Bioactivity, Physicochemical and Sensory Properties of Probiotic Yoghurt Made from Whole Milk Powder Reconstituted in Aqueous Fennel Extract

El Sayed Hassan Atwaa,Hayfa Hussin Ali Hijazy,El Sayed Abd El-Sattar,Ashraf Albrakati,Magdy Ramadan Shahein,Ehab Kotb Elmahallawy

doi:10.3390/fermentation8020052

El Sayed Hassan Atwaa, Hayfa Hussin Ali Hijazy + Show 4 more

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https://doi.org/10.3390/fermentation8020052

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Abstract

Fermented dairy products have long been associated with positive health benefits. The present study was undertaken to evaluate the physicochemical and sensory properties, viable probiotic counts, antioxidant activity and total phenolic content of probiotic yoghurt made by reconstituting of whole milk powder in aqueous fennel seed extract. Different concentrations of fennel aqueous seeds extract (2%, 4% and 6% w/v) were used as a substitute for water to reconstitute whole milk powder in formulations of yoghurt as functional additives. Interestingly, the use of aqueous extract of fennel seeds in the reconstituted yoghurt milk did not affect yoghurt composition (moisture, protein, fat and ash contents) compared to plain yoghurt. The titratable acidity significantly decreased after using aqueous fennel seed extract in the yogurt manufacture. In this regard, the titratable acidity value was 0.85 in the control yogurt at the fresh period and 1.14 after 21 days of storage, while this value significantly decreased in the yogurt treatments with 2%, 4% and 6% aqueous fennel seed extract to 80, 0.77 and 0.72, respectively, at fresh period and reached 1.03, 0.96 and 0.94, respectively, after 21 days of storage (p < 0.05). Conversely, the pH values significantly increased (p < 0.05) following the addition of aqueous fennel seed extract in the yogurt manufacture. Moreover, the total phenolic content significantly increased (p < 0.05) from 38.60 (mg GAE/L), in fresh plain yogurt, to 44.80, 53.20 and 64.30 (mg GAE/L), in 2% fennel extract yoghurt (FEY2), 4% fennel extract yoghurt (FEY4) and 6% fennel extract yoghurt (FEY6), respectively. Likewise, the antioxidant activity significantly increased (p < 0.05) from 0.11 (mM TE) in fresh plain yogurt to 0.18, 0.26 and 0.32 (mM TE) in (FEY2), (FEY4) and (FEY6), respectively. The survival of Lactobacillus acidophilus, Streptococcus thermophilus and Bifidobacterium bifidum decreased during storage time in all yoghurt treatments, although it stood at recommended levels for health effects (at least 106 cfu/mL in traditional yoghurt). For sensory evaluation, FEY4 was more acceptable, followed by FEY6, FEY2 and PY, respectively. Collectively, the present study provides useful information about the bioactivity, physicochemical and sensory properties of probiotic yoghurt made from whole milk powder reconstituted in aqueous fennel extract.

Highlights

The last few decades have witnessed there a growing interest in research concerned with the therapeutic effect of dairy products, those containing probiotics, which reduce symptoms associated with chronic diseases [1,2]
The aim of this study was to investigate the bioactivity, physicochemical and sensory properties of probiotic yoghurt made from whole milk powder reconstituted in aqueous fennel extract
These results are in line with those reported by Caleja et al [4], who found that the moisture content yoghurt at fresh time was 87.6% and reached 87.3%, after 14 days of storage

Summary

Introduction

The last few decades have witnessed there a growing interest in research concerned with the therapeutic effect of dairy products, those containing probiotics, which reduce symptoms associated with chronic diseases [1,2]. There is a growing interest in improving the nutritional and health value of fermented milk by incorporating probiotic bacteria with health benefits [6]. In this respect, some additives have been used in food industry to improve the characteristics and properties of processed foods. Several natural extracts such as herbs and fruits, which have health-promoting properties such as antioxidant and antimicrobial effects, have been used as natural additives during yogurt manufacture to improve the functional and nutritional value of the final product [11,12]. An increased demand for natural antimicrobial substances as alternatives to replace the additives, and replacing additives with herbal extracts in food products, has attracted remarkable attention [9]

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