Effects of Sodium Chloride Concentration on Firmness Retention of Cucumbers Fermented and Stored with Calcium Chloride

The firmness of cucumbers brined at 0.2% CaCl₂ was retained during fermentation (1 month) and storage (12 months) when 2.6, 4.2 or 5.8% NaCl also was present. Firmness retention was not improved (P≥0.05) during storage by increase in NaCl concentration to 11.9% after fermentation. In the absence of added NaCI, cucumbers were firm after fermentation, but firmness was reduced during storage to 69% of initial for whole cucumbers, 64% for mesocarp tissue, and 32% for endocarp tissue. Addition of uncharacterized softening enzymes. extracted from debris collected at a cucumber grading operation, resulted in softening of cucumbers brined at 1.8% NaCl in the absence of added CaC1₂. Addition of CaCl₂ reduced but did not eliminate softening by ths extract. Results indicated that the firmness of brined cucumbers could be retained at appreciably lower NaCl concentrations than those traditionally used but that the lower limit of NaCl required to prevent softening by possible contaminating enzymes is yet to be established.     

Fermentation of Cucumbers Brined with Calcium Chloride Instead of Sodium Chloride

ABSTRACT: Waste water containing high levels of NaCl from cucumber fermentation tank yards is a continuing problem for the pickled vegetable industry. A major reduction in waste salt could be achieved if NaCl were eliminated from the cucumber fermentation process. The objectives of this project were to ferment cucumbers in brine containing CaCl₂ as the only salt, to determine the course of fermentation metabolism in the absence of NaCl, and to compare firmness retention of cucumbers fermented in CaCl₂ brine during subsequent storage compared to cucumbers fermented in brines containing both NaCl and CaCl₂ at concentrations typically used in commercial fermentations. The major metabolite changes during fermentation without NaCl were conversion of sugars in the fresh cucumbers primarily to lactic acid which caused pH to decrease to less than 3.5. This is the same pattern that occurs when cucumbers are fermented with NaCl as the major brining salt. Lactic acid concentration and pH were stable during storage and there was no detectable production of propionic acid or butyric acid that would indicate growth of spoilage bacteria. Firmness retention in cucumbers fermented with 100 to 300 mM CaCl₂ during storage at a high temperature (45 °C) was not significantly different from that obtained in fermented cucumbers with 1.03 M NaCl and 40 mM CaCl₂. In closed jars, cucumber fermentations with and without NaCl in the fermentation brine were similar both in the chemical changes caused by the fermentative microorganisms and in the retention of firmness in the fermented cucumbers.     

Fermentation of Cucumbers Without Sodium Chloride

Cucumbers were successfully fermented and stored in the absence of sodium chloride (salt) under laboratory conditions, provided the fruit were blanched (3 min, 77°C) before brining in a calcium acetate buffer and the brine inoculated with Lactobacillus planturum. Bloater formation was prevented by blanching even when brines were not purged of CO₂. Firmness of cucumbers was similar in salt-free brines or those containing salt after 1 mo, but firmness of salt-free cucumbers was lower after storage for 12 mos. Under pilot-scale, commercial conditions, however, the cucumbers were severely bloated, and the firmness was unacceptable after storage for 7 mo, due apparently to Microbial recontamination after blanching.     

Influence of sodium chloride, pH, and lactic acid bacteria on anaerobic lactic acid utilization during fermented cucumber spoilage

Cucumbers are preserved commercially by natural fermentations in 5% to 8% sodium chloride (NaCl) brines. Occasionally, fermented cucumbers spoil after the primary fermentation is complete. This spoilage has been characterized by decreases in lactic acid and a rise in brine pH caused by microbial instability. Objectives of this study were to determine the combined effects of NaCl and pH on fermented cucumber spoilage and to determine the ability of lactic acid bacteria (LAB) spoilage isolates to initiate lactic acid degradation in fermented cucumbers. Cucumbers fermented with 0%, 2%, 4%, and 6% NaCl were blended into slurries (FCS) and adjusted to pH 3.2, 3.8, 4.3, and 5.0 prior to centrifugation, sterile-filtration, and inoculation with spoilage organisms. Organic acids and pH were measured initially and after 3 wk, 2, 6, 12, and 18 mo anaerobic incubation at 25 °C. Anaerobic lactic acid degradation occurred in FCS at pH 3.8, 4.3, and 5.0 regardless of NaCl concentration. At pH 3.2, reduced NaCl concentrations resulted in increased susceptibility to spoilage, indicating that the pH limit for lactic acid utilization in reduced NaCl fermented cucumbers is 3.2 or lower. Over 18 mo incubation, only cucumbers fermented with 6% NaCl to pH 3.2 prevented anaerobic lactic acid degradation by spoilage bacteria. Among several LAB species isolated from fermented cucumber spoilage, Lactobacillus buchneri was unique in its ability to metabolize lactic acid in FCS with concurrent increases in acetic acid and 1,2-propanediol. Therefore, L. buchneri may be one of multiple organisms that contribute to development of fermented cucumber spoilage. PRACTICAL APPLICATION: Microbial spoilage of fermented cucumbers during bulk storage causes economic losses for producers. Current knowledge is insufficient to predict or control these losses. This study demonstrated that in the absence of oxygen, cucumbers fermented with 6% sodium chloride to pH 3.2 were not subject to spoilage. However, lactic acid was degraded by spoilage microorganisms in reduced salt, even with pH as low as 3.2. Efforts to reduce salt in commercial brining operations will need to include control measures for this increased susceptibility to spoilage. Lactobacillus buchneri was identified as a potential causative agent and could be used as a target in development of such control measures.     

Solubilization of Cell Wall Bound, Thermostable Pectinesterase from Valencia Orange

Complete solubilization of citrus pectinesterase is not effected by alkaline salt buffers but is partially enhanced after degradation of the cell wall by pectinase and cellulase. After heating at 70°C for 2 min, the pectinesterase fractions solubilized after enzymatic cell wall degradation possessed three times the residual activity of the pectinesterase fractions solubilized by alkaline salt buffer. Isoelectric focusing prints of pectinesterase activity and SDS polyacrylamide gel electrophoresis suggest increased solubilization of a heat stable pectinesterase isozyme after cell wall degradation.     

Enzyme activities in cocoa beans during fermentation

The activities of endoprotease, aminopeptidase, carboxypeptidase, invertase (cotyledon and pulp), polyphenol oxidase and glycosidases were studied during heap fermentation of ICS-95 cocoa beans. These enzymes are of key importance in flavour precursor formation and in pigment degradation during cocoa fermentation. Optimal extraction and assay conditions were established to characterise the enzymes reactions and to quantify and compare enzyme activities during cocoa fermentation. The enzymes exhibited large differences in pH optima and stability during fermentation. Aminopeptidase, invertase (cotyledon and pulp) and polyphenol oxidase were strongly inactivated, carboxypeptidase was partly inactivated, whereas endoprotease and glycosidases remained active throughout the fermentation. Since many enzymes are inactivated during fermentation, it is generally recognised that the actual period of enzyme action is short. Although our results confirmed total inactivation for some enzymes, we show that several key enzymes are not completely inactivated during fermentation. Therefore, some enzyme reactions can continue throughout the whole fermentation process. Only polyphenol oxidase was strongly inactivated during sun and artificial drying of the beans. The other enzymes were stable during the drying process. Enzymes like endoprotease and glycosidases are still active in properly fermented and dried beans. © 1998 SCI.     

Fermentation of Cucumbers in Anaerobic Tanks

A procedure was developed and tested for fermentation of cucumbers at low concentrations of NaCl in experimental, anaerobic tanks. The procedure included washing of the cucumbers, use of a buffered cover brine composed of 0.045M calcium acetate, sodium chloride to equilibrate at 2.7% or 4.6%, Lactobacillus plantarum culture, and N₂ purging to remove dissolved CO₂. The fermentations were predominantly homofermentative, lactic acid accounting for 95% of the cucumber sugars fermented. Firmness retention of the fermented cucumbers during storage for 1 year was improved by heating packaged products to 69°C before storage, but firmness retention was acceptable in un-heated products.     

发酵辣椒组织软化的抑制初探

本文对发酵辣椒组织软化的抑制作了探索性研究,钙盐可用于抑制组织软化,其作用呈双曲线规律,0.14%的Ca^2 可有效抑制发酵辣椒后熟后熟过程中组织的软化,发酵完成后加入高浓度的NaCl或少量的苯甲酸钠有利于发酵辣椒较长期保藏时组织软化的抑制。辣椒组织软化的抑制处理宜在发酵之前进行。     

Catalase, Lipoxygenase, and Peroxidase Activities in Cucumber Pickles as Affected by Fermentation, Processing, and Calcium Chloride

Catalase, lipoxygenase, and peroxidase activities were determined in tissues and brines of pickling cucumbers during fermentation, storage, and after processing. Lipoxygenase and catalase were inactivated within three days of exposure to fermentation brines. Peroxidase activity was relatively unaffected by the first three days of brining, but it declined during fermentation, storage, and after processing. CaCl₂ reduced the loss of peroxidase activity in tissue and brine during fermentation and storage. Alum in post-desalting brine reduced peroxidase activity in processed pickles although CaCl₂ ameliorated its efficacy. No activity of catalase, lipoxygenase or peroxidase was detected in cucumber juice extracts fermented by four different lactic acid bacteria.     

Softening Effects of Monovalent Cations in Acidified Cucumber Mesocarp Tissue

Due to the importance of salt as an ingredient in cucumber pickle products, the effect of salt concentration on first-order softening rates during acid storage was determined. Softening rates of unfermented tissue increased as the NaCl increased from 0 to 1.5M, whether or not the tissue was blanched. For unheated, fermented tissue, softening rates increased between 0 and 0.2M NaCl but did not increase above 0.2M NaCl. Changes in the degree of pectin methylation were not highly correlated with changes in softening rates. The ions Li⁺, K⁺, Rb⁺, and Cs⁺ had softening effects similar to Na⁺. An enthalpy of activation of 145 kJ/mole was determined for softening of blanched tissue stored in 1.5M NaCl. This is the first demonstration of a softening effect by monovalent cations in cucumber tissue.     

Microbiological Preservation of Cucumbers for Bulk Storage Using Acetic Acid and Food Preservatives

ABSTRACT:  Microbial growth did not occur when cucumbers were preserved without a thermal process by storage in solutions containing acetic acid, sodium benzoate, and calcium chloride to maintain tissue firmness. The concentrations of acetic acid and sodium benzoate required to ensure preservation were low enough so that stored cucumbers could be converted to the finished product without the need to wash out and discard excess acid or preservative. Since no thermal process was required, this method of preservation would be applicable for storing cucumbers in bulk containers. Acid tolerant pathogens died off in less than 24 h with the pH, acetic acid, and sodium benzoate concentrations required to assure the microbial stability of cucumbers stored at 30 °C. Potassium sorbate as a preservative in this application was not effective. Yeast growth was observed when sulfite was used as a preservative.     

不同低温逆境条件下黄瓜果实的热特性参数变化

探讨低温逆境条件下黄瓜贮藏过程中热特性参数变化规律,对在2、5、8、11 ℃低温条件下黄瓜果实的热特性随贮藏时间的变化进行研究。结果发现：黄瓜在2、5、8 ℃条件下均有冷害发生,而在11 ℃条件下并未出现冷害;随着贮藏时间的延长,黄瓜的质量损失率会渐渐上升,而比热容因失水而下降;黄瓜的热导率在冷害发生前后出现拐点。实验结果表明,果实热特性参数的变化与其生物组织冷害具有一定的相关性。     

Potential role of native pickling cucumber polygalacturonase in softening of fresh pack pickles

This study examined the potential involvement of polygalacturonase (PG) in commercial pickling cucumbers on gradual softening of refrigerated and pasteurized fresh pack pickle products that adversely affects their market-life. PG activity was detected in all sources of commercial pickling cucumbers and refrigerated pickle spears, and activity was detected in some sources of pasteurized spears. Polygalacturonic acid hydrolysis determined from changes in fluidity, reducing groups and oligogalacturonides indicated involvement of both exo- and endo-PG. Treatment of pasteurized pickle mesocarp tissues with concentrated extracts from pickling cucumbers resulted in rapid softening and alteration of pectic substances. D-values for thermal inactivation of pickling cucumber PG at 75, 80, 85, and 90 °C were 22.0, 19.5, 14.5, and 4.2 min, respectively, indicating that residual activity would be expected in commercially pasteurized pickle products. It is concluded that residual cucumber PG could be responsible for softening of processed pickle products, and it is suspected that variations in textural quality of given products are caused by differences in residual types and levels of native PG. PRACTICAL APPLICATION: Since enzyme extracts from commercial pickling cucumbers were demonstrated to be capable of softening pickle tissues and that PG activity was present in some processed fresh pack products, methods that inactivate or eliminate the enzyme(s) should reduce softening of products during storage and marketing.     

Assuring Microbial and Textural Stability of Fermented Cucumbers by pH Adjustment and Sodium Benzoate Addition

Acidification of fermented cucumbers with HCl prevented utilization of lactic acid and resultant rise in brine pH (accompanied by formation of butyric, propionic and acetic acids, and n-propanol by spoilage bacteria) when they were stored at 0 or 4.4% NaCl. Firmness retention of the fermented cucumbers was reduced, however, if the brine pH were less than optimum pH 3.5, which assured microbial stability and acceptable firmness retention with 4.4% NaCl. At 0% salt, pH 3.0 insured microbial stability, but resulted in unacceptable firmness. Addition of 0.1% Na benzoate reduced the need to lower pH to assure microbial stability. Results indicated that pH control could be used to reduce the need for salt to insure stability of fermented cucumbers.     

Characteristics of Fish Sauce Made from Pacific Whiting and Surimi By-products During Fermentation Stage

ABSTRACT: The fermentation condition for producing Pacific whiting fish sauce was static atmospheric fermentation with 25% salt at 50 °C. The effective enzymes in fermentation were heat stable and salt tolerant. Fermentation at 50 °C gave higher yields than at 35 °C. Total nitrogen content of whole fish fermented at 50 °C reached the equivalent level of commercial fish sauce before 15 d, supporting the strong degradation effects of Pacific whiting enzymes at earlier stages. Soluble solid and relative gravity also reached commercial level at 60 d. However, color value of unripened fish sauce was far from commercial fish sauce, indicating that ripening may be necessary to develop proper color. Staphylococcus, Bacillus , and Micrococcus were found as predominant microorganisms during fermentation.     

Factors Influencing Softening of Salt-Stock Pickles in Air-Purged Fermentations

Cucumber fermentations in 1-gal glass jars were purged with air at high rates to study factors influencing softening of the cucumbers and treatments whit h might prevent softening. The cucumbers were softened much mere rapidly and extensively in fermentations purged at 100 ml air/min than at 20 ml air/min. This could not be prevented by initial acidification (up to 0.6% acetic acid) nor by brining at high brim: strength (up to 35° salometer). No soft pickles were found in air-purged lots treated in any of the following ways: (a) acidified and treated with hypochlorite and then buffered and inoculated with Lactobacillus plantarum (controlled fermentation process); (b) added 1.035% potassium sorbate;(c) used nitrogen for purging for first two days and then air-purged; and (d) the cucumbers were blanched and inoculated by washing unblanched cucumbers with the brine used to cover them. Pectinolytic enzyme assays were run on most fermentation brines, but enzyme activities were not well correlated with the extent of softening. The results indicate that softening of air-purged cucumbers is caused by the growth of some oxygen-dependent, sorbic acid-sensitive microorganism(s) growing in or on the cucumbers. The first day or two after brining appears to be the most critical in the development of the causative, organism(s).     

Cell Wall Monosaccharide Changes During Softening of Brined Cucumber Mesocarp Tissue

Blanched, unheated and fermented cucumber mesocarp tissues stored at pH 3.5 had losses in galacturonic acid, galactose, arabinose, and rhamnose from cell walls isolated by sequential extraction with aqueous sodium dodecyl sulfate (SDS) and phenohacetic acid:water (2:1:1; SDS/PAW). Much smaller amounts of the sugars were solubilized when the cell walls were isolated by extraction with 80% ethanol. The differential solubilization of sugars suggested that a limited degradation of pectic and hemicellulosic substances occurred during cucumber tissue softening. This degradation was readily observed when softened tissue was extracted by SDS/PAW, but not when isolated by the more common ethanol extraction. Similarity in pattern of sugar losses, following low pH storage after three processing treatments, suggested that reactions which resulted in tissue softening and solubilization of cell wall sugars were similar in the three treatments.     

A qualitative assessment of Toxoplasma gondii risk in ready-to-eat smallgoods processing

Toxoplasma gondii is one of the most common parasitic infections of humans and other warm-blooded animals. In most adults, it does not cause serious illness, but severe disease may result from infection in fetuses and immunocompromised people. Consumption of raw or undercooked meats has consistently been identified as an important source of exposure to T. gondii. Several studies indicate the potential failure to inactivate T. gondii in the processes of cured meat products, This article presents a qualitative risk-based assessment of the processing of ready-to-eat smallgoods, which include cooked or uncooked fermented meat, paté, dried meat, slow cured meat, luncheon meat, and cooked muscle meat including ham and roast beef. The raw meat ingredients are rated with respect to their likelihood of containing T. gondii cysts and an adjustment is made based on whether all the meat from a particular source is frozen. Next, the effectiveness of common processing steps to inactivate T. gondii cysts is assessed, including addition of spices, nitrates, nitrites and salt, use of fermentation, smoking and heat treatment, and the time and temperature during maturation. It is concluded that processing steps that may be effective in the inactivation of T. gondii cysts include freezing, heat treatment, and cooking, and the interaction between salt concentration, maturation time, and temperature. The assessment is illustrated using a Microsoft Excel-based software tool that was developed to facilitate the easy assessment of four hypothetical smallgoods products.     

Influence of Microbial Growth on the Redox Potential of Fermented Cucumbers

ABSTRACT:  Commonly, pH measurements are used during the production of fermented cucumbers to indirectly monitor growth of lactic acid bacteria (LAB) and acid production. Redox potential (E_h) measurements, which are determined by the potential of an electron to reduce an acceptor, could serve as an alternative tool to monitor the progress of fermentation allowing the detection of the metabolic activity and/or growth of LAB and other microorganisms. Pasteurized and inoculated jars of cucumbers were observed to better understand how the E_h changes during the cucumber fermentation and how it could be used as a monitoring tool. Jars of diced, brined cucumbers were pasteurized and inoculated with microbes previously isolated from fermented cucumbers including Lactobacillus plantarum , Zygosaccharomyces globiformis , and Enterobacter aerogenes . Although an initial decrease in E_h was observed for all microorganisms, distinctive trends in E_h occurred when these organisms were inoculated. After a 2-wk fermentation period, the E_h (Ag/AgCl, 3 M KCl) in jars inoculated with L. plantarum , Z. globiformis , and E. aerogenes was at +453 ± 55, +104 ± 5, and –156 ± 73 mV, respectively. Cucumbers inoculated with a mixture of L. plantarum and Z. globiformis had a terminal E_h value of +202 ± 24 mV, which was between that found for the individual microorganisms. L. plantarum dominated the E_h trend when inoculated along with E. aerogenes with a final E_h of +411 ± 72 mV. The results showed that changes in E_h continued after pH measurements became stable. Thus E_h measurement can provide a tool to continuously monitor microbial growth during the course of cucumber fermentations.     

Storage Stability of Vegetables Fermented with pH Control

Vegetables fermented by Lactobacillus plantarum with pH control were microbiologically stable during 12-months' storage in hermetically sealed jars at ca. 24°C provided all fermentable sugars were removed during fermentation, and the products were stored at pH 3.8 or below. Fermented green beans, cucumbers, red and gieen bell peppers, and green tomatoes were thus rendered microbiologically stable. Fermented red beets and carrots, which contained residual sucrose, underwent secondary fermentation. Calculated carbon recoveries of the fermented vegetables ranged from 74–146%.