The effect of adding some herbs (green tea, mint, thyme, rhubarb) and grape seed extracts on various properties of yogurt and its oxidoreduction

In this study, yogurt was enriched with green tea waste fiber (Camellia sinensis; 0.5%, ethanol:water 100:0), Mint (Mentha piperita L.; 0.1%, ethanol:water 50:50), Thyme (Thymus vulgaris L.; 0.1%, ethanol:water 70:30), Rhubarb (Rheum ribes L.; 0.1%, ethanol:water 50:50), Grape seed (Vitis vinifera ssp vinifera, 0.1%, E:W 70:30) extracts. Total phenolic content, antioxidant activity (DPPH, ABTS) determination, determination of phenolic components, analysis of volatile components, acidification and reduction capacity, pH and oxidoreduction potency (Eh7), titration acidity determination, dry matter determination, syneresis determination, color determination, carbohydrate and organic acid analysis, microbiological analysis, viscosity analysis, texture analysis and sensory analysis were applied to the obtained extract and the yoghurts produced in this way stored at +4 °C in the 1st, 7th, 14th and 21st days of storage. It was determined that in addition to the physical, chemical, volatile component analysis results, oxidoreduction potential and microbiological properties of the plant extracted yogurts changed significantly with storage and these changes were statistically significant (p< 0.05). While Lactobacillus delbrueckii subsp. bulgaricus (LB) reduction activity changed slighlty in milk enriched with any plant extract; Streptococcus thermophilus (ST) reduction activity is changed drastically. According to the results, it was revealed that plant extracts can be used as a natural antioxidant source in changing the oxidoreduction potential in yogurt formulas, the oxidoreduction potential is important in taking into account the quality control in yogurt.