Changes in nutritional value and application of thyme (Thymus vulgaris) essential oil on microbial and organoleptic markers of Persian clover (Trifolium resupinatum) sprouts

• Germination caused a 1.5-fold increase in antioxidant activity of Persian clover.
• All measured organic acids and minerals (except K) increased, as sprouting progressed.
• Polyunsaturated fatty acids decreased while oleic acid increased 3.4% compared to raw seed.
• Thyme essential oil was effective to control the population of different microbial groups of clover sprouts.
• Total aerobic for stored 2% essential oil (7.9 log10 CFU/g) was even lower than that of fresh control (9.1 log10 CFU/g).

In this study, effect of the 4-day germination on the chemical composition, antioxidant activity and fatty acids profile of Persian clover seeds (Trifolium resupinatum) was investigated. In addition, clover sprouts was immersed in 0.5, 1 and 2% thyme (Thymus vulgaris) essential oil (EO) solutions, packaged in polyethylene containers and stored at refrigerated temperature (4 °C) for 10 days. As seedling progressed, the moisture, protein, crude fibre and ash content increased, whilst fat and carbohydrate reduced. After 4-day germination, ascorbic acid, total phenolic content and antioxidant activity indicated 1.3, 2 and 1.5 fold increase, respectively. Sprouting caused significantly (p < 0.05) increase in measured organic acids and minerals (except K). Moreover, oleic acid showed an increase of 3.4% compared to raw seed. In respect to microbial quality, the treated clover sprout demonstrated a significant reduction in the population of total aerobic bacteria, coliforms, molds and yeast count followed by increasing EO concentration compared to the control. Total aerobic bacteria, total coliforms, molds and yeast count of clover sprouts with 2% thyme EO showed 3.2, 2.3 and 2.2 log10 unit reduction, just after treatment. During storage, the population of natural microflora increased significantly (p < 0.05) in all treatments.