Fermentation Brines Research Articles

Metagenomics reveals microbial communities and functional differences during chili pepper (Capsicum frutescens L.) natural fermentation: Effects of brines and containers

AbstractThe study aimed to investigate the effect of fermentation brines and containers on the composition and functional dissimilarity of microbiota in fermented chili peppers: pool with fresh brine (PFB), pool with aged brine (PAB), jar with FB, and jar with AB. The results showed that brines had a greater impact on microbial diversity and fungal community structure than containers, whereas containers had a greater impact on bacterial community structure than brines. At the end of chili pepper fermentation, the dominant bacteria were unclassified_g__Pseudomonas, Lactobacillus_alimentarius, and Halococcus_thailandensis, whereas the dominant fungi were Pichia_membranifaciens and Wallemia_ichthyophaga. Based on the metagenomics functional analysis, the dominant bacteria and fungi were highly related to amino acid metabolism, glycerophospholipid metabolism, and most enzymes that promote carbohydrate substrate modulation. The fermented brines had a larger impact than containers on microbial function. Specifically, the use of FB was found to be beneficial for the biosynthesis of tetracycline, carotenoid, and isoflavonoid. On the other hand, AB was found to be beneficial for the biosynthesis of unsaturated fatty acids, amino acids, and various types of N‐glycan.

Effect of Growing Regions on Discrimination of Turkish-Style Black Table Olives from Gemlik Cultivar.

Gemlik is a cultivar that grows in a distinct region of Turkiye and is ideal for brine fermentation of brine black table olives. Bursa Protected Designated Origin (PDO) and Izmir non-PDO Gemlik table olives have high levels of oleic acid (74%), total phenol (190 mg/kg), and dry matter (57%), while being low in linoleic acid (8%). The pH values and salt contents were observed to be in the range of 4.1 to 4.3 and 3.9% to 4.8%, respectively. During the fermentation of Gemlik table olives, a mass transfer occurred, resulting in a reduction in reducing sugar and total sugar contents as well as an increase in the salt content of the olives. Despite the reduction of phenolic content in both Gemlik PDO and non-PDO table olives, their antioxidant capacity remains high after fermentation. The oil content, antioxidant activity, phenolic contents, palmitic, palmitoleic, oleic, and linoleic acids were all found to be significant variables in distinguishing between Gemlik PDO and non-PDO table olives using PLS-DA analysis. There is a statistically significant correlation between the phenolic content and oleic (0.588) and linoleic (-0.659) acids (p < 0.05). Bursa PDO and Izmir non-PDO exhibit enhanced nutritional quality and antioxidant activity, unequivocally differentiating them from Hatay and Mersin non-PDO Gemlik table olives with 98% accuracy through discriminant analysis (p < 0.05). PLS-DA and DA can effectively identify variations in the quality of Turkish-style black table olives preserved in brine, originating from PDO and non-PDO growing areas.

Understanding the transcriptomic response of Lactiplantibacillus pentosus LPG1 during Spanish-style green table olive fermentations.

Lactiplantibacillus pentosus (Lbp. pentosus) is a species of lactic acid bacteria with a great relevance during the table olive fermentation process, with ability to form non-pathogenic biofilms on olive epidermis. The objective of this work is to deepen into the genetic mechanisms of adaptation of Lpb. pentosus LPG1 during Spanish-style green table olive fermentations, as well as to obtain a better understanding of the mechanisms of adherence of this species to the fruit surface. For this purpose, we have carried out a transcriptomic analysis of the differential gene expression of this bacterium during 60 days of fermentation in both brine and biofilms ecosystems. In brines, it was noticed that a total of 235 genes from Lpb. pentosus LPG1 were differentially expressed during course of fermentation and grouped into 9 clusters according to time-course analysis. Transport and metabolism of carbohydrates and amino acids, energy production, lactic acid and exopolysaccharide synthesis genes increased their expression in the planktonic cells during course of fermentation. On the other hand, expression of genes associated to stress response, bacteriocin synthesis and membrane protein decreased. A total of 127 genes showed significant differential expression between Lpb. pentosus LPG1 planktonic (brine) and sessile (biofilms) cells at the end of fermentation process (60 days). Among the 64 upregulated genes in biofilms, we found genes involved in adhesion (strA), exopolysaccharide production (ywqD, ywqE, and wbnH), cell shape and elongation (MreB), and well as prophage excision. Deeping into the genetic bases of beneficial biofilm formation by Lpb. pentosus strains with probiotic potential will help to turn this fermented vegetable into a carrier of beneficial microorganisms to the final consumers.

Effect of brine fermentation on nitrogen metabolism and microbial community of Allium chinense bulbs and identification of lactic acid bacteria with nitrite degradation function

The effects of brine addition on the dynamic changes in nitrogen transformation, and bacterial community of fermented Allium chinense (A. chinense) bulbs, as well as screening and identification of lactic acid bacteria (LAB) with nitrite degradation function were explored in this work. In contrast with natural fermentation (NC) group, supplementation with aged pickle brine (PBa) declined the pH value. In terms of nitrogen metabolism, PBa fermentation could enhance the degradation of nitrite via activating nitrite reductase (NIR). Besides, the ammonium contents showed a small fluctuation without significant difference during fermentation. Furthermore, PBa could alter the microbial diversity of A. chinense bulbs to modulate nitrogen metabolism-related genes including nirA/B/D and narK/G/H. Correlation analysis confirmed that the LAB abundances exhibited significant negative relationships with the levels of nitrite. These results inferred that the microbial pathways of nitrite degradation in A. chinense bulbs might be attributed to denitrification. Accordingly, the present findings suggested that brine fermentation could promote the nitrogen metabolism in A. chinense bulbs via regulating the microbial community and expression of denitrification-related genes, thus shortening the fermentation time compared to the NC group. Moreover, one strain of LAB (L7) was isolated from PBa group by pure culture method, which showed high similarity to Lactiplantibacillus argentoratensis HBUAS570840, and strong nitrite-lowering ability, high salt tolerance, and strong antibacterial activity. Therefore, the addition of brine can be utilized as an effective strategy to modulate the nitrogen metabolism of A. chinense bulbs.

Concentration of phenolic compounds from olive washing wastewater by forward osmosis using table olive fermentation brine as draw solution

The olive industry has a considerable amount of process water consumption. As a result of the process, a large volume of oil mill wastewater (OMW) and table olive wastewater (TOW), both of them with high concentrations of organic matter, phenolic compounds and conductivity, are released. The appropriate management of these wastewaters is of paramount importance due to their toxic impacts on the environment. In this work, forward osmosis (FO) process is presented as an option to concentrate phenolic compounds for their further recovery. Two membranes, OsmoF2OTM (FTS, USA) and HFFO.6 (Aquaporin, Denmark) were evaluated with NaCl as draw solution (DS) and olive oil washing wastewater (OOWW) filtered at 5μm (5F) as feed solution (FS). Both membranes were able to concentrate the phenolic compounds with acceptable volume reduction (VR) values. The HFFO.6 membrane, which presented the lowest passage of phenolic compounds (TPhC) to the DS, was tested with fermentation brine from table olive processing (FTOP) as DS. As FS the same 5F-OOWW as well as an OOWW ultrafiltration permeate (UF-OOWW) were considered. Interestingly, greater percentages of TPhC concentration were observed compared to the tests with NaCl as DS (74.13–76.93% versus 62.6%, respectively). Although the tests with UF-OOWW presented greater flux, the recovery percentages of TPhC were similar, even slightly lower than those obtained with 5F-OOWW. Therefore, FO appears as a promising option to concentrate TPhC from OOWW and as well as to dilute FTOP. Thus both wastewaters from the olive industry could be treated at the same time.

Consumer perception and physicochemical characterization of a new product made from lactic acid fermented orange peels

A new product made from orange peels discarded from juice making has been characterized during the present study. In order to reduce its bitterness, orange peel was fermented during 10 days in two different sugary brines (2% or 5% NaCl content) using a Lactiplantibacillus plantarum strain. The lactic acid fermentation process was characterized by determining pH, sucrose, and the organic acids content. The original peel and the final products were characterized by instrumental texture and color determination, and total flavonoids content. In addition, consumers' expectations and perception of the new products were also studied using an online survey and a consumer study in which acceptance and perceived bitterness were assessed. Results suggested that the 2% NaCl-fermentation process allowed a greater bacteria development (with a higher lactic acid production and larger differences in color parameters with the original peel than the 5% NaCl-fermented samples) although both fermented samples were significantly different from the original peel in their physicochemical characteristics. Total flavonoids content, which has been related to bitterness perception, was significatively lower in the fermented samples than in the raw orange peel (50% reduction). Spanish consumers’ expectations and perception of the new product were similar, and the snack made with the peel fermented in the 2% NaCl-brine was more liked than the same snack made with the original peel, or the 5% NaCl-fermented one. Using a lactic acid fermentation in a sugary brine was useful to decrease the bitterness perception and increase liking of the orange peel, meaning a potential valorization for this orange juice by-product.Implications for gastronomy.The present study includes the physico-chemical characterization and consumers’ perception of a new product developed with one of the main citrus by-products: orange peels. A new ingredient for the Spanish gastronomy is proposed, showing a potential use for one of the main HORECA (HOtels REstaurants Catering sector) and juices industry by-products. A simple lactic-acid fermentation process, inspired in the North-African gastronomy culture, is described, and the consumer perception of the new product, presented as a freeze-dried snack is shown, proposing a new way of decreasing this food waste in Spain. In addition, some ideas about how to decrease bitterness perception on flavonoids-rich materials are shown, contributing to the knowledge on other new foods development.

Conservação láctica de tomate tipo cereja cultivado sob irrigação com águas salinas

ABSTRACT The objective of this study was to evaluate the chemical composition of cherry tomato fruits produced under irrigation with saline water and subjected to lactic preservation. The design used was completely randomized, in a 6 × 5 factorial scheme, referring to the preservation by lactic fermentation with six mixtures of salts (100 g L-1 NaCl, 100 g L-1 CaCl2, 100 g L-1 KCl, 50 g L-1 NaCl + 50 g L-1 CaCl2, 50 g L-1 CaCl2 + 50 g L-1 KCl, and 50 g L-1 NaCl + 50 g L-1 KCl) and five levels of electrical conductivity of water (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1), with three replicates. Lactic fermentation brines promoted higher titratable acidity and soluble solids of cherry tomato fruits under saline water irrigation. Irrigation using water with electrical conductivity of 2.3 dS m-1 promoted higher soluble solids/titratable acidity ratio in cherry tomato fruits preserved in the formulations with 50 g L-1 NaCl + 50 g L-1 KCl and 50 g L-1 CaCl2 + 50 g L-1 KCl. The highest moisture contents were found in fruits preserved with 100 g L-1 CaCl2 and 50 g L-1 NaCl + 50 g L-1 CaCl2. Brine formulations for lactic preservation containing 100 g L-1 NaCl and 100 g L-1 CaCl2 promoted higher contents of vitamin C and flavonoids in cherry tomato fruits, regardless of the salinity of irrigation water.

Buffer Models for pH and Acid Changes Occurring in Cucumber Juice Fermented with Lactiplantibacillus pentosus and Leuconostoc mesenteroides

The pH changes that occur during the fermentation of vegetables by lactic acid bacteria depend on the production of weak acids and on the buffering of the fermentation medium. Undefined buffering components of fermentation media make estimates of pH from acid production difficult. The objective of this research was to develop buffer models for a model cucumber fermentation brine system linking pH changes to acid concentrations. A novel titration method was used to measure buffer capacity in cucumber juice medium made from three grades of pickling cucumbers based on diameter. Fermentation of juice made from cucumbers of different sizes resulted in differences in fermentation biochemistry. The results of modeling indicated that the pH of the medium after 24 and 48 h of fermentation by heterolactic Leuconostoc mesenteroides and homolactic Lactiplantibacillus pentosus could be predicted from acid concentrations based on the measured buffer capacity of the corresponding unfermented medium. The differences for all observed and predicted pH values of the fermentation samples, based on measured acid concentrations, had a root mean square error of 0.064 pH units. The buffer models included a quantitative measure of the effect on pH of the malolactic reaction caused by the lactic acid bacteria. These models may have application for assessing the influence of a variety of lactic acid bacteria buffering reactions on pH and fermentation ecology by linking pH to fermentation acid concentrations.

Effects of microbial community structure and its co-occurrence on the dynamic changes of physicochemical properties and free amino acids in the Cantonese soy sauce fermentation process

The soy sauce produced by Cantonese fermentation has a unique flavor, among which brine fermentation plays an important role. In this fermentation process, 61 volatile compounds, including 19 esters, 10 aldehydes, 9 alcohols, 5 phenols, and 18 others, were identified by headspace solid-phase microextraction–gas chromatography–mass spectrometry. Seventeen kinds of free amino acids were detected by high-performance liquid chromatography. Results showed that Touyou, which comprised 1.5 g/100 g total nitrogen, 1.0 g/100 mL amino acid nitrogen, 3.66 g/100 g reducing sugar, 1.44 g/100 mL total acid, 17.04 g/100 mL salt content, and 27.3% umami free amino acids, had excellent quality. High-throughput sequencing was used to identify microorganisms. The top 3 of bacteria were Weissella, Staphylococcus, and Lactobacillus, and the top 3 fungi were Aspergillus, Zygosaccharomyces, and Candida. The co-occurrence network analysis of microorganisms showed that the top-ranked microorganisms were Plectosphaerella, Aureobasidium, unidentified_Mortierellales_sp, Glutinomyces, Faecalibacterium, and Cladophialophora. Then, eight microorganisms (VIP[pred] > 1) were obtained by two-way orthogonal partial least squares model, namely, Staphylococcus, Candida, Weissella, Aspergillus, Zygosaccharomyces, Lactobacillus, Monilinia, and Clavispora. Correlation analysis showed that these microorganisms were strongly related to flavor metabolites. This study explored the dynamics of traditional Cantonese fermentation, which has positive implications for optimizing this traditional fermentation process.

Quality changes in Indian mackerel ( Rastrelliger kanagurta ) during preservation with saturated brine fermentation technique

Indian mackerel, Rastrelliger kanagurta is one of the most preferred fatty fish; however, economical preservation of fatty fishes is least documented in India. Saturated brine (23%) fermentation of Indian mackerel was studied for 120 days. Increment of lipid (2.25%), reduction of protein (5%) and salt content of 14%–15% with pH of around 6.0 was observed. Hardness fluctuated initially but stabilized at maturation. Fermentation imparted pleasant aroma to the product with minimal fat oxidation. Total plate count ranged from 3.80 to 5.44 log cfu/g. Coliforms and Escherichia coli were <1.8 MPN/g in final product. The product was stable at ambient condition under 95% vacuum in retortable pouch throughout the storage period (30 days). Botulinum toxin was examined and found absent in the analyzed samples. Sensory score indicated high acceptance of the product. Thus, the study illustrated that saturated brine fermentation preserves fatty fish adequately, producing safe and healthy fermented fish product with enhanced shelflife. Practical applications Indian mackerel being a fatty fish is prone to quick oxidation and spoilage; hence, a cost-effective preservation technique is required. Saturated brine fermented Indian mackerel has benefits of enhanced taste and aroma with minimal oxidation of the product. This preservation technique induces the product to remain stable at ambient condition with added shelflife owing to reduced pH and water activity. The preservation process of saturated brine fermentation acts as a value addition to Indian mackerel as it develops the product with similar attributes of lona ilish, a popular salt-fermented fish product in North-East India. This product can be economically adopted by fisher folks, self-help groups, and several other communities. This product can help to improve food and nutritional security in rural areas.

Recent progress and advances in soy sauce production technologies: A review

Soy sauce is a traditional condiment that, because of its documented health benefits, is becoming increasingly ubiquitous. It is produced in a two-stage fermentation process consisting of a solid-state fermentation or koji involving mold, followed by brine fermentation or moromi involving halophilic bacteria and salt-tolerant yeasts. Efforts have been made to tackle the present limitations facing this industry, including the long fermentation time, the high salt concentrations, and the generated by-products with the use of genetic engineering such as genome shuffling, mutagenesis, enzyme alteration, mixed starter cultures, and gamma-aminobutyric acid-generating microorganisms. This analysis offers an overview of the latest technologies employed in the soy sauce industry, explaining the various conventional and alternative feedstocks used, the manufacturing processes, the microbial community, and their main role. The transition of soy sauce from a standard condiment to a potential functional food will also be explored. Novelty impact statement Soy sauce is a traditional food condiment that is currently transitioning into a functional food. With rapid advancements in food science, this review covers recent progress and advances in soy sauce production technologies. In addition, it also reviews strategies to resolve long fermentation time, high salt content, and utilization of soy sauce residues to value-added biodiesel.

Yeast dynamics in the black table olives processing using fermented brine as starter

Spontaneous fermentation with autochthonous yeasts is the most traditional method used for the production of black table olives, which requires minimal intervention. The aim of this study was to evaluate the effects of adding a brine starter, developed from one-year spontaneously fermented black table olives, on the microbiological, chemical, and sensory characteristics of naturally fermented Taggiasca table olives. The olives were fermented in brine containing 12% (w/v) NaCl with 0.6% (w/v) citric acid and inoculated with a selected brine starter containing primarily Pichia manshurica (87% predominance) and Saccharomyces cerevisiae (10% predominance). Brine and olives samples were analysed at the start of the experiment and after 3, 6, 9, and 12 months of fermentation. The P. manshurica and S. cerevisiae present in the brine starter drove the entire fermentation process, along with other autochthonous species that were not included in the starter, including Zygosaccharomyces mrakii. Spoilage microorganisms and undesired off-odours and off-flavours were not present at the end of fermentation. When compared to the control, the use of the brine starter increased the total yeast population in the brine during the first 6 months of fermentation, thus shortening the debittering time of the fruits and improving the taste complexity of the final product.

Proposal for technological adaptation of small-sized green olives to Spanish-STYLE processing

In this study, small-sized green olives were assessed for processing as Spanish-style table olives. Technological adaptations included the selection of three lye treatments, combined with a 3 h washing, a subsequent fermentation for 105 days in brine (12% NaCl (w/v) acidified with hydrochloric acid, 2.3 mL/L of brine) using a starter culture (OleicaStarter®) and preservation for 7 months in the fermentation brine fortified with NaCl up to 9%. Different physicochemical (pH, titratable, combined acidity, sodium chloride, sugars, fermentable matter, colour and firmness of fruits), and microbiological (yeasts, lactic acid bacteria and Enterobacteriaceae) and parameters were monitored during processing of the olives. The results showed that lye treatment with 3.4% sodium hydroxide was the most suitable treatment since it presented the highest values of titratable acidity. At the end of fermentation, all treatments presented physicochemical and microbiological parameters compatible with the production of Spanish-style table olives. Likewise, high levels of lactic acid bacteria present on the fruit epidermis could make these olives suitable as carriers of functional bacteria after ingestion (6.8–6.9 log CFU/g). Finally, preservation can maintain the stability and quality of table olives. All the results highlight that small-sized green olives can be successfully processed as Spanish-style table olives.

Assessing the Effect of Ozonated Water on Microbial Load and Quality of Nocellara Etnea Table Olives

ABSTRACT The effect of ozonated water on quality and peel microbial load reduction of Nocellara Etnea (NE) olives was evaluated. Different ozone concentrations in water and different time of contact were tested. Moreover, two different ozonated water washing methods, dipping, and continuous shower, were compared. Color, texture, chemical, and microbiological analyses were performed before and after treatments and after 20 days of fermentation in brine with and without Lactiplantibacillus plantarum starter culture at 108 CFU/mL. The continuous shower with 6.5 ppm ozonated water for 10 min led to a reduction of 1 logarithmic unit for mesophilic aerobic bacteria and 1.47 log unit for yeasts and mold population compared to water washing. Olive firmness and color were affected differently.

Correlation of the bacterial communities with umami components, and chemical characteristics in Zhejiang xuecai and fermented brine

Xuecai is a Chinese-fermented vegetable product that has attracted much attention because of its unique umami taste. However, investigations of the bacterial communities, umami components and chemical characteristics in xuecai and the brine have not yet been conducted. In this study, the bacterial communities and their correlations with the umami components and the chemical characteristics are investigated. The results showed that significantly higher contents of total protein, total acid, amino acid nitrogen, total sugar, titratable acidity, salt, amino acids and organic acids, as well as significantly lower nitrite concentrations were observed in the brine samples. The supervised pattern recognition method revealed that the xuecai and brine could be distinguished by these indicators. In addition, the xuecai and brine were both dominated by Lactobacillus, Halanaerobium and Halomonas. A correlation analysis showed that halophilic bacteria had a positive effect on the umami components and chemical characteristics of the xuecai and brine. However, lactic acid bacteria both showed a negative correlation with amino acids and most organic acids. Membrane transport, carbohydrate metabolism and amino acid metabolism were the most abundant pathways. These results enhance our understanding of the bacterial communities, as well as the umami components and chemical characteristics in Zhejiang xuecai and brine.

Formation of γ-aminobutyric acid (GABA) during the natural lactic acid fermentation of cucumber

This study investigated γ-aminobutyric acid (GABA) formation during natural lactic acid fermentation of cucumbers. Two lots of cucumbers were fermented or acidified in duplicate in 4 % sodium chloride (NaCl) brine and analyzed for GABA content over 6 months storage. GABA was present in fresh and acidified pickling cucumbers at 0.83 ± 0.16 mM and 0.56 ± 0.30 mM, respectively. Additional GABA was generated in fermented cucumbers (1.21 ± 0.35 mM) and remained stable over time and during further processing. Brine salt content (2 % - 6 %) affected GABA formation with greatest GABA formation in cucumber brined in 2 % NaCl (1.38 ± 0.31 mM). Commercially available, fermented cucumber pickles packed in their original fermentation brines contained more GABA (1.32 ± 0.25 mM) than acidified (0.46 ± 0.26 mM) or fermented, desalted and re-packed products (0.49 ± 0.32 mM). This work demonstrated that low-salt fermentation enhances GABA content in fermented cucumber products prepared for direct consumption.

Deciphering Microbial Community Dynamics and Biochemical Changes During Nyons Black Olive Natural Fermentations.

French PDO Nyons black table olives are produced according to a traditional slow spontaneous fermentation in brine. The manufacture and unique sensorial properties of these olives thus only rely on the autochthonous complex microbiota. This study aimed at unraveling the microbial communities and dynamics of Nyons olives during a 1.5-year-long spontaneous fermentation to determine the main microbial drivers and link microbial species to key metabolites. Fermentations were monitored at a local producer plant at regular time intervals for two harvests and two olive types (organically and conventionally grown) using culture-dependent and metabarcoding (ITS2 for fungi, V3-V4 region for bacteria) approaches. Olives and brines were also sampled for volatiles, organic acids and phenolic compounds. No major differences in microbiota composition were observed according to olive type or harvest period. Throughout the fermentation, yeasts were clearly the most dominant. ITS2 sequencing data revealed complex fungal diversity dominated by Citeromyces nyonsensis, Wickerhamomyces anomalus, Zygotorulaspora mrakii, Candida boidinii and Pichia membranifaciens species. Bacterial communities were dominated by the Celerinatantimonas genus, while lactic acid bacteria remained scarce. Clear shifts in microbial communities and biochemical profiles were observed during fermentation and, by correlating metabolites and microbiota changes, four different phases were distinguished. During the first 7 days, phase I, a fast decrease of filamentous fungal and bacterial populations was observed. Between days 21 and 120, phase II, W. anomalus and C. nyonsensis for fungi and Celerinatantimonas diazotrophica for bacteria dominated the fermentation and were linked to the pH decrease and citric acid production. Phase III, between 120 and 183 days, was characterized by an increase in acids and esters and correlated to increased abundances of Z. mrakii, P. membranifaciens and C. boidinii. During the last months of fermentation, phase IV, microbial communities were dominated by P. membranifaciens and C. boidinii. Both species were strongly correlated to an increase in fruity esters and alcohol abundances. Overall, this study provides an in-depth understanding about microbial species succession and how the microbiota shapes the final distinct olive characteristics. It also constitutes a first step to identify key drivers of this fermentation.

Integrated Membrane Process for the Treatment and Reuse of Residual Table Olive Fermentation Brine and Anaerobically Digested Sludge Centrate.

Management of wastewater is a major challenge nowadays, due to increasing water demand, growing population and more stringent regulations on water quality. Wastewaters from food conservation are especially difficult to treat, since they have high salinity and high organic matter concentration. The aim of this work is the treatment of the effluent from a table olive fermentation process (FTOP) with the aim of reusing it once the organic matter is separated. The process proposed in this work consists of the following membrane-based technologies: Ultrafiltration (UF) (UP005, Microdyn Nadir), Forward Osmosis (FO) (Osmen2521, Hydration Technology Innovation) and Nanofiltration (NF) (NF245, Dow). The FO process was implemented to reduce the salinity entering the NF process, using the FTOP as draw solution and, at the same time, to concentrate the centrate produced in the sludge treatment of a municipal wastewater treatment plant with the aim of obtaining a stream enriched in nutrients. The UF step achieved the elimination of 50% of the chemical oxygen demand of the FTOP. The UF permeate was pumped to the FO system reducing the volume of the anaerobically digested sludge centrate (ADSC) by a factor of 3 in 6.5 h. Finally, the ultrafiltrated FTOP diluted by FO was subjected to NF. The transmembrane pressure needed in the NF stage was 40% lower than that required if the ultrafiltration permeate was directly nanofiltered. By means of the integrated process, the concentration of organic matter and phenolic compounds in the FTOP decreased by 97%. Therefore, the proposed process was able to obtain a treated brine that could be reused in other processes and simultaneously to concentrate a stream, such as the ADSC.

Preservation by lactic fermentation and physicochemical characterization of okra produced underwater salinity and potassium fertilization

The use of saline water in agricultural production will be increasingly necessary in the next decades. However, postharvest quality may be compromised, as in okra, due to salt stress and/or factors inherent to storage and transportation. In this context, developing alternative methods of preservation, including lactic fermentation, may be a promising way to maintain and even improve the nutritional quality of okra. Thus, the objective was to evaluate the production components of okra subjected to different levels of water salinity and doses of potassium fertilization, and further to evaluate the preservation by lactic fermentation of okra fruits produced under water salinity. The first experiment was carried out in lysimeters under field conditions in Neossolo Regolítico (Psamment) of sandy loam texture in Pombal-PB, in a randomized block design in a 5 x 5 factorial scheme, testing 5 levels of irrigation water salinity (0.3; 1.3; 2.3; 3.3, and 4.3 dS m-1) and 5 doses of potassium fertilization (75; 112.5; 150; 187.5, and 225 mg of K2O kg-1 of soil), with three replicates. After that, the okra fruits produced under the different salinity levels were stored in six mixtures of salts present in lactic fermentation brine (100-0-0, 0-100-0, 0-0-100, 50-50-0, 0-50-50, and 50-0-50 of NaCl, CaCl2, and KCl, respectively), under a 5 x 6 factorial, with three replicates, in a completely randomized design. The post-harvest quality, after fermentation, was evaluated based on their physicochemical characteristics. Irrigation water salinity negatively affected the average length, average weight, titratable acidity, soluble solids/titratable acidity ratio, and pH of the okra fruits. Potassium doses increased the average diameter of okra fruits, minimizing the deleterious effects of irrigation water salinity. The vitamin C contents of pickled okra fruits were not compromised by salt stress. Among the lactic fermentation brines, the formulation containing the proportion NaCl:CaCl2 stands out as promoting the highest titratable acidity and soluble solids content in pickled okra fruits.

Mutagenic Analysis of Fermenting Strains and Fermented Brine for Stinky Tofu

Stinky tofu, a popular fermented food in Taiwan and South China, is conventionally made by open-type natural fermentation in which the product quality is not easily controlled. The Food Industry Research and Development Institute (FIRDI) in Taiwan has attempted to isolate the major fermenting strains from stinky brine in order to produce stinky tofu that is sanitary and ensure its quality. This study investigated the mutagenicities of isolated fermenting strains and their fermented brine for stinky tofu by two assays: (I) Ames test and (II) mutation assay with human lymphoblast TK6 cells. In the Ames test, the number of revertants of Salmonella typhimurium TA98 and TA100 was at the same levels under the dose of fermenting strain lysates (107 cfu/ plate) and 10-fold dilution of the fermented brine compared with the respective control. In the mutation assay with TK6 cells, the same samples were tested and the mutant frequencies were comparable to the respective control. Experimental results provided no evidence of mutagenic activity attributed to the tested materials.