Comparative investigation of physico-chemical and sensory properties of glazed and non-glazed frozen rainbow trout (Oncorhynchus mykiss) thawed with different methods by principal component analysis

Quality of glazed (G) and non-glazed air-blast frozen rainbow trout (Oncorhynchus mykiss) was evaluated after applying different modern (M: microwave oven; U: ultrasonic; HVEFT: high voltage electrical field; O: ohmic heating) and conventional (S: steam cooking; W: water; R: refrigeration) thawing methods. Glazed frozen samples thawed by modern and conventional methods showed an increase in protein and pH contents (except for M/MG). The glazing process negatively affected the TVB-N (total volatile basic nitrogen) and % FFA (free fatty acid) levels and these compound increased after glazing in all thawed samples except for SG and S from  conventional and M, MG, U and UG from modern thawing methods, respectively. The TOTOX value of HVEF, HVEFG and OG was not significantly changed after thawing process compared with the fresh fish sample. Glazing could reduce the drip loss and increase the WHC (water holding capacity) in different thawing methods except for MG. MG and HVEFG/RG/WG had the lowest and highest hardness, respectively. The L* values of HVEF/HVEFG and U were higher than those of fresh and other thawing methods.