The Effect of Addition of Berry Fruits on Antioxidant Activity and Bacteria Viability of Probiotic Yoghurt
Project no. 22869 · Status: Kapanmış · 2021
Summary
<p> In this study, the effect of addition with three different berries (raspberry, blueberry or goji berry) marmalade on the chemical, microbiological, textural, color and sensory characteristics and antioxidant properties of probiotic yoghurt, containing <em>Lactobacillus acidophilus</em> and <em>Bifidobacterium animalis</em> subsp. <em>lactis</em>, was investigated during 21 days of storage. Probiotic yoghurt without fruit marmalade constituted the control group in the study.</p><p> The viability of <em>Lactobacillus bulgaricus</em> and <em>Streptococcus thermophilus</em> in probiotic yoghurts were at least 7.5 log cfu/g throughout storage. The addition of raspberry, blueberry and goji berry marmalade to yoghurt generally did not significantly affect the viability of yoghurt bacteria compared to control yoghurt.</p><p> The numbers of <em>B. lactis</em> and <em>L. acidophilus</em> in probiotic yoghurt varieties provided the minimum recommended viability for probiotic bacteria (106-107 cfu/g) throughout storage. In addition, both probiotic bacteria did not show a significant decrease at the end of storage. The addition of berry marmalade significantly increased the viability of <em>B. lactis</em> in yoghurt samples on the 14 th and 21 st days of storage while the viability-enhancing effect of goji berry addition came to the fore at the end of storage. The addition of berry marmalade on the 1 st and 7 th days of storage significantly increased the numbers of <em>L. acidophilus</em>. It was determined that raspberry and goji berry fruits were more effective on L. acidophilus viability on most days of storage.</p><p> The most popular probiotic yoghurt for sensory properties was the sample added with raspberry marmalade whereas the highest viscosity and water holding values were determined in the yoghurt with goji berry marmalade. The addition of berry fruit marmalade also significantly affected the color properties of probiotic yoghurt during storage.</p><p> The highest total phenolic content was determined in probiotic yoghurt with goji berry during storage. Goji berry marmalade added yoghurt had also the highest DPPH radical scavenging capacity during the first 14 days of storage while no statistical difference was found among the probiotic yoghurts on 21st day. The amount of pelargonidin-3-glycoside, which can be used as an indicator of the total anthocyanin amount in fruit yoghurts, was found to be higher in the sample with blueberry addition than in the sample with raspberry during storage. Anthocyanin, in terms of the pelargonidin-3-glycoside, could not be determined in probiotic yoghurt with goji berry marmalade. The utilization of Goji berry in the production of probiotic yogurt is expected to provide a positive contribution to functional food manufacturing.</p>