## 1 Introduction  
White shrimp (_Litopenaeus vanname_) is an important crustacean introduced worldwide since the 1970s, and its cultivation has been growing in Asia since 2000 [1]. Its production in Taiwan is approximately 80,000 metric tons annually [2]. White shrimp is an excellent source of several nutrients including peptides, proteins, enzymes, polysaccharides, mineral, and essential amino acids, which can be beneficial for the health of the consumer [2]. Most white shrimp are generally consumed in its cooked form, and in Taiwan, cooking is done largely by boiling in water [2]. Cooking can deactivate polyphenol oxidase and protease, and destroy some pathogens and spoilage bacteria, thereby maintaining the quality of shrimp [3, 4]. Microwave (MW) heating has some merits such as a reduced processing time, a fast heating rate, and reduced destruction of nutrients and flavors in food [5]. As MW ovens are usually easy to handle and have a low maintenance cost, MW heating has become popular in the food processing field including for cooking, drying, preservation, and pasteurization of foods [6]. Nevertheless, the non-uniformity of temperature distribution is a primary disadvantage of MW heating, which can often create cold and/or hot spots in the food [7]. The coldest location in food by MW heating can result in serious food safety concerns [8]. Thus, combining MW with other conventional heating methods can effectively overcome the drawbacks of the MW technique [9]. These combinations, namely the MW-assisted (MA) processing technique such as MA-infrared heating, MA-vacuum frying, MA-oven drying, MA-freeze drying, and MA-steam heating, have been widely applied in food processing [9]. In the last few years, an emerging thermal processing technology, MA thermal sterilization (MATS), or MA pasteurization was developed by the research group in Washington State University [10]. In MATS and MA pasteurization, prepackaged food placed in a soft bag is heated in pressurized hot water or MW-heated at a frequency of 915 MHz to perform rapid sterilization or pasteurization, respectively. In particular, the utilization of heated water as an intermediate can overcome the concerns of non-uniform heating and reduce edge heating in food packages by using MW heating [11]. MATS has been used to study the thermal treatments of foods including asparagus, macaroni and cheese, salmon, chicken, mashed potatoes, and sliced beef [7]. In Taiwan, [PERSON] et al. [12] developed an experimental and small scale MA induction heating (MAIH) system consisting of two heating components. In detail, the MW heating unit is in the top half of the machine, whereas the electromagnetic induction heating unit is in the bottom half of the machine. Before heating, the raw food ingredient is put into a heat-resistant container and then sealed with a heat-resistant film. The induction half-cavity consists of tight-fitting top and bottom chambers. The container is first placed in the induction half-cavity and then in the place of induction heating half-cavity and heated by the MAIH system [12]. Recently, this first generation and experimental MAIH was used to cook and pasteurize shrimp for the first time [13]. However, this was small-scale equipment with a sample capacity of approximately 350 mL, which cannot achieve an economical scale. Therefore, the second generation enlarged MAIH machine was designed with a sample capacity of approximately 1.0 L, consistent with the commercial scale (Figure 1). The purpose of this study was to investigate whether in comparison to the experimental MAIH, the scaled-up MAIH machine could achieve the desirable seafood cooking performance. In addition, to our knowledge, there is no research regarding the application and use of a scaled-up MAIH on heating prepackaged shrimp. Therefore, in this study, a scaled-up MAIH was used for heating prepackaged shrimp, immediately after which the quality attributes of the product including the appearance, color, texture, and microbiological quality were evaluated.