The investigation of the effect of freezing pretreatment on properties of black garlic produced from Kastamonu garlic

Abstract

Black garlic is obtained by fermentation of fresh garlic in condition under controlled high humidity and temperature.The aim of this study is to investigate the effect of freezing as pre-treatment process on black garlic produced from fresh Kastamonu garlics in terms of various antioxidant activity parameters, phenolic and flavanoid contents, fermentation time and HMF formation. The antioxidant properties analysis results of frozen and non-frozen black garlic samples were shown that higher than those of white garlic and it was observed that total antioxidant capacity, the total phenolic compound and total flavanaoid content values of black garlics increase with the storage period under fermentation conditions. In addition, frozen garlics were found to have higher total antioxidant activities on the 25th and 30th days (9.56 mg AE/g and 10.40 mg AE/g, respectively) of the fermentation than the activities of non-frozen garlics the on the 35th day (8.49 mg AE/g) of fermentation. The toxic compound HMF formation was found of the frozen sample at as high as 110 mg/kg in end of the 35th day. In conclusion, the use of pre-frozen garlics in black garlic production will be more efficient in respect of antioxidant properties and time and cost saving.