Survival rate analysis of freeze-dried lactic acid bacteria using the arrhenius and z-value models

Probiotic sugar confectionery fortified with flax seeds (Linum usitatissimum L.)

People have affection for confectionary products. Confectionery products are of two types, baker and sugar confectionary. Dark chocolates belong to sugar confectionery class. The present invention was carried out on the preparation of synbiotic dark chocolates. Synbiotics are food products that contain both prebiotics and probiotic microorganisms, wherein prebiotics encourage the growth of probiotics. The synbiotic dark chocolates were amended with flax seeds (Linum usitatissimum L.) as a prebiotic for LAB. Flax seed contains fiber and phenolic antioxidants which makes them prebiotic source. The isolated LAB culture, which was identified as Leuconostoc mesenteroides based on morphological, biochemical tests and MALDI-TOF, showed the properties of a probiotic culture viz., tolerance to sodium chloride, bile salt, pH, and temperature, sensitivity to antibiotics, nonhemolytic and production of hydrogen peroxide. Cytotoxic activity of the cell free supernatant was assessed against MDA MB 231 and neuroblastoma cell line. Probiotic strain showed 48% and 30% cytotoxicity against MDA MB 231 and neuroblastoma cell line. The synbiotic chocolate was found to have more antioxidant activity, i.e. 90 U/mL by DPPH assay and 200 (μg Trolox/mL) by FRAP assay. The synbiotic chocolate prepared will be beneficial for the gut health of the humans and will also have excellent nutritional value.

Encapsulation of probiotics in soybean protein-based microparticles preserves viable cell concentration in foods all along the production and storage processes

The influence on the stability of Lactobacillus plantarum CECT 220 (25 °C/60% relative humidity) of microencapsulation by simple coacervation followed by spray-drying using different Ca²⁺-to-soybean protein isolate ratios was evaluated. After optimisation, the selected soybean protein concentrate (SPC) microparticles were used to evaluate the tolerance of L. plantarum under acidic conditions (lactic acid, pH = 4; and HCl, pH = 3) and heat stress (80 °C for 1 min) in contrast to free cells. Moreover, after the heat treatment, the influence of the simulated gastric fluid was evaluated. Additionally, different foods were formulated using either microencapsulated or freeze-dried L. plantarum, and the stability of cells during the shelf-life of the formulated foods was studied. Results show that encapsulation with SPC enhanced significantly the stability of the Lactic Acid Bacteria all along the probiotic food value chain, from production to the end of the food shelf-life.

Protective effect of sugars on storage stability of microwave freeze-dried and freeze-dried Lactobacillus paracasei F19

AIMS

Microwave freeze drying (MWFD) in comparison with conventional freeze drying allows for intensification of the preservation process of lactic acid bacteria without imposing additional processing stress. Viability as a function of storage time of microwave freeze-dried Lactobacillus paracasei ssp. paracasei F19 was investigated in comparison to conventionally lyophilized bacteria of the same strain. Furthermore, the impact of the protectants, sorbitol, trehalose and maltodextrin, on shelf life was analysed.

METHODS AND RESULTS

The highest inactivation rates of 0·035 and 0·045 day^-1 , respectively, were found for cultures without protectants. Thus, all additives were found to exhibit a protective effect during storage with inactivation rates between 0·015 and 0·040 day^-1 . Although trehalose and maltodextrin samples were in the glassy state during storage, in contrast to samples containing sorbitol as protectant, the best protective effect could be found for sorbitol with the lowest inactivation rate of 0·015 day^-1 .

CONCLUSIONS

Due to its low molecular weight, it might protect cells owing to better adsorption to the cytoplasma membrane. Sorbitol additionally shows antioxidative properties. Storage behaviour of microwave freeze-dried cultures follows the typical behaviour of a product dried by conventional lyophilization. No significant influence of the drying technique on storage behaviour was detected.

SIGNIFICANCE AND IMPACT OF THE STUDY

General findings concerning storage behaviour in freeze drying are likely to be applicable in MWFD with only slight adjustments.

Kefir Grains Change Fatty Acid Profile of Milk during Fermentation and Storage

Several studies have reported that lactic acid bacteria may increase the production of free fatty acids by lipolysis of milk fat, though no studies have been found in the literature showing the effect of kefir grains on the composition of fatty acids in milk. In this study the influence of kefir grains from different origins [Rio de Janeiro (AR), Viçosa (AV) e Lavras (AD)], different time of storage, and different fat content on the fatty acid content of cow milk after fermentation was investigated. Fatty acid composition was determined by gas chromatography. Values were considered significantly different when p<0.05. The highest palmitic acid content, which is antimutagenic compost, was seen in AV grain (36.6g/100g fatty acids), which may have contributed to increasing the antimutagenic potential in fermented milk. Higher monounsaturated fatty acid (25.8g/100g fatty acids) and lower saturated fatty acid (72.7g/100g fatty acids) contents were observed in AV, when compared to other grains, due to higher Δ9-desaturase activity (0.31) that improves the nutritional quality of lipids. Higher oleic acid (25.0g/100g fatty acids) and monounsaturated fatty acid (28.2g/100g fatty acids) and lower saturated fatty acid (67.2g/100g fatty acids) contents were found in stored kefir relatively to fermented kefir leading to possible increase of antimutagenic and anticarcinogenic potential and improvement of nutritional quality of lipids in storage milk. Only high-lipidic matrix displayed increase polyunsaturated fatty acids after fermentation. These findings open up new areas of study related to optimizing desaturase activity during fermentation in order to obtaining a fermented product with higher nutritional lipid quality.