Increase in conjugated linoleic acid content and improvement in microbial and physicochemical properties of a novel kefir stored at refrigerated temperature using complementary probiotics and prebiotic

Hamid Pourbaba,Amir Ali Anvar,Hamed Ahari,Rezvan Pourahmad

doi:10.1590/fst.61520

Hamid Pourbaba, Amir Ali Anvar + Show 2 more

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https://doi.org/10.1590/fst.61520

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Abstract

Abstract The present study was aimed to determine the effects of Lactobacillus acidophilus LA-5, L. paracasei 431, and Bifidobacterium lactis BB-12 with lactulose on values of conjugated linoleic acid (CLA) and microbial, physicochemical, and sensory properties of a novel kefir. Thirteen groups were evaluated on days 1, 7, and 14 at 4 oC. The interaction between probiotics and lactulose reduced pH to 4.5 in the first week and slightly decreased on day 14 (4.35). The syneresis value was decreased by increasing the lactulose dose. The interaction could not remarkably increase probiotic survival; the greatest and lowest values were 7.18 and 7.81 log CFU/mL, respectively. The greatest and the lowest lactic acid value was 2.77 and 1.47 g/100 mL, respectively, in kefirs supplemented with L. acidophilus LA-5 and L. acidophilus LA-5+ L. paracasei 431+ B. lactis BB-12. A 4-fold increase in the acetic acid value (0.592 g/100 mL) was observed in kefirs supplemented with B. lactis BB-12 along with L. acidophilus LA-5 and L. paracasei 431 (G12). It is concluded that adding 5% lactulose along with L. acidophilus LA-5+ L. paracasei 431 to kefir could valuably increase the CLA value (3.51-8.07 ppm) and give it more acceptability of flavor, odor, and syneresis.

Highlights

Probiotics are living cells and usually modify food contents for health benefit of humans (Roobab et al, 2020)
Kefir is a complex-probiotic produced from corresponding grains (Demirci et al, 2019; Kivanc & Yapici, 2019; Tomar et al, 2020) that encompass a consortium of microorganisms (Lim et al, 2019; Mitra & Ghosh, 2020), such as lactic acid bacteria (LAB) containing Lactococcus, Lactobacillus, occasionally acetic-acid producing bacteria, and non-lactose fermenting yeast, with a long-endured association with a natural substance matrix of proteins and kefiran as polysaccharide (Bengoa et al, 2019b; Rosa et al, 2017; Tomar et al, 2020)
The probiotic count (PC) range was 7.25-7.82 log CFU/mL on day 14 of preservation of the kefir at 4 °C (Table 2). This result (Table 2) was not in concordance with that obtained by Delgado-Fernández et al (2019), who reported that the number of Lactobacillus spp reached 9.1 and 9.3 log CFU/mL on days 7 and 14 at refrigerated temperature in kefir supplemented with 2-4% lactulose

Summary

Introduction

Probiotics are living cells and usually modify food contents for health benefit of humans (Roobab et al, 2020). L. acidophilus is one of the homofermentative bacteria which directly produce two lactic acid (LA) molecules from one molecule of glucose (Fazio et al, 2020), but heterofermentative ones, including B. lactis, convert glucose to lactic acid and acetic acid (AA) or other volatile compounds (Zareba et al, 2012). The biological and physico-chemical criteria of fermented milk beverages are essential for the ultimate properties of the product. These properties are associated with the milk content, starter type and volume, complementary probiotics, fermentation temperature, and acidity (Wang et al, 2017). Titratable acidity (TA) and pH are two key indicators measured to determine the quality of milk during kefir production. Lactic acid and acetic acid indicate the quality of the kefir, measuring them is costly and requires more technique (Magalhães et al, 2011b)

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