Search

• Fermentation of rosmarinic acid and lemon balm extract was performed. • Eleven commercially available probiotics were used. • Rosmarinic acid highly degrades, depending on probiotic strains used. • The compound is more stabile in pure form than in extract matrix. • Lactobacillus helveticus is presumed responsible for extensive degradation. Rosmarinic acid (RA) represents a phenolic compound with numerous proven health benefits. However, peroral application limits its effectiveness, due to degradation occurring inside digestive tract. The aim of the research was to investigate in vitro stability of RA under the fermentative activity of microorganisms present in intestinal microbiota. Pure compound and lemon balm extract were used as sources of RA, while the source of microorganisms were 11 commercially available probiotics containing preparations. The concentrations of RA before and after fermentation were determined by high performance liquid chromatography (HPLC-DAD). Reduction of RA's content was significant in some of used probiotics, ranging from approximately 20% to total 100% in case of pure compound use. In cases of use of same probiotic supplement, decrease in RA's content is higher in case of lemon balm extract. The bacterial strain found responsible for higher extent of degradation was Lactobacillus helveticus. During fermentation process, various metabolites can be formed, including caffeic and ferulic acid, while other compounds detected in lemon balm's extract were also susceptible to microbial fermentation. Rosmarinic acid degrades extensively during fermentation by microorganisms present in intestinal flora. This compound is more stable in pure samples than in complex matrix of extract. [ABSTRACT FROM AUTHOR]

Pulque is a Mexican alcoholic, probiotic beverage with shelf life of 3 days. The physicochemical, probiotic, and sensory properties of pulque depend on its content of lactic acid bacteria (LAB) and yeasts. The aim of this study was to apply ohmic heating (OH) in order to extend the shelf life of pulque without altering its properties. Pulque processed by conventional pasteurization (63 °C, 30 min) was used as control. Parameters such as electrical conductivity (0.22 S/m) and optimal pasteurization conditions by OH (65 °C, 5 and 7 min; 70 °C, 3 and 5 min) were determined. Shelf life was evaluated with these parameters during 22 days of storage at 4 ± 1 °C. A higher content of LAB (6.68 and 5.96 log10 CFU/mL) was obtained at 65 °C for 5 and 7 min, respectively, compared with conventional pasteurization (3.54 log10 CFU/mL). After 22 days, physicochemical properties (pH, color, and alcohol content) were stable for both methods of pasteurization. However, the pulque treated with OH had greater sensory acceptance. For the first time, OH was used to process pulque, and results revealed that is an effective technology for extending the shelf life until 22 days, preserving microbiological and physicochemical properties. Microorganisms as surviving the OH treatments were identified as Lactobacillus acidophilus, Lactobacillus kefiri, and Saccharomyces cerevisiae. [ABSTRACT FROM AUTHOR]

Abstract: Yeasts are unicellular eukaryotic microorganisms isolated from many foods, and are commonly found in table olive processing where they can play a double role. On one hand, these microorganisms can produce spoilage of fruits due to the production of bad odours and flavours, the accumulation of CO2 leading to swollen containers, the clouding of brines, the softening of fruits and the degradation of lactic acid, which is especially harmful during table olive storage and packaging. But on the other hand, fortunately, yeasts also possess desirable biochemical activities (lipase, esterase, β-glucosidase, catalase, production of killer factors, etc.) with important technological applications in this fermented vegetable. Recently, the probiotic potential of olive yeasts has begun to be evaluated because many species are able to resist the passage through the gastrointestinal tract and show beneficial effects on the host. In this way, yeasts may improve consumers'' health by decreasing cholesterol levels, inhibiting pathogens, degrading non assimilated compounds, producing antioxidants and vitamins, adhering to intestinal cells or by maintaining epithelial barrier integrity. Many yeast species, usually also found in table olive processing, such as Wicherhamomyces anomalus, Saccharomyces cerevisiae, Pichia membranifaciens and Kluyveromyces lactis, have been reported to exhibit some of these properties. Thus, the selection of the most appropriate strains to be used as starters, alone or in combination with lactic acid bacteria, is a promising research line to develop in a near future which might improve the added value of the commercialized product. [Copyright &y& Elsevier]

The use of Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technique in identifying the microorganisms present in commercial probiotic yoghurts and lyophilised products was evaluated. Two reference ladders were assembled constituted by PCR-amplified V2–V3 regions of 16S rDNA from bacterial species generally used as probiotics. Identification was achieved comparing the PCR-DGGE patterns obtained from the analysed products with the ladder bands. Bands from members of the same species showed the same migration distance in denaturing gel, hence supporting the identificative value of the method. The validity of the technique was also proven confirming the PCR-DGGE identification results by sequence data analysis and by species-specific PCR. General congruence between microorganisms declared on the label and those revealed by PCR-DGGE was found for probiotic yoghurts. Conversely, some discrepancies were observed for probiotic lyophilised preparations, i.e. the incorrect identification of some Bifidobacterium and Bacillus species and the presence of not declared microorganisms. PCR-DGGE turned out to be an appropriate culture-independent approach for a rapid detection of the predominant species in mixed probiotic cultures. [Copyright &y& Elsevier]