Evaluating microwave energy impact on 3G snacks: A study on dielectric properties and expansion

Third-generation (3G) snacks, a food type of widespread interest in the industry, have a longer shelf life than second-generation (2G) snacks. The primary regeneration process for these snacks involves frying and microwaving. However, only a few studies have detailed the effects of microwave irradiation on these products. This study aims to analyse the influence of the type of material, compression, and microwave power on the expansion capabilities of the pellets. Four raw materials (rice flour, rice semolina, corn semolina, and wheat starch) were combined with water to achieve uniform moisture content and extruded into pellets with different compression ratios (1:1, 2:1, and 3:1). The elaborated samples were processed at different microwave powers (heating rates of 2 and 10 °C/s) using an instrument capable of accurately delivering microwave energy to food samples while monitoring key process parameters, including dielectric properties. Samples with high starch content, low protein content, and low fibre content, in conjunction with higher compression ratios exhibited a more pronounced expansion.