REGULAR ARTICLE EFFECTS OF DRYING METHODS ON PHYSICO-CHEMICAL, MICROBIOLOGICAL AND SENSORY PROPERTIES OF TORPEDO SCAD (Megalaspis cordyla) Md. Golam Rasul 1 , Ilias Ebne Kabir 1 , Chunhong Yuan 2 , A. K. M. Azad Shah* 1 Address(es): Prof. A. K. M. Azad Shah 1 Bangabandhu Sheikh Mujibur Rahman Agricultural University, Faculty of Fisheries, Department of Fisheries Technology, Gazipur 1706, Bangladesh. 2 Iwate University, Faculty of Agriculture, Department of Food Production and Environmental Management, 3-18-8 Ueda, Morioka 020- 8550, Japan. *Corresponding Author: azad@bsmrau.edu.bd ABSTRACT Generally, fish are unhygienically sun dried, which causes the considerable reduction of quality and safety of the product. The effects of drying methods on physico-chemical, microbiological, and sensory properties of Megalaspis cordyla were investigated. Fish were dried using traditional (without pre-treatment), improved (treated with 5% salt solution), improved-TC (treated with 5% salt solution and rubbed with turmeric and chili powder) and solar tunnel (treated with 5% salt solution) drying methods. Sensory evaluation revealed that solar-dried products showed comparatively better quality than the products produced by other drying methods. Rehydration ability of solar dried products was comparatively higher than other dried products. Moisture content of dried M. cordyla was ranged from 16.28% to 21.30%. However, no significant (p > 0.05) variation was found in protein, lipid and ash content on dry matter basis. Significantly (p < 0.05) the lowest peroxide value, acid value and carbonyl value were observed in solar dried products. In contrast, comparatively higher amount of PUFAs were found in solar dried products followed by improved, improved-TC and traditionally produced dried fish. The aerobic plate count of dried M. cordyla varied between 2.04 log CFU/g and 5.71 log CFU/g. Results of this study suggested that the dried fish produced by solar tunnel drying method showed comparatively better quality than other drying methods for the consumer’s safety. Keywords: Megalaspis cordyla, drying methods, sensory properties, chemical composition, fatty acid, lipid oxidation INTRODUCTION Sun drying is a traditional and important processing method to preserve seafood since ancient times. Different drying methods have different effects on dried fish. During the drying process, seafood is exposed to light, heat, and air, which can affect the nutritional quality of the product. For domestic market, about 20% of the artisanal catch is being dried by traditional sun drying method (Hasan et al., 2016a) and Bangladesh earns 425.20 million BDT of foreign currency by exporting 3143.93 metric ton of dried fish in the year of 2017-18 (DoF, 2018). However, sensory and nutritional quality of those dried products are not satisfactory for human consumption due to unhygienic processing and handling of fish, inappropriate drying methods and time, insects’ infestation, microbial and fungal growth, indiscriminate use of various types of pesticides, improper storage and lipid oxidation of dried fish (Reza et al., 2005; Chaijan et al., 2006; Hasan et al., 2016b; Rasul et al, 2020). Lipids of marine fish are rich in n-3 long chain polyunsaturated fatty acids (Aidos et al, 2002; Passi et al, 2002) are very prone to oxidation that is also favored by sun drying. Lipid oxidation has an important role to change the quality and safety of products. Besides, lipid oxidation products have adverse effects on human body (Larsson et al., 2015; Bellanti et al., 2017). Now-a-days, people are more concerned about the health and nutritive value of the food product when they buy them for their consumption (Hossain et al., 2008; Bhuiyan et al., 2008). Therefore, fish processors should be aware about processing time, technique and finally the nutritional quality and safety of the dried products. To improve the quality of dried fish, various drying techniques have been established with diverse pre- treatments. During drying of fish, powdered chili pepper and turmeric powder have been reported to be used against insect infestation (Nowsad, 2005; Rahman et al., 2017). In addition, solar tunnel drying method is used to produce quality dried fish, which do not need any power from electrical grid or fossil fuels (Nowsad, 2003). Different kinds of solar tunnel dryer have been designed and examined for fish drying (Ogbonnaya, 2009). Thus, a suitable drying method of fish is crucial to improve nutritional value by retarding the microbial growth and lipid oxidation. Furthermore, it is necessary to ensure quality and safe dried fish for the consumers as well as earning more foreign currencies. Torpedo scad, Megalaspis cordyla (locally known as Kauwa fish) is belongs to the family of Carangidae, mostly found in coastal and marine waters in Bangladesh. The taste of this fish is very poor that is why consumers do not prefer to eat it although the price of this fish is comparatively cheaper than other marine fishes. Generally, many people do not like to eat some marine fish species as fresh but they prefer these fish as dried for its characteristic taste and flavor. So far, there is no dried fishery products prepared from this species. Thus, there is an opportunity to produce dried product of this species that might improve the quality and taste of the final products and it might be a value addition of this species. Therefore, this study was aimed to investigate the effects of drying techniques on the physico-chemical, microbiological and sensory characteristics of M. cordyla. MATERIALS AND METHODS Fish samples collection Fresh Torpedo scad, M. cordyla (length 25.76 ± 5.32 cm and weight 413.36 ± 9.81 g) were bought from the local fish market, Gazipur, and were brought with proper icing to the Fish Processing Laboratory of Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh. Drying methods M. cordyla was dried using four different methods of drying- namely traditional sun drying, sun drying on ring tunnel dryer, sun drying on ring tunnel dryer with turmeric and chili powder, and solar tunnel drying, which are designated as traditional, improved, improved-TC and