Standardisation of coconut milk enriched yoghurts

Abstract

Yoghurt is a fermented dairy product produced by the action of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus on milk. Yoghurt is widely recognised for its rich nutritional profile, health promoting benefits and functional properties that support digestive and immune health. The present study was undertaken to standardise coconut milk yoghurt and to develop fruit pulp incorporated coconut milk yoghurts using mango, guava and sapota. The study also aimed to evaluate the physicochemical, nutritional, organoleptic and shelf life qualities of the selected yoghurts. Coconut milk yoghurts (CMY) were prepared by replacing cow’s milk in different proportions. Ten treatments were evaluated for various organoleptic qualities and were compared with 100 per cent milk yoghurt (control). Yoghurt with 60% coconut milk and 40% cow milk (T6) was the most acceptable treatment with a total organoleptic score of 50.20. It was selected along with the control (T0) for further evaluation over 15 days of refrigerated storage. Both treatments showed a gradual decline in sensory qualities over the storage period. The selected yoghurt treatment T6 had lower moisture (77.78%), acidity (0.61%), water holding capacity (48.21%), viscosity (9800 cP), curd tension (38.50 g), TSS (12.5°Brix), total sugar (8.5%), reducing sugar (3.9%), carbohydrate (4.50 g/100g), protein (2.28 g/100g), vitamin C (0.21 mg/100g), total ash (0.61%), calcium (66.91mg/100g), phosphorus (42.72mg/100g), potassium (64.56mg/100g) and magnesium (6.35mg/100g), while it had higher pH (4.71), syneresis (2.0%), peroxide value (0.80), fat (12.10%), energy (136.02 Kcal) and iron (0.65mg/100g) content compared to control T0. Vitamin A was not detected in either sample. Most parameters showed slight changes during storage; however, the changes in moisture content and water holding capacity were statistically significant, whereas variations in other parameters were not significant after 15 days of refrigerated storage. The selected coconut milk incorporated yoghurt (T6) was enriched with mango pulp (MP), guava pulp (GP) and sapota pulp (SP) in varying levels. One yoghurt from each fruit incorporated variant with the highest organoleptic acceptability score were selected, along with the control (CMY - 60%coconut milk + 40% cow milk), for further studies. Among the mango pulp incorporated yoghurts, treatment T3 (CMY + MP 15%) achieved the highest total organoleptic score of 51.11 and was selected for further studies. Similarly, T3 (CMY + GP 15%) from the guava incorporated, with a score of 50.44, and T4 (CMY + SP 20%) from the sapota incorporated, with a score of 47.40, were also selected and stored at refrigerated temperature for 15 days along with the control for further studies. Incorporation of fruit pulp into yoghurt significantly altered its physicochemical and nutritional properties, enhancing both functionality and nutrient content. Among the fruit incorporated yoghurt variants, sapota yoghurt exhibited the highest values for several parameters, including moisture content (79.96%), pH (4.87), viscosity (10300 cP), peroxide value (0.78 meq/kg), total soluble solids (15°Brix), total sugars (13.6%), reducing sugars (7.8%), energy content (136.99 Kcal), carbohydrates (5.30 g/100g), and fat (11.91%). Mango yoghurt showed the highest acidity (0.56%), curd tension (32.50 g), protein content (2.20 g/100g), and vitamin A (10.5 IU). Guava yoghurt recorded the highest water holding capacity (50.80%) and vitamin C (0.85 mg/100g). These findings highlight the influence of fruit type on yoghurt’s nutritional and functional qualities, offering valuable insights for product development and targeted health benefits. In all treatments, including fruit pulp incorporated and control yoghurts, E. coli, coliforms and fungi were absent throughout the storage period. Yeast was not detected up to the 10th day, but contamination by yeast was observed on the 15th day of storage. The cost of production of selected coconut milk incorporated (CMY - 60%coconut milk + 40% cow milk) yoghurt was 30.00 rupees per 100ml and for fruit incorporated it varied from 32.00 to 36.00 rupees per 100ml. The standardised products represent a novel category of yoghurts with strong potential for commercialisation and diversification, offering valuable opportunities for developing value added yoghurt alternatives