Formulation and Characterization Of The Nutritional; Physicochemical, Sensory and Shelf Life Properties Of Chia Enriched Yoghurt

Abstract

Yoghurt is a fermented dairy product associated with several beneficial nutritional and health effects. Due to increased demand of yoghurt in Kenya, some processors seek to incorporate artificial and highly processed ingredients such as stabilizers and emulsifiers as additives in order to improve nutritional value, thickening and stabilizing properties. Besides having good gelling properties, chia seeds (Salvia hispanica L.) are a good source of proteins, omega- 3/omega-6 fatty acids, minerals, soluble dietary fiber and phytochemicals. This study sought to develop chia enriched yoghurt and determine the nutritional (amino acids, fatty acids, mineral and vitamin C contents), physicochemical (pH, total titratable acidity and syneresis), sensory and shelf life characteristics of chia enriched yoghurt (CEY). The treatment involved enriching yoghurt with varied amounts of chi a seeds as follows; 1.5% m/v (CEY 1.5), 2.5% rn/v (CEY2.5), 3.5% m/v (CEY3.5), and corn starch (2%) (CEYO). The results of the proximate composition indicated there was a significantly higher content of moisture, crude ash, crude fat, crude fiber and carbohydrates in CEY 1.5, CEY2.5 and CEY3.5 than those of CEYO. In the current study, the nutritional composition was significantly higher in CEYI .5, CEY2.5 and CEY3.5 than in CEYO with regards to amino acids, fatty acids, minerals and vitamin C, with values increasing with increase in quantity of chia seeds in the formulation. The concentration of !auric acid and palmitic acid decreased significantly, between CEYO and all chia enriched samples (CEYI .5, CEY2.5 and CEY3.5), with the increase in the concentration of chia seeds in the yoghurt formulations. On the other hand, the concentration of stearic acid, oleic acid, linoleic acid and a-linolenic acid gradually increased significantly, as the quantity of chia seeds used in the yoghurt enrichment increased with CEY3.5 recording the highest concentration and CEYO the lowest. The results of physicochemical characteristics showed chia seeds had no effect on the pH and titratable acidity values of the yoghurt. From the results of sensory analysis, the panelists preferred the texture, taste, colour and appearance of CEYO and CEYI.5 over those of CEY2.5 and CEY3.5. In shelf life studies, pH decreased significantly while titratable acidity and syneresis increased significantly during refrigerated storage in both CEYO and all the CEY. In conclusion, CEYI .5, CEY2.5 and CEY3.5 showed enhanced nutritional (amino acids, fatty acids, minerals and vitamin C contents), physicochemical (pH and titratable acidity) and sensory properties compared to CEYO thus chia seeds could be a potential ingredient in yoghurt formulation