Comparison of non-contact blanching and traditional blanching pretreatment in improving the product quality, bioactive compounds, and antioxidant capacity of vacuum-dehydrated apricot

Abstract

Browning and loss of bioactive compounds during thermal dehydration are critical problems associated with food product processing. The aim of this study was to develop and compare an innovative non-contacted blanching (NB) method with traditional hot water or steam blanching (SB) methods. The NB method not only requires less equipment but is also more efficient and can reduce the nutrient loss associated with traditional blanching. Our study found that NB is efficient in inhibiting enzyme activity and can retain more bioactive compounds (total polyphenols, total flavonoids, total carotene, ascorbic acid, protocatechuic acid, (+)-catechin, chlorogenic acid, and quercetin-3-rutinoside). Because of the higher content of bioactive compounds, the antioxidant capacity was also higher after treatment using the NB method than traditional methods. Thus, the NB blanching method may have potential applications in the food processing industry to improve the quality of food products in an economically viable manner. Practical applications Some regular problems such as browning and loss of nutrients are encountered in all thermal dehydration methods. Traditional water blanching can inactivate enzymes responsible for deterioration reactions in dehydrated products but it can directly lead to nutrient loss in hot water. Although the steam blanching (SB) method is not associated with the problems mentioned above, its efficiency is inconsistent and the equipment cost is higher than that for water blanching. Hence, the non-contact blanching (vacuum packing blanching) was compared with the traditional method in terms of nutrient retention and quality improvement. This non-contact blanching method cannot only achieve the purpose of inactivating enzymes as in traditional water or SB to improve quality but also maximizes the protection of bioactive compounds. In addition, because of the high cost of traditional non-contact blanching, this study aimed to find an efficient and low-cost alternative method to these methods.