Effect of Freezing Pretreatment on the Processing Time and Quality of Black Garlic

Abstract

AbstractBecause freezing treatment can destroy the cell structure of garlic, we investigated the effect of freezing pretreatment on black garlic processing with the traditional processing method as contrast. Results showed that freezing for 30 h had the greatest impact on the reducing sugar content. The control garlic processing 21–24 days had the best quality. Freezing pretreatment can affect the black garlic quality through the browning degree, reducing sugar content, amino‐N content, total phenolic content and 5‐hydroxymethyl‐2‐furaldehyde (5‐HMF) levels. The freezing garlic had a faster color change than control samples. When the processing ended, the reducing sugar content, total phenols content and 5‐HMF content of freezing pretreated garlic were increased by 51.88, 58.54, 25%, respectively, compared with the control samples. The amino‐N content of freezing‐pretreated garlic decreased 50.97% compared with the control one. The results indicated that freezing pretreatment can promote the generation of functional materials.Practical ApplicationsAlthough garlic has been used worldwide as food or herbal supplement, some people feel discomfort because of its strong pungent odor. Black garlic is one of the garlic‐processed products, eliminating its stimulating odor. However, the quality of black garlic products on the market is varied and the processing time is long. As is known, freezing is widely used to destroy cell structure. In the present study, the use of freezing pretreatment in black garlic processing can promote the generation of functional materials and significantly reduce processing time from 60–90 to 22 days. These provided potential method to the black garlic processing.