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This research determined the concentration of trehalose, xylose and l -citrulline in fresh and fermented cucumbers and their utilization by Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus brevis and Lactobacillus buchneri. Targeted compounds were measured by HPLC and the ability of the lactobacilli to utilize them was scrutinized in fermented cucumber juice. Fresh cucumber juice was supplemented with trehalose, xylose and l -citrulline to observed mixed culture fermentations. Changes in the biochemistry, pH and colony counts during fermentations were monitored. Trehalose, xylose and l -citrulline were detected in fermentations to15.51 ± 1.68 mM, a fresh cucumber sample at 36.05 mM and in fresh and fermented cucumber samples at 1.05 ± 0.63 mM, respectively. Most of the LAB tested utilized trehalose and xylose in FCJM at pH 4.7. l -citrulline was utilized by L. buchneri and produced by other LAB. l -citrulline (12.43 ± 2.3 mM) was converted to ammonia (14.54 ± 3.60 mM) and the biogenic amine ornithine (14.19 ± 1.07 mM) by L. buchneri at pH 4.7 in the presence of 0.5 ± 0.2 mM glucose enhancing growth by 0.5 log CFU/mL. The use of a mixed starter culture containing L. buchneri aided in the removal of l -citrulline and enhanced the fermentation stability. The utilization of l -citrulline by L. buchneri may be a cause of concern for the stability of cucumber fermentations at pH 3.7 or above. This study identifies the use of a tripartite starter culture as an enhancer of microbial stability for fermented cucumbers.

The diversity and dynamics of the dominant bacterial population during the manufacture and the ripening of two artisanal Pecorino Crotonese cheeses, provided by different farms, were investigated by the combination of culture-dependent and -independent approaches. Three hundred and thirty-three strains were isolated from selective culture media, clustered using Restriction Fragment Length Polymorphism and were identified by 16S rRNA gene sequencing. The results indicate a decrease in biodiversity during ripening, revealing the presence of Lactococcus lactis and Streptococcus thermophilus species in the curd and in aged cheese samples and the occurrence of several lactobacilli throughout cheese ripening, with the dominance of Lactobacillus rhamnosus species. Bacterial dynamics determined by Denaturant Gradient Gel Electrophoresis provided a more precise description of the distribution of bacteria, highlighting differences in the bacterial community among cheese samples, and allowed to detect Lactobacillus plantarum, Lactobacillus buchneri and Leuconostoc mesenteroides species, which were not isolated. Moreover, the concentration of flavour compounds produced throughout cheese ripening was investigated and related to lactic acid bacteria presence. Fifty-seven compounds were identified in the volatile fraction of Pecorino Crotonese cheeses by Gas Chromatography-Mass Spectrometry. Esters, alcohols and free fatty acids were the most abundant compounds, while aldehydes and hydrocarbons were present at low levels.

An aseptic tank model system was used to study the efficacy of chlorine dioxide (ClO2) gas as a potential sanitizing agent for commercial epoxy-lined juice storage tanks. Selected spoilage micro-organisms (Lactobacillus buchneri, Leuconostoc mesenteroides, Eurotiumspp.,Penicilliumspp,Candidaspp. andSaccharomyces cerevisiae) were surface inoculated on to epoxy-coated stainless steel strips, placed in the model tank and subjected to different ClO2gas treatments. The varied treatment conditions consisted of 2–14 mg l−1ClO2gas, 50–98% relative humidity, 5–120 min exposure time, and temperatures ranging from 9–31°C.L. buchneriwas used as the target micro-organism and was found to be most resistant to selected ClO2gas treatments, followed byL. mesenteroides, followed by the yeasts and molds studied. Inactivation ofL. buchneriandL. mesenteroidesincreased with greater concentration of ClO2gas, higher holding temperature, higher relative humidity, and more exposure time. Under the conditions of this study, all the selected micro-organisms could be completely inactivated, resulting in a sterilized surface. The recommended treatments for assuring sterility were 10 mg l−1ClO2gas for an exposure time of 30 min coupled with (a) high relative humidity (>90%) and holding temperatures between 9 and 28°C, or (b) high holding temperatures (25–28°C) and relative humidity above 69%.

Changes during the spoilage of fermented cucumber pickles have been attributed to the metabolism of different yeasts and bacteria. In this study six organisms isolated from commercial spoiled cucumber pickles were evaluated for their possible role in primary and secondary cucumber fermentations. The ability of the yeasts Issatchenkia occidentalis and Pichia manshurica to utilize lactic and acetic acids during aerobic metabolism was confirmed and associated with increases in brine pH and the chemical reduction of the fermentation matrix. Lactobacillus buchneri and Pediococcus ethanolidurans were able to produce lactic acid from sugars, but only L. buchneri produced acetic acid at the expense of lactic acid under both aerobic and anaerobic conditions regardless of the initial acidic pH of 3.2 in the medium. The formation of secondary products was associated with the metabolism of Clostridium bifermentans and Enterobacter cloacae, which metabolic activity was observed at medium pH above 4.5. Individually, the selected spoilage microorganisms were found to be able to produce changes associated with secondary cucumber fermentations. The fact that oxidative yeasts and L. buchneri were able to produce chemical changes associated with the initiation of the spoilage process indicates that prevention of the secondary fermentation could be achieved by inhibiting these organisms.

Hydrocolloids improve the volume, texture, and shelf life of bread. Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) during sourdough fermentation can replace hydrocolloids. It was the aim of this study to determine whether heteropolysaccharides (HePS) synthesized intracellularly from sugar nucleotides by glycosyltransferases are produced in wheat and gluten-free sorghum sourdough at effective levels. The HePS-producing strains Lactobacillus casei FUA3185, L. casei FUA3186, and Lactobacillus buchneri FUA3154 were used; Weissella cibaria 10M producing no EPS in the absence of sucrose served as control strain. Cell suspensions of L. buchneri in MRS showed the highest viscosity at low shear rate. Glycosyltransferase genes responsible of HePS formation in LAB were expressed in sorghum and wheat sourdough. However, only HePS produced by L. buchneri influenced the rheological properties of sorghum sourdoughs but not of wheat sourdoughs. Sorghum sourdough fermented with L. buchneri exhibited a low |G ∗ | compared to the control, indicating a decrease in resistance to deformation. An increase in tan δ indicated decreased elasticity. The use of LAB producing HePS expands the diversity of EPS and increases the variety of cultures for use in baking.