Rainbow trout (Salmo irideus) produced in Finland VII. Changes in the organoleptic quality and fetty acid composition during frozen storage

Abstract

Until now freezing has been one of the most important means of storing fish. Several investigators have tried to solve the problems connected with the changes in the fish protein during frozen storage (Cowie et al. 1966, Olley et al. 1967).Changes in the lipid fraction of the fish may be of equal importance in lowering the quality of the fish, especially fatty fish, during frozen storage. The purpose of this study was to examine the effect of two different storage temperatures and two different means of packaging upon the organoleptic quality and the fatty acid composition of frozen rainbow trout. Material and methodsThe experiments were carried out with second-summer rainbow trout fed with Clark dry food for rainbow trout. The average weight of the fishes was 130 grams (from 85 to 201 grams) and the control fishes were transported to the laboratory alive. The rest of the fishes were killed and gutted and frozen rapidly at -40°C. One half of the fishes were glazed with water while the second half was individually packed in vacuum sealed polyethylene bags. The fishes were then transported to the laboratory in styrox containers into which CO a-ice had been added. The fish arrived at the laboratory 18 hours after gutting. At the laboratory the samples were divided again into two halves with storage temperatures of 18 and 32°C. For the organoleptic evaluation samples were taken from the control fish after 1 day, 1 week, 1 month and 3 months, and for the fatty acid analyses from the control fish after 1 day, 1 week, 1 month and 7 months.The organoleptic evaluation was performed according to Niinivaara et ai. 1966, and the fatty acid analyses in accordance with the methods used in the previous study (Varesmaa et al. 1968).

Stability of Whole, Filleted, and Minced Trout (Salmo Irideus Gibb) During Frozen Storage

“…The reports published by different authors show a strong disagreement about the practical storage life of frozen trout (Varesmaa et al 1969;Kuuppo et al 1978;Mills 1978); moreover, there is a scarcity of information on the storage of trout larger than the size of individual ration, which is considered to range from 150 to 300 g. For these reasons? we have investigated the stability of trout subjected to various types of commercial processing (whole fish, filleting and mincing) to determine the maximum keeping time in frozen storage.…”

STABILITY OF FROZEN TROUT I. TREATED AND UNTREATED MINCES STORED AT -12, -18, and -24 °C

“…No rancidity or changes in the overall flavour were detectable in the sensory taste analyses effected over the storage period. Various authors (Fukuda et al 1981, Kuuppo et al 1978, Varesmaa et al 1969 have reported the onset of rancidity to occur in less than five months in trout processed and packaged in a variety of ways. However, rancidity was not detected by sensory methods in any of the lots in the present experiment, probably due to the different source from which the trout were obtained or due to the vacuum-packaging.…”

Stability of Frozen Trout Ii. Different Trout Preparations Stored at -18°c

“…Oxidative rancidity is the primary factor limiting the storage life of frozen trout (Varesmaa et al 1969, Kuuppo et al 1978, Mills 1978, Wittig de Penna et al 1981, Borderias et al 1982 and has been found to occur in under five months at temperatures of around -2OOC. This paper presents a study of the most appropriate food processing techniques for achieving optimum utilization of all trout body parts.…”