Physicochemical, Microbial and Sensory Properties of Yoghurt Supplemented with Flaxseed during Storage

Ng, Tjia Ee (2020) Physicochemical, Microbial and Sensory Properties of Yoghurt Supplemented with Flaxseed during Storage. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

With the ever-increasing awareness of consumers towards the importance of having a healthy diet, functional foods are quickly gaining popularity amongst consumers. Flaxseed is a topic of interest as it has a multitude of health benefits such as potentially providing anti-inflammatory, anti-oxidative and lipid profile modulation effects. Yoghurt is another popular example that reduces pathogenic bacteria growth and colon cancer risk, and it is rich in nutrients such as essential amino acids (EAA) and minerals. In this study, the control sample was cow’s milk yoghurt, while the experimental samples were incorporated with 2% ground flaxseed (w/w) and 4% ground flaxseed (w/w). Their physicochemical properties and microbial viability was studied for 2 weeks. Proximate analysis showed that moisture content of the samples ranged from 76.69% to 79.54%, and 4% flaxseed yoghurt sample has the highest crude protein, fat, ash and fibre content. All samples differ significantly at p<0.05. The pH of the yoghurt samples ranged from 4.24 to 4.63. Meanwhile, the titratable acidity values ranged from 1.06 to 2.00 % over 2 weeks’ storage, and viability of probiotics (Streptococcus thermophilus, L. acidophilus and L. bulgaricus) remained in range of 107 and 108 CFU/mL. These values are acceptable as they were in range. Total soluble solid content of samples does not differ much significantly. The viscosity of 4% flaxseed yoghurt was found to be the highest while control sample was the lowest. Syneresis decreased for all samples, with the 4% flaxseed yoghurt having the least. Sensory evaluation showed all samples’ sensory attribute mean scores ranged from 5.44 to 7.22, and that 2% flaxseed yoghurt was most preferred by panellists based on appearance, aroma, taste and overall acceptability. Meanwhile, control yoghurt was most preferred in terms of its texture with mean score of 6.56 ± 1.49.