studies indicating that the combined salt systems are superior to single alternatives in reduced-sodium fermented products (Ambra et al., 2017). Overall, these results suggest that replacing NaCl by KCl and CaCl₂ alone presents a technologically feasible approach to produce low-salt fermented olives, for which calcium preserves tissue integrity, potassium aids in reducing sodium (with flavor losses) and mixed salt provides the strongest combination of technological, nutritional and sensory advantages. Previous studies in Gemlik black olives also indicated that low-sodium olives can easily be acquired to desirable standards when NaCl is replaced by KCl, and when CaCl₂ was used in the preparation, the observed bitterness and preference was enhanced (Erdogan et al., 2018). However, the present study has limitations. The trial encompassed one fermentation method used, and one cultivar tested, and therefore, outcomes may depend on the selected olive species used, processing regimen employed, and fermentation conditions. Water activity was also only measured in the initial brines. While this method permitted evaluation of the immediate impact of salt substitution on water availability, observations of water activity during fermentation may contribute additional knowledge about dynamic changes taking place in the fermentation process. Moreover, sensory evaluation was performed among faculty and students located in a single academic institution. While the panel supplied preliminary information on sensory acceptance, it may not fully capture the preferences of the wider consumer base. Hence, studies conducted on larger and more diverse consumer populations in the future are proposed. Future studies should also investigate mineral salt substitution combined with bitterness-masking strategies, starter cultures, or encapsulated salt systems to improve sensory quality. Long-term storage and industrial-scale trials would be useful to evaluate product stability and scalability. Finally, combining microstructural and metabolomic analyses may provide deeper insight into ion–matrix interactions and their effects on texture, phenolic retention, and overall product quality.

5. Conclusion

This study showed that sodium chloride can be partially replaced with mineral salts in table olives for the reduction of sodium in fermented table olives with its technological performance intact in this study. Fermentation succeeded with all the recipes according to proper acidification and water activity. Calcium chloride maintained structural integrity of the tissues, which would limit textural degradation during fermentation considerably, while potassium chloride reduces the sodium concentration but increases bitterness. Fermentation time was the main contributor to the loss of bioactive compounds, but the mixed-salt system resulted in increased phenolic retention at the later stages. Mineral properties confirmed the high rate of the exchange with ions which decreased sodium, increased potassium, and calcium. The perception analysis showed that a NaCl/KCl/CaCl₂ formulation would ensure the optimal balance of the solution, minimizing bitterness and maintaining acceptable texture and saltiness. The industrial application of mixed mineral salt brines constitutes an economically viable and scalable route to achieve sodium-reducing low-sodium fermented olives and, at the same time, maintain technological quality and consumer acceptability.

Data Availability Statement

The data that supports the findings of this study are available from the corresponding author upon reasonable request.

References

• AHMAD, M.N., MEHYAR, G.F. and OTHMAN, G.A., 2021. Nutritional, functional and microbiological characteristics of Jordanian fermented green Nabali Baladi olives. Grasas y Aceites, vol. 72, no. 1, pp. e396. https://doi.org/10.3989/gya.1258192
  » https://doi.org/10.3989/gya.1258192
• AL-ISMAIL, K.M., AHMAD, R., AL-DABBAS, M., AJO, R.Y. and RABABAH, T., 2011. Some physiochemical properties of olive and olive oil of three Jordanian olive varieties. La Rivista Italiana delle Sostanze Grasse, vol. 88, no. 3, pp. 191-198.
• AMBRA, R., LUCCHETTI, S., MONETA, E., PEPARAIO, M., NARDO, N., BAIAMONTE, I., DI COSTANZO, M.G., SAGGIA CIVITELLI, E. and PASTORE, G., 2017. Effect of partial substitution of sodium with potassium chloride in the fermenting brine on organoleptic characteristics and bioactive molecules occurrence in table olives debittered using Spanish and Castelvetrano methods. International Journal of Food Science & Technology, vol. 52, no. 3, pp. 662-670. https://doi.org/10.1111/ijfs.13319
  » https://doi.org/10.1111/ijfs.13319
• ARTAJO, L.S., ROMERO, M.P. and MOTILVA, M.J., 2006. Transfer of phenolic compounds during olive oil extraction in relation to ripening stage of the fruit. Journal of the Science of Food and Agriculture, vol. 86, no. 4, pp. 518-527. https://doi.org/10.1002/jsfa.2384
  » https://doi.org/10.1002/jsfa.2384
• ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS – AOAC, 2002. Official method 991.25: calcium, magnesium, and phosphorus in cheese—atomic absorption spectrophotometric and colorimetric method‏ Arlington: AOAC.
• BAUTISTA-GALLEGO, J., ARROYO-LÓPEZ, F.N., DURÁN-QUINTANA, M.C. and GARRIDO-FERNÁNDEZ, A., 2010. Fermentation profiles of Manzanilla-Aloreña cracked green table olives in different chloride salt mixtures. Food Microbiology, vol. 27, no. 3, pp. 403-412. https://doi.org/10.1016/j.fm.2009.11.015 PMid:20227606.
  » https://doi.org/10.1016/j.fm.2009.11.015
• BAUTISTA-GALLEGO, J., ARROYO-LÓPEZ, F.N., ROMERO-GIL, V., RODRÍGUEZ-GÓMEZ, F., GARCÍA-GARCÍA, P. and GARRIDO-FERNÁNDEZ, A., 2015. Fermentation profile of green Spanish-style Manzanilla olives according to NaCl content in brine. Food Microbiology, vol. 49, pp. 56-64. https://doi.org/10.1016/j.fm.2015.01.012 PMid:25846915.
  » https://doi.org/10.1016/j.fm.2015.01.012
• BLEVE, G., TUFARIELLO, M., DURANTE, M., PERBELLINI, E., RAMIRES, F.A., GRIECO, F., CAPPELLO, M.S., DE DOMENICO, S., MITA, G., TASIOULA-MARGARI, M. and LOGRIECO, A.F., 2014. Physico-chemical and microbiological characterization of spontaneous fermentation of Cellina di Nardò and Leccino table olives. Frontiers in Microbiology, vol. 5, pp. 570. https://doi.org/10.3389/fmicb.2014.00570 PMid:25389422.
  » https://doi.org/10.3389/fmicb.2014.00570
• CHATA, Y.Y., MAMANI, A.G., GALLEGOS-ARATA, M. and CARTAGENA-CUTIPA, R., 2024. Effects of sodium substitution with potassium in brines for packing natural black olives of the criolla cultivar. Grasas y Aceites, vol. 75, no. 4, pp. 2251. https://doi.org/10.3989/gya.1200232.2251
  » https://doi.org/10.3989/gya.1200232.2251
• DALLOUL, L. and ERTEN, H. 2018. Determination of physicochemcical properties of Cracked Green cv. Sari Ulak olives fermented by different chloride salts. Ç. Ü Fen ve Mühendislik Bilimleri Dergisi Yil, vol. 35, no. 9, pp. 11-21.
• ERDOGAN, M., AGIRMAN, B.İ.L.A.L., BOYACI-GUNDUZ, C.P. and ERTEN, H.Ü.S.E.Y.İ.N., 2018. Partial replacement of sodium chloride with other chloride salts for the production of black table olives from cv. Gemlik. Quality Assurance and Safety of Crops & Foods, vol. 10, no. 4, pp. 399-410. https://doi.org/10.3920/QAS2018.1314
  » https://doi.org/10.3920/QAS2018.1314
• EUROPEAN UNION, 2011 [viewed 12 March 2026]. Regulation (EU) No 1169/2011 of the European Parliamentand of the Council of 25 October 2011 on the Provision of Food Information to Consumers.Official Journal of the European Union[online], vol. 304, pp. 18-63. Available from:https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=celex%3A32011R1169
  » https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=celex%3A32011R1169
• FERNÁNDEZ, A.G., ADAMS, M.R. and FERNANDEZ-DIEZ, M.J., 1997.Table olives: production and processing Berlin: Springer Science & Business Media‏. https://doi.org/10.1007/978-1-4899-4683-6
  » https://doi.org/10.1007/978-1-4899-4683-6
• GHANBARI, R., ANWAR, F., ALKHARFY, K.M., GILANI, A.H. and SAARI, N., 2012. Valuable nutrients and functional bioactives in different parts of olive (Olea europaea L.) a review. International Journal of Molecular Sciences, vol. 13, no. 3, pp. 3291-3340. https://doi.org/10.3390/ijms13033291 PMid:22489153.
  » https://doi.org/10.3390/ijms13033291
• HUMEID, M.A., TAKRURI, H.R. and DAQQAQ, R.F., 1991. Nabali olive oil ripening and oil properties. Nutrition and Health, vol. 7, no. 3, pp. 151-154. https://doi.org/10.1177/026010609100700304 PMid:1923072.
  » https://doi.org/10.1177/026010609100700304
• INTERNATIONAL OLIVE COUNCIL – IOC, 2004. Trade standards applying to table olives‏ Madrid: IOC.
• INTERNATIONAL OLIVE COUNCIL – IOC, 2022 [viewed 10 February 2026]. Estadísticas mundiales sobre aceite de oliva y aceitunas de mesa [online]. Madrid: IOC. Available from: https://www.internationaloliveoil.org/que-hacemos/unidad-de-asuntos-econonicos-y-promocion/? lang=es#figures
  » https://www.internationaloliveoil.org/que-hacemos/unidad-de-asuntos-econonicos-y-promocion/?
• INTERNATIONAL ORGANIZATION FOR STANDARDIZATION – ISO, 2010. ISO 13229: sensory analysis: methodology: general guidance for establishing a sensory profile (Report) Geneva: ISO.
• JORDAN. Ministry of Agriculture – MOA, 2016. Agricultural statistical yearbook Amman: MOA.
• KANAVOURAS, A., GAZOULI, M., LEONIDAS, L.T. and PETRAKIS, C., 2005. Evaluation of Greek-style black table olives in salt varying brines. Grasas y Aceites, vol. 56, no. 2, pp. 106-115. https://doi.org/10.3989/gya.2005.v56.i2.117
  » https://doi.org/10.3989/gya.2005.v56.i2.117
• KAVDIR, I., BUYUKCAN, M.B., KOCABIYIK, H.A.B.İ.B., SEKER, M. and LU, R., 2009. Nondestructive olive quality detection using FT-NIR spectroscopy in reflectance mode. Acta Horticulturae, no. 824, pp. 373-380. https://doi.org/10.17660/ActaHortic.2009.824.44
  » https://doi.org/10.17660/ActaHortic.2009.824.44
• LANZA, B., DI SERIO, M.G., IANNUCCI, E., RUSSI, F. and MARFISI, P., 2010. Nutritional, textural and sensorial characterisation of Italian table olives (Olea europaea L. cv. ‘Intosso d’Abruzzo’). International Journal of Food Science & Technology, vol. 45, no. 1, pp. 67-74. https://doi.org/10.1111/j.1365-2621.2009.02104.x
  » https://doi.org/10.1111/j.1365-2621.2009.02104.x
• LOPEZ, A., GARCÍA, P. and GARRIDO, A., 2008. Multivariate characterization of table olives according to their mineral nutrient composition. Food Chemistry, vol. 106, no. 1, pp. 369-378. https://doi.org/10.1016/j.foodchem.2007.05.055
  » https://doi.org/10.1016/j.foodchem.2007.05.055
• LOPEZ-LOPEZ, A., BAUTISTA-GALLEGO, J., MORENO-BAQUERO, J.M. and GARRIDO-FERNANDEZ, A., 2016. Fermentation in nutrient salt mixtures affects green Spanish-style Manzanilla table olive characteristics. Food Chemistry, vol. 211, pp. 415-422. https://doi.org/10.1016/j.foodchem.2016.05.093 PMid:27283650.
  » https://doi.org/10.1016/j.foodchem.2016.05.093
• LÓPEZ-LÓPEZ, A., MORENO-BAQUERO, J.M. and GARRIDO-FERNÁNDEZ, A., 2023. Relationships between Na, K, and Ca mineral nutrients in brine and table olive flesh. Nutritional labelling implications. Lebensmittel-Wissenschaft + Technologie, vol. 189, pp. 115546. https://doi.org/10.1016/j.lwt.2023.115546
  » https://doi.org/10.1016/j.lwt.2023.115546
• MIRALIAKBARI, H. and SHAHIDI, F., 2008. Lipid class compositions, tocopherols and sterols of tree nut oils extracted with different solvents. Journal of Food Lipids, vol. 15, no. 1, pp. 81-96. https://doi.org/10.1111/j.1745-4522.2007.00104.x
  » https://doi.org/10.1111/j.1745-4522.2007.00104.x
• OTHMAN, G.A., MAHMOUD, I.F., AL-BASHABSHEH, Z.Q., ALOMARI, D.A., KARASNEH, H.D. and ALI, L.N., 2026. Partial NaCl replacement with KCl enhances microbial dynamics and antioxidant potential in fermented nabali baladi olives. Applied Food Research, vol. 6, no. 1, pp. 101831. https://doi.org/10.1016/j.afres.2026.101831
  » https://doi.org/10.1016/j.afres.2026.101831
• ÖZAY, G. and BORCAKH, M., 1995. Effect of brine replacement and salt concentration on the fermentation of naturally black olives. Food Research International, vol. 28, no. 6, pp. 553-559. https://doi.org/10.1016/0963-9969(95)00054-2
  » https://doi.org/10.1016/0963-9969(95)00054-2
• PANAGOU, E.Z., HONDRODIMOU, O., MALLOUCHOS, A. and NYCHAS, G.J., 2011. A study on the implications of NaCl reduction in the fermentation profile of Conservolea natural black olives. Food Microbiology, vol. 28, no. 7, pp. 1301-1307. https://doi.org/10.1016/j.fm.2011.05.008 PMid:21839379.
  » https://doi.org/10.1016/j.fm.2011.05.008
• PANAGOU, E.Z., SCHILLINGER, U., FRANZ, C.M. and NYCHAS, G.J.E., 2008. Microbiological and biochemical profile of cv. Conservolea naturally black olives during controlled fermentation with selected strains of lactic acid bacteria. Food Microbiology, vol. 25, no. 2, pp. 348-358. https://doi.org/10.1016/j.fm.2007.10.005 PMid:18206777.
  » https://doi.org/10.1016/j.fm.2007.10.005
• PIRES-CABRAL, P., BARROS, T., MATEUS, T., PRATA, J. and QUINTAS, C., 2018. The effect of seasoning with herbs on the nutritional, safety and sensory properties of reduced-sodium fermented Cobrançosa cv. table olives. AIMS Agric. Food, vol. 3, no. 4, pp. 521-534. https://doi.org/10.3934/agrfood.2018.4.521
  » https://doi.org/10.3934/agrfood.2018.4.521
• RODRÍGUEZ-GÓMEZ, F., ROMERO-GIL, V., BAUTISTA-GALLEGO, J., GARCÍA-GARCÍA, P., GARRIDO-FERNÁNDEZ, A. and ARROYO-LÓPEZ, F.N., 2014. Production of potential probiotic Spanish-style green table olives at pilot plant scale using multifunctional starters. Food Microbiology, vol. 44, pp. 278-287. https://doi.org/10.1016/j.fm.2014.03.023 PMid:25084674.
  » https://doi.org/10.1016/j.fm.2014.03.023
• ROMEO, F.V., DE LUCA, S., PISCOPO, A., PERRI, E. and POIANA, M., 2009. Effects of post-fermentation processing on the stabilisation of naturally fermented green table olives (cv Nocellara etnea). Food Chemistry, vol. 116, no. 4, pp. 873-878. https://doi.org/10.1016/j.foodchem.2009.03.037
  » https://doi.org/10.1016/j.foodchem.2009.03.037
• SILVEIRA, A.C., AGUAYO, E., CHISARI, M. and ARTÉS, F., 2011. Calcium salts and heat treatment for quality retention of fresh-cut ‘Galia’melon. Postharvest Biology and Technology, vol. 62, no. 1, pp. 77-84. https://doi.org/10.1016/j.postharvbio.2011.04.009
  » https://doi.org/10.1016/j.postharvbio.2011.04.009
• SINOPOLI, D.A. and LAWLESS, H.T., 2012. Taste properties of potassium chloride alone and in mixtures with sodium chloride using a check‐all‐that‐apply method. Journal of Food Science, vol. 77, no. 9, pp. S319-S322. https://doi.org/10.1111/j.1750-3841.2012.02862.x PMid:22901084.
  » https://doi.org/10.1111/j.1750-3841.2012.02862.x
• TASSOU, C.C., KATSABOXAKIS, C.Z., GEORGET, D.M., PARKER, M.L., WALDRON, K.W., SMITH, A.C. and PANAGOU, E.Z., 2007. Effect of calcium chloride on mechanical properties and microbiological characteristics of cv. Conservolea naturally black olives fermented at different sodium chloride levels. Journal of the Science of Food and Agriculture, vol. 87, no. 6, pp. 1123-1131. https://doi.org/10.1002/jsfa.2823
  » https://doi.org/10.1002/jsfa.2823
• TASSOU, C.C., PANAGOU, E.Z. and KATSABOXAKIS, K.Z., 2002. Microbiological and physicochemical changes of naturally black olives fermented at different temperatures and NaCl levels in the brines. Food Microbiology, vol. 19, no. 6, pp. 605-615. https://doi.org/10.1006/fmic.2002.0480
  » https://doi.org/10.1006/fmic.2002.0480
• U.S. DEPARTMENT OF AGRICULTURE – USDA, 2020 [viewed 19 January 2026].Dietary guidelines for Americans, 2020-2025 [online]. 9th ed. Washington, D.C.: U.S. Department of Health and Human Services. Available from:https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf
  » https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf
• WANG, Y.J., YEH, T.L., SHIH, M.C., TU, Y.K. and CHIEN, K.L., 2020. Dietary sodium intake and risk of cardiovascular disease: a systematic review and dose-response meta-analysis. Nutrients, vol. 12, no. 10, pp. 2934. https://doi.org/10.3390/nu12102934 PMid:32992705.
  » https://doi.org/10.3390/nu12102934

Edited by

• Editor:
  Takako Matsumura Tundisi

Publication Dates

• Publication in this collection
  27 July 2026
• Date of issue
  2026

History

• Received
  07 Apr 2026
• Accepted
  05 June 2026