Improvement of Pacific White Shrimp (Litopenaeus vannamei) Drying Characteristics and Quality Attributes by a Combination of Salting Pretreatment and Microwave

Abstract

This study investigated the effects of salting pretreatment and microwave (MW) power on drying characteristics, water distribution and quality attributes of Pacific white shrimp (Litopenaeus vannamei). With increasing salt concentration (0–8%, w/v) and MW power (300–900 W), the drying time of shrimp was shortened by 15.15–28.57%, compared with the untreated samples. Regarding the quality of dried shrimp, increasing the salt concentration and MW power increased the hardness (from 13,073.6 to 24,556.5 g), while the springiness, color parameters and astaxanthin content showed an initial decrease but a later increase trend. Low field nuclear magnetic resonance (LF-NMR) demonstrated that the T2 curve of the pretreated samples moved toward the negative x-axis and the immobilized water content decreased with increasing salt concentration. E-nose showed that volatile components were different and could be obviously distinguished at different salt concentrations and MW powers. Raman spectroscopy illustrated that the protein secondary structure of dried shrimp was altered by salting pretreatment and drying conditions, and the lowest conversion degree of α-helix to β-sheet of dried shrimp was obtained at the salt concentration of 4% (w/v) and MW power of 500 W. By comprehensively considering the drying time and quality attributes, the combination of 4% (w/v) salt and 500 W MW power was concluded as the best drying conditions for shrimp using a microwave. The results could provide an innovative combination of salt pretreatment and MW drying with suitable processing conditions for producing high-quality dried shrimp.

A systematic review of drying in aquatic products

“…To overcome the shortcomings of MD, some studies have focused on the advanced technologies that can improve drying efficiency and quality attributes. Such as salting pretreatment, 13 spouted bed, 57 and vacuum technique 58 . It is widely recognised that MD under vacuum helps lower drying temperature and increase drying efficiency.…”

“…However, the drying process changes the quality of aquatic products because of protein denaturation, oxidation and hydrolysis, 10 lipid oxidation and hydrolysis, 11 and browning is violently happening during the drying process of aquatic products, 12 resulting in significant changes in the physical and chemical properties, nutritional components and flavour composition. Therefore, pretreatments before drying are often adopted to improve the quality of aquatic products and reduce energy consumption, such as salting, blanching, ultrasound, high pressure and chemical treatment 13 . Compared with developed countries, these developing countries, like African and southeast Asian countries faced more drying technologies issues.…”

“…Therefore, pretreatments before drying are often adopted to improve the quality of aquatic products and reduce energy consumption, such as salting, blanching, ultrasound, high pressure and chemical treatment. 13 Compared with developed countries, these developing countries, like African and southeast Asian countries faced more drying technologies issues. At present, natural drying (ND), salted drying (SD) and hot air drying (HAD) are the two most widely used technologies for aquatic products with low cost.…”

Evaluation of Aroma Characteristics of Dried Shrimp (Litopenaeus vannamei) Prepared by Five Different Procedures

“…It is favored by consumers due to its delicious meat and rich nutrition. After the fresh shrimp was dried, the storage period of the product could be extended, and the transportation cost of the product could be effectively reduced [ 1 ]. Because of its unique flavor and bright color, it was a great willingness by consumers and has been used in instant soup, fast food, and baby food.…”

“…The E-nose system is composed of a series of sensors and identification systems. The E-nose is convenient for preprocessing, has good repeatability and high sensitivity, and has been widely used to distinguish odor differences between different samples [ 1 , 6 ]. However, the E-nose system mainly analyzes the overall information of the sample and cannot obtain detailed information on volatile compounds.…”