Effect of starter culture and inulin addition on microbial viability, texture, and chemical characteristics of whole or skim milk Kefir

Abstract

The effect of inulin addition and starters (Kefir grains or commercial starter culture) on the microbial viability, texture, and chemical characteristics of Kefir beverages prepared with whole or skim milk was evaluated during refrigerated storage. The type of starter did not influence microbial viability during the storage of the beverages, but the chemical and textural changes (decreases in pH, lactose concentration, and inulin and increased acidity, firmness, and syneresis) were more pronounced in the formulations fermented with grains than those fermented with the starter culture. The addition of inulin did not influence acidity or viability of lactic acid bacteria, but in general, its effect on the survival of acetic acid bacteria, Lactococcus and yeasts, firmness, and syneresis depended on the type of milk and starter culture used. Generally, the yeast, acetic acid bacteria, and Leuconostoc counts increased or remained unchanged, while the total population of lactic acid bacteria and Lactococcus were either reduced by 1 to 2 logs or remained unchanged during storage.

A review: chemical, microbiological and nutritional characteristics of kefir

“…Uraz, Akkuzu, Özcan, and Sevimay (2012) detected C. kefyr and C. famata as the most abundant species in kefir samples. Montanuci, Pimentel, Garcia, and Prudencio (2012) reported that yeast, acetic acid bacteria, and leuconostoc counts at the end of storage had either risen or changed only marginally, while those of LAB and Lactococcus were decreased or changed only marginally compared with those at the beginning of storage. They found that the acidity of kefir fermented with grains increased during storage, whereas no change in acidity was observed in beverages fermented with a starter culture.…”

Instrumental texture and sensory evaluation of fermented dairy beverages processed with reconstituted goat whey powder and a co-culture of Streptococcus thermophilus and Lactobacillus casei

“…The progressive fermentation of lactose due to active metabolism of the added cultures can result in post acidification reducing the pH (L obato Calleros et al, 2014), which can in turn result in textural changes (Montanuci et al, 2012) and syneresis (L ucey, 2004). Such changes affect negatively the products' quality and reduce it's shelf life (Zhao et al, 2006).…”

“…In some cases, the increased acidification affected the products' sensory features, reducing their acceptability (Behrens, 2002;Correa et al, 2008) or preference in relation to similar products with a less intense acid taste (Buriti et al, 2008). It is also known that progressive acidification in dairy products can modify their texture throughout the storage (Montanuci et al, 2012). In that manner, it is important to monitor such parameters during the storage of goat whey beverage added of a L. casei strain.…”

The infl uence of the dose of calcium bisglycinate on physicochemical properties, sensory analysis and texture profi le of kefi rs during 21 days of cold storage

“…Serum separation occurs as a result of aggregation of protein particles during storage and sedimentation under gravity. Stabilizers, acidity, total solids, milk and culture type can also aff ect the whey leakage in fermented milk beverages (Montanuci et al, 2012). Montanuci et al (2012) observed that an increase of syneresis was noted in kefi rs fermented with kefi r starter culture compared to beverages fermented with kefi r grains.…”