Yogurt Enriched with Chia Seeds: Physicochemical, Microbiological, and Sensory Changes during Storage

Abstract

This study investigates the physicochemical, microbiological, and sensory properties of yogurt fortified with honey and chia seeds at concentrations of 5% and 10% (w/w) over a 21-day storage period at 4 ± 1 °C. The addition of chia seeds resulted in initial pH increases, with 5% and 10% chia seeds having pH values of 4.22 ± 0.02 and 4.31 ± 0.01, respectively, compared to 4.20 ± 0.01 for the control yogurt. During storage, the pH decreased by 0.17 units for the control yogurt and by 0.08 and 0.13 units for 5% and 10% chia seeds, respectively. The titratable acidity (TA) increased significantly, by 9.1% for the control yogurt and by 22.9% and 29.6% for the 5% and 10% yogurt, respectively. The protein content increased from 3.22 ± 0.03 g/100 g in the control sample to 3.92 ± 0.08 g/100 g and 4.59 ± 0.00 g/100 g for 5% and 10% chia seeds, respectively, without any significant changes during storage. The number of lactic acid bacteria (LAB) was highest in the control sample (9.005 ± 0.007 log CFU/g) and lowest in the 10% yogurt with chia seeds (8.495 ± 0.007 log CFU/g), with all samples remaining free of harmful microorganisms. The sensory evaluation showed that yogurt with 5% chia seeds received the highest overall acceptability scores, while yogurt with 10% chia seeds had poorer scores for taste and texture. Overall, fortification of yogurt with 5% chia seeds improves its nutritional value and sensory properties without compromising product safety or microbiological quality.