No abstract

To improve the texture quality of blue honeysuckle berry (BHB) snack under continuous microwave puffing and obtain suitable process parameters, the effects of technology parameters, such as microwave intensity, ventilation velocity, and puffing time, on the objective indexes in terms of temperature, moisture content, expansion ratio, porosity, hardness, and brittleness of BHB snack were investigated via response surface method and pore distribution analysis. The results showed that microwave intensity and puffing time had the highest effects for the objective indexes.The formation of texture quality of snack depended on the structure and distribution of internal pores inside the product. The optimal parameters for continuous microwave of snack were obtained as the microwave intensity of 9.23 W/g, ventilation velocity of 0.76 m/s, and puffing time of 3.26 min to produce a desirable texture quality.This study may provide guidance for the industrial production development of novel snack products for berry fruits like BHB. Novelty impact statement:This work investigated the puffed BHB snack under continuous microwave puffing and optimized the process parameters to achieve a desirable texture quality. Microwave intensity lower than 10 W/g achieved desired texture quality with suitable hardness and brittleness of BHB snack. The size and distribution of internal pores determined the formation of texture quality of BHB snack.

Blueberry extract contains diversiform monomers of anthocyanins, whose antioxidant activity determines the functionality of anthocyanidins and the efficacy of extraction technology. The evaluation of the antioxidant activity of anthocyanidins of blueberry ethanol extracts (BEE) was investigated by considering the monomers' identification and thermal degradation in microwave-assisted extraction (MAE). Thirteen monomers of anthocyanins were identified from the extracts of blueberry under MAE, where the highest content was for cyanidin glycosides, and the lowest content was for the malvidin glycosides. The onset temperatures of degradation for anthocyanidins monomers in BEE were 41.07°C-48.50°C, and the glycoside contents of delphinidin, cyanidin, petunidin, peonidin, peonidin, and malvidin, in turn, decreased obviously. The degradation of anthocyanidins with extraction temperature improved, other than weakened, its antioxidant activities in BEE under MAE. The research results may provide valuable guidance for the antioxidant application of extracts from blueberries.

Raspberry snack, as a novel berry product, has rich favor and high crisp taste, where controllable texture quality is conducive to the palatability of the snack. Determinative factors of microwave puffing in microwave intensity and durationand key property of material in Young's modulus were introduced to investigate the formation of texture quality of berry snack under microwave puffing. The results indicate that the microwave intensity has negative correlation with Young's modulus of raspberry chips, which causes the more porosity inside under microwave puffing. Reasonable Young's modulus of raspberry chips enhances the interior porosity and exterior expansion volume of raspberry snack due to the water vapor wrapped other than escaped. The greater microwave intensity results in the higher volume expansion of raspberry chips, in which the great volume expansion from porous pores structure confers moderate hardness. In microwave puffing, the formation of hardness and crispness of raspberry snack depend on microwave puffing parameters, leading to high temperature and great dehydration rate in quick puffing duration, in addition to Young's modulus of raspberry chips, where high dehydration rate accelerates water removal inside raspberry chips to form a harder texture with decreasing springiness, whereas low dehydration rate leads to the gentle change of springiness. Raspberry snack with uniform internal pores and regular shape forming desirable texture may be achieved under the microwave intensity of 7.5 W/g and the puffing duration of 6 min. This study indicates that high-quality raspberry snack may be achieved via controlling heating rate in microwave puffing.

No abstract