Assessment of Freeze-Dried Immobilized Lactobacillus casei as Probiotic Adjunct Culture in Yogurts

Abstract

Freeze-dried immobilized Lactobacillus casei ATCC 393 on casein and apple pieces were assessed as a probiotic adjunct culture for novel probiotic yogurt production. The effect of probiotic culture on physicochemical characteristics, probiotic cell survival, volatile aroma compounds, and sensory quality were evaluated during 28 days of storage at 4 °C. The use of L. casei resulted in lower pH values (3.92–4.12), higher acidity (0.88–1.10 g lactic acid/100 g of yogurt), and lower syneresis (40.8%–42.6%) compared to traditionally produced yogurt (pH 4.29; acidity 0.83 g lactic acid/100 g of yogurt; syneresis 44.1%). Microbiological and strain-specific multiplex PCR (Polymerase Chain Reaction) analysis confirmed that immobilized L. casei ATCC 393 cells were detected in yogurts at levels >7 log cfu g−1 after 28 days. In addition, probiotic supplementation significantly affected the concentrations of key volatile compounds, like acetic and other organic acids, 2-ethyl-1-hexanol, acetoin, and 2-butanone, as revealed by GC-MS (Gas Chromatography–Mass Spectrometry) analysis. Finally, the sensory evaluation demonstrated that the new products exhibited improved characteristics compared to traditionally produced yogurts.

Yogurts Supplemented with Juices from Grapes and Berries

“…Since the nature of the culture provides a low content of L. bulgaricus , the present study focused only on the trend of S. thermophilus viability during processing and storage. The numbers of L. bulgaricus decreased as was also reported in numerous studies with yogurts [ 35 ] and especially in samples with fruit juices [ 48 ].…”

“…These values are attributed to the low pH value of the juices used. The maximum rate of pH decline, in all cases, occurred between 1 and 2.5 h after milk inoculation, which is faster compared to previous studies [ 35 ] and may be attributed to different starter culture. The use of different juices had no significant effect on the milk acidification rate and the small differences observed were not important from a technological point of view.…”

“…This defect may limit the shelf life of the product and affects its acceptability by the consumers due to the undesirable appearance. Usually, the consumers correlate syneresis with potential microbial infection of the yogurt [ 20 , 24 , 35 ]. Previous studies have correlated the addition of fruit juices with reduced viscosity and increased syneresis of yogurts [ 19 , 20 ].…”

Tarkhineh as a new microencapsulation matrix improves the quality and sensory characteristics of probiotic Lactococcus lactis KUMS-T18 enriched potato chips

“…However, probiotics are sensitive to the loss of cell water during the lyophilization process and also this process has a low efficiency during long storage. This method has been widely used to stabilize probiotic bacteria in dairy and non-dairy products such as apple snacks 17 , soy bars 18 , sausages 19 , chocolate 20 and many dairy products 21 . However, applying this technique for use in potato chips is not very effective 22 .…”

Characterization and production optimization of a broad-spectrum bacteriocin produced by Lactobacillus casei KLDS 1.0338 and its application in soybean milk biopreservation

“…[20][21][22][23] Furthermore, L. casei have proven to show beneficial probiotic properties, such as antioxidative activity, tumorinhibitory, reduction of cholesterol, and improvement of gastrointestinal microflora. [24][25][26] Previous studies indicated that L. casei strains can be used as food biopreservative (and replace chemicals) and potentially alleviate/prevent gastrointestinal foodborne pathogen infections. It has also demonstrated the successful application of L. casei and their bacteriocins against foodborne pathogens and food spoilage in fermented food.…”