Black garlic production: The influence of ageing temperature and duration on some physicochemical and antioxidant properties, and sugar content

Herein, some quality characteristics (water content, pH, antioxidant activity and sugar contents) of fresh garlic (Taşköprü, Türkiye) and black garlic, which were produced under various ageing temperatures (60 °C, 70 °C and 80 °C) and durations (30, 45 and 60 days), and the effect of ageing processes on these quality characteristics were determined. The ageing process caused a reduction (P < 0.01) in the water content and pH value of the samples, while enhanced (P < 0.01) antioxidant activity and increased (P < 0.01) the content of glucose, fructose, sucrose and reducing sugar. Both the water content and pH value of the black garlic declined significantly with increasing ageing temperature, while only pH value of the black garlic declined significantly with increasing ageing duration. Ageing samples at 60 °C and 70 °C exhibited higher antioxidant activity than those aged at 80 °C, which had similar activity to the fresh samples. A similar status was observed when the ageing temperature was prolonged to 60 days. Sucrose concentration of the black garlic samples raised with elevating the ageing temperature and declined with prolonging the duration. While a remarkable decline in the reducing sugars of the black garlic samples was observed with elevating the ageing temperature, the maximum concentration was recorded on the 45th day of the ageing process. However, the black garlic samples produced at 60 °C for 60 days or 70 °C for 30 days could be recommended to get a final product with good antioxidant capacity, adequate amount of free sugars, pH value and water content.