Abstract
The improvement of milk dairy products’ quality and nutritional value during shelf-life storage is the ultimate goal of many studies worldwide. Therefore, in the present study, prospective beneficial effects of adding two different industrial yeasts, Kluyveromyces lactis and Saccharomyces cerevisiae pretreated by heating at 85 °C for 10 min to be inactivated, before fermentation on some properties of ABT fermented milk were evaluated. The results of this study showed that the addition of 3% and 5% (w/v) heat-treated yeasts to the milk enhanced the growth of starter culture, Lactobacillus acidophilus, Bifidobacteria, and Streptococcus thermophilus, during the fermentation period as well as its viability after 20 days of cold storage at 5 ± 1 °C. Furthermore, levels of lactic and acetic acids were significantly increased from 120.45 ± 0.65 and 457.80 ± 0.70 µg/mL in the control without heat-treated yeast to 145.67 ± 0.77 and 488.32 ± 0.33 µg/mL with 5% supplementation of Sacch. cerevisiae respectively. Moreover, the addition of heat-treated yeasts to ABT fermented milk enhanced the antioxidant capacity by increasing the efficiency of free radical scavenging as well as the proteolytic activity. Taken together, these results suggest promising application of non-viable industrial yeasts as nutrients in the fermentation process of ABT milk to enhance the growth and viability of ABT starter cultures before and after a 20-day cold storage period by improving the fermented milk level of organic acids, antioxidant capacity, and proteolytic activities.
Highlights
In recent years, many studies have demonstrated the relation between the increased consumption of fermented and/or functional foods and a decrease in the predisposing of several diseases [1]
The modified functional foods include a wide range of ingredients, such as probiotics, prebiotics, vitamins, and minerals, which are found in different dairy products, such as fermented milks [2]
The results indicated that the mean values of viable counts of Lb. acidophilus, Bifidobacterial sp., and St. thermophilus were increased at the end of the fermentation period conducted at 40 ◦ C for 4 h (Figure 1A)
Summary
Many studies have demonstrated the relation between the increased consumption of fermented and/or functional foods and a decrease in the predisposing of several diseases [1]. Functional foods have recently gained growing interest as healthy foods in many countries as they have a therapeutic effect on the health of consumers [1]. The modified functional foods include a wide range of ingredients, such as probiotics, prebiotics, vitamins, and minerals, which are found in different dairy products, such as fermented milks [2]. A probiotic microorganism is defined as a viable microbial dietary supplement to food that beneficially affects the host through its effects in the intestinal tract [3,4]. Lactis BB-12 and different strains of Lactobacillus acidophilus have many health beneficial effects toward the host, such as enhancement of the immune system [6], reduction of endotoxemia, attenuation of gut The probiotics bacterium Bifidobacteria animalis subsp. lactis BB-12 and different strains of Lactobacillus acidophilus have many health beneficial effects toward the host, such as enhancement of the immune system [6], reduction of endotoxemia, attenuation of gut
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