Yogurt Enriched with Chia Seeds: Physicochemical, Microbiological, and Sensory Changes during Storage
Gjore Nakov, Nadya Ninova-Nikolova, Nastia Ivanova, Violeta Raykova, Biljana Trajkovska, Mirela Lučan Čolić, Jasmina Lukinac, Marko Jukić
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.