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Influence of various health beneficial spices on some characteristics of yogurt culture bacteria and Lactobacillus acidophilus and sensory acceptability of spicy probiotic yogurt
Garlic and ginger have a beneficial influence on averting cardiovascular diseases. Onion and turmeric decrease the risk of diabetes and have anticancer properties. Streptococcus thermophilus, Lactobacillus bulgaricus and Lactobacillus acidophilus are lactic acid bacteria that produce lactase and reduce the symptoms of lactose malabsorption. Earlier work has shown the influence of spice extracts but the influence of pure spice juice on yogurt culture bacteria is not known. Characteristics of yogurt culture bacteria were measured by suspending freshly thawed cultures into 0.1% peptone water (growth), MRS-Thio broth with oxgall (bile tolerance) and skim milk (protease activity) with 1% (v/v) of freshly extracted spice juice. Fresh spices were obtained locally and spice juice was extracted using a juice extractor. Bile tolerance was measured by enumeration in presence of bile and protease activity was measured by a spectrophotometric assay. A probiotic blueberry yogurt was made that incorporated 0.05% of individual spice juice. Apparent viscosity of probiotic blueberry yogurt was measured using a viscometer with a helipath and Wingather 32 software. A T-C spindle was used at 20 rpm and 100 data points were acquired per sample. Physico-chemical characteristics of spicy probiotic yogurts containing the three bacterial cultures used were determined. Differences of least square means were used to determine significant differences at P < 0.05 for main effects and interaction effects. Consumer acceptability test was conducted using 100 consumers. A nine point scale was used to evaluate overall appearance, color, aroma, taste, texture and overall liking of the product. Results indicated that all spices except turmeric improved the bile tolerance of L. bulgaricus. Ginger, turmeric and onion had the best overall influence on the protease activity of S. thermophilus. Turmeric improved the protease activity of L. bulgaricus. Ginger and turmeric improved the protease activity of L. acidophilus. All four spices decreased the pH of the spicy yogurt, while garlic, ginger and turmeric increased the titratable acidity of the spicy yogurt. Onion and ginger increased the apparent viscosity of the spicy yogurt. The control yogurt obtained 80% acceptance and the ginger yogurt obtained 84% acceptance, and both of these yogurts obtained the highest intent of purchase. Ginger can be used in spicy yogurt manufacture for direct consumption while all 4 spices have potential for a new product line of yogurts for cooking, marinating and dips enabling potential health benefits from both spices and probiotic bacteria.
Keywords: spice, fermented, culture