Determination of the nutrition value and shelf life of crayfish (Astacus leptodactylus) prepared by cook-chill method

The aim of this research is to investigate the effects of three different cooking methods (BC: boiled, SVC: sous vide, MC: microwave) on the nutritional value and shelf life of crayfish during cold storage. In the study, the yield percentage was found by calculating the post-cooking weight loss of crayfish cooked with three different methods. Moisture (%) measurements were carried out periodically during cold storage in the analysis samples in order to monitor the moisture change. In order to determine the nutritional value of raw (FC) and cooked crayfish (BC, SVC, MC), percent nutrient composition (crude protein, crude oil, raw ash, moisture) analyzes were performed and carbohydrate and energy values were calculated. Fatty acid, amino acid, mineral and vitamin analyzes were performed to reveal the nutritional composition values of raw (FC) and cooked crayfish (BC, SVC, MC). To determine the shelf life, during the cold storage period of the control groups (VP: vacuum packaged control group, MP: microwave packaged control group) and cooked groups (BC, SVC, MC); sensory, physico-chemical (pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), thiobarbituric acid (TBA)) and microbiological (total mesophilic aerobic bacteria (TMAB), total psychrophilic aerobic bacteria (TPAB), yeast, mold, total coliform, E.coli, Salmonella spp., Listeria spp., sulfite-reducing anaerobic bacteria) analyzes were performed. In the cooked crayfish groups (BC, SVC and MC), it was determined that the lowest cooking loss was 2.71% in the SVC group crayfish after the cooking process. Yield percentages of SVC, MC and BC crayfish groups were determined as 97.29%, 96.27% and 94.40%, respectively. A decrease in moisture, ash and carbohydrate percentages, and an increase in crude fat and crude protein percentages were observed in all three cooking methods. Depending on the cooking method, the highest increase in protein was found in the SVC crayfish group with 1.55%, and the highest increase in fat was found in the MC crayfish group with a rate of 1.06%. It was found that the main saturated fatty acids of raw crayfish tail meat were palmitic (18.10%) and stearic (11.40%) acids, and the total saturated fatty acid (ƩSFA) ratio was 36.43%. Monounsaturated fatty acids were found to be palmitoleic (4.26%) and oleic (16.04%) acids, and the total monounsaturated fatty acid (ƩMUFA) ratio was 21.93%. The polyunsaturated fatty acids (ƩPUFA) of crayfish were linoleic (4.73%), arachidonic (7.70%), eicosapentaenoic (7.75%) and docosahexaenoic (2.26%) acids and total polyunsaturated fatty acid (ƩPUFA) ) rate was determined to be 24.67%. It was determined that the total monounsaturated fatty acid (MUFA) ratio of all cooked crayfish increased after cooking, there were losses in total PUFA fatty acids, and the highest loss occurred in SVC group crayfish with a rate of 23%. In raw crayfish tail meat (FC), the major free amino acids were glutamic acid, alanine, aspartic acid, glycine, arginine, and tyrosine; In essential amino acids, it was determined that the most dominant amino acids were leucine and lysine. The ƩEAA/NEAA ratio of the cooked crayfish groups (BC, SVC and MC) was found to be between 0.81-0.98 g/100g It has been determined that the most dominant mineral substances in raw crayfish tail meat are calcium, zinc, magnesium, potassium, selenium, manganese, iron, copper, phosphorus and sodium elements. After the cooking processes applied to the crayfish, it was determined that the amounts of macro and micro elements decreased significantly and the highest loss of mineral matter was sodium (p<0.05). After cooking, an increase in the iron and copper content of MC group crayfish and lithium content of MC and BC group crayfish, while a significant decrease in copper content after cooking of SVC group crayfish was detected (p<0.05). The predominant vitamins of raw crayfish tail meat are vitamins B12, B3, and E, and they were found to be at the levels of 1.02 µg/100g, 2.43 mg/100g and 3.49 mg/100g, respectively, in crayfish meat. Significant reductions in the vitamin content of all cooked crayfish (BC, SVC and MC) (except vitamin B12) were determined compared to raw crayfish. Although vitamin B12 is an important water-soluble vitamin, a significant increase (p<0.05) was detected in crayfish cooked in boiling water (BC) and cooked in sous vide (SVC). It was determined that crayfish cooked in sous vide had the highest protein content, and crayfish cooked in microwave had the most favorable essential amino acid (EAA) ratio. For this reason, it has been revealed that these two methods are the cooking methods that best preserve the nutritional value of crayfish. Physico-chemical, microbiological and sensory quality changes were analyzed periodically during cold storage (2±0.7°C) in crayfish meat, which was applied to three different cooking (BC, SVC, MC) and then blast-chilled. All of the cooked crayfish are suitable for food safety, and no microorganism growth was found in any of the analyzes of Salmonella spp, Listeria spp, and sulfur-reducing anaerobic bacteria at the beginning and after 28 days of cold storage. On the 1st day of cold storage, total coliform levels were found to be 1.03 and 1.66 log cfu/g in the vacuum packed (VP) and microwave packed (MP) control groups, respectively. Total coliform bacterial load in MC, SVC, BC cooked crayfish groups was determined as ˂1 log cfu/g on day 1. E. coli results are; 0.61 and 0.41 log cfu/g in the VP and MP control groups on the 1st day of cold storage, and in the MC, BC and SVC cooked crayfish groups; It was determined that they were 0.12, 0.13 and 0.52 log cfu/g. It was determined that the total mesophilic aerobic bacteria (TMAB) and total psychrophilic aerobic bacteria (TPAB) counts of the cooked crayfish groups (BC, SVC and MC) were still at acceptable levels on the 21st day of cold storage. Yeast results in the control groups (VP and MP) on day 1 of cold storage were 1.85 and 2.40 log cfu/g, respectively. Yeast values of all cooked crayfish groups were determined as ˂1 log cfu/g. Mold values of both control and cooked crayfish groups were found to be ˂1 log cfu/g on the 1st day of storage, and yeast and mold values were determined to be ˂5 log cfu/g on the 21st day of storage. The total volatile basic nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) analysis results obtained in the study support each other, and the TMA-N values of SVC, BC and MC crayfish groups reached the limit values with 10.01, 10.13 and 11.42 mg/100g levels on the 28th day of cold storage. TVB-N values of SVC, BC and MC crayfish groups on the 28th day of cold storage; It reached the limit values with 35.50, 36.50 and 35.22 mg/100g levels. Thiobarbituric acid (TBA) values (4.79, 5.22, 5.69 mg MDA/kg) of the BC, SVC, MC groups during 28 days of cold storage compared to the TBA values of the control groups (VP: 7.87 mg MDA/kg, MP: 8.11 mg MDA/kg) was not found to be high. This result obtained in the cooked crayfish groups was interpreted as the cooking process could prevent possible lipid peroxidation in the product. According to panelist sensory evaluation of crayfish with different cooking methods, it was reported that the most liked product in terms of taste and aroma were sous vide, boiled in boiling water and microwaved crayfish, respectively. After 21 days of cold storage, they were found to be suitable for consumption in terms of sensory, chemical and microbiological analysis, while SVC and BC crayfish groups were found to be "consumable crayfish", except for the sensory evaluation of the MC crayfish group. After 28 days of cold storage (2±0.7°C), it was determined that all cooked crayfish groups (BC, SVC and MC) were "non-consumable products" unsuitable for human consumption and food safety in terms of sensory, physico-chemical and microbiological quality.