Shelf life of Bottled Sea Squirt Halocynthia roretzi Meat Packed in Vegetable Oil (BSMO)

Fresh sea squirt meat requires a modified processing and preservation process because it has a short shelf life due to its high moisture content and strong proteolytic enzyme activity. In this study, bottled sea squirt meat prepared in vegetable oil (BSMO) to enhance the consumer acceptability was exposed to ${\gamma}$-ray (Co60, 10 kGy/h) irradiation to extend the shelf life without the use of a heating process. Response surface methodology was used to determine the optimal mixing ratio of BSMO containing 5% dehydrated fresh meat. Texture analysis and nutritional evaluation were also performed on a control and BSMO samples. The volatile basic nitrogen (VBN) content and total cell count were measured to determine the shelf life of irradiated BSMO products during chilled storage at $4^{\circ}C$ for 60 days. According to a panel of 10 trained tasters (aged 20-29 years), the optimal mixing formulation was 80 g meat in 60 mL of mixed vegetable oil (30 mL of olive oil and 30 mL of sesame oil). The highest rated formulation, according to a panel of nine trained tasters (aged ${\geq}30$ years), was 80 g meat in 60 mL of mixed vegetable oil (42 mL of olive oil and 18 mL of sesame oil). Moisture, ash, and protein contents in BSMO did not change significantly (P < 0.05) compared with the control. A higher lipid content ($0.84{\pm}0.23$ to $2.13{\pm}0.61$; P < 0.05) was observed due to the presence of vegetable oil on the surface of BSMO. The vegetable oil raised the hardness, springiness, cohesiveness, gumminess, chewiness, and resilience of BSMO. BSMO products remained edible after 50 days of storage at $4^{\circ}C$ based on the VBN content (BSMO 1: $27.92{\pm}0.96$ mg/100 g, BSMO 2: $24.84{\pm}1.95$ mg/100 g) and total cell count (BSMO 1: $4.60{\pm}0.80$ log CFU/mL, BSMO 2: $3.65{\pm}0.20$ log CFU/mL) when compared with standard levels of VBN (25.00 mg/100 g) and total cell count (5 log CFU/mL), respectively. The results showed that irradiated BSMO products could help to expand the processed seafood market and increase the popularity of seafood among the younger generations.