The loss of water- and lipid-soluble antioxidants of mackerel light and dark muscle was determined as a function of time of storage on ice to provide clues as to mechanisms of oxidation and to assess the use of antioxidants to measure and predict quality. Glutathione and ascorbate decreased faster initially than α-tocopherol and ubiquinone in both light and dark muscle of mackerel; in dark muscle, the rate of loss of ubiquinol was comparable to the loss of the water-soluble antioxidants. Antioxidants decreased more rapidly initially in dark muscle than in light muscle. Rates of sensory quality loss in the light and dark muscles were similar except that initial loss of quality in the dark muscle was greater than that in the light. Regression equations showed good relationships of tocopherol, ubiquinone-10, and TBARS in light and dark muscle with storage time. Ascorbate and glutathione gave the best correlation values with sensory scores for light muscle, while a good relationship was seen in dark muscle between sensory score and reduced or oxidized CoQ, ascorbate, and glutathione. The kinetic data suggest an important role of mitochondria in lipid oxidation in mackerel dark muscle. Keywords: Mackerel; antioxidants; ascorbate; glutathione; α-tocopherol; coenzyme Q; stability

The wide range of cholesterol values given in the literature for LO&J pealei and Illex iflecebrosus is confusing to people who arc designing low cholesterol diets for health purposes. These species were analyzed for proximate composition, fatty acid content, and cholesterol content in order to provide information to consumers and health care profcssionals. A sampling of both species of squid over a 2-yr period rcvealed that cholesterol values ranged from about 110 mg up to 450 mg/lOOg raw tissue with no apparent correlation with season or location of catch. The wide range of values, thercforc, seems to reflect natural occurences.Omega-3 fatty acids make up over 50% of the total fatty acids, but these squid, because they are low in fat (about lS%), contribute only about OSg of these fatty acids per IOOg in the diet.

The cholesterol value for several species of shrimp from several different geographical locations was determined. The overall average for all the samples was 152 rt 15 mg/lOOg of edible portion of shrimp. Two samples of Pundulus borealis, Gloucester prawns and Canadian prawns, accounted for the low (136 mg/lOOg) and the high (186 mgl 1OOg) limits, respectively, of the range of cholesterol. All shrimp were low in fat at about 1%. Eicosapentaenoic and docosahexaenoic acids were present at about 30% of the total fatty acids, providing about 0.2Og/lOOg in the edible portion. INTRODUCTIONTWO REPORTS issued by the National Heart, Lung and Blood Institute (1987) have reconfirmed that modification in dietary cholesterol intake can, in many individuals, reduce blood cholesterol. These reports have prompted health care professionals and consumers to search the literature for the information necessary to make dietary assessments.Definitive dietary fat information on shrimp is lacking in the literature. Considerable data spanning a wide range of values have been generated on the cholesterol content of shrimp. The information has been summarized in an extensive literature review of nutritional data through 1975 by Sidwell (1981) and for the years 1976-1984 in a literature review by Krzynowek and Murphy (1987). Exler (1987) and Dudek et al. (1982) report information on shrimp after various methods of cooking. For raw shrimp, the cholesterol values range from 80.7 mg/ 1OOg (Punwar and Derse, 1978) for an unspecified species of shrimp (not stated, but assumed raw) to a high of 226 mg/ 1OOg (Kritchevsky et al., 1967) for an unspecified species of, once again not stated, but assumed raw shrimp. A range of values, such as this, is not conducive to menu planning around a low cholesterol regime of 300 mg/day for a man and 225 mg/day for a woman.Concomitant with the decreased ingestion of cholesterol for health conscious individuals came the increased consumption of seafood for the .prevention and amelioration of certain diseases, more specifically cardiovascular diseases (Simopoulos et al., 1986;Lands, 1986;Kinsella, 1987;Nettleton, 1985Nettleton, , 1987. Seafood is the richest source of a'group of polyunsaturated fatty acids called omega-3 (o-3) fatty acids. The low incidence of cardiovascular disease among populations of people who consume large quantities of seafood has been attributed to this group of omega-3 fatty acids. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the most abundant of these omega-3 fatty acids.Several species of Pemeus shrimp and two geographically distinct samples of Pundulus borealis were analyzed for total cholesterol to provide cholesterol data for shrimp and to determine any species differences. Some of the samples were analyzed to ascertain their fatty acid contribution to the human diet.

Minced mackerel muscle was less stable at -20 °C than minced bluefish muscle as judged by odor evaluation but not by production of TBA-reactive substances. Minced mackerel muscle lost total glutathione faster than minced bluefish muscle at both -20 and 2 °C. Loss of glutathione was also more rapid in mackerel fillets than in bluefish fillets, but the differences were less. Sensory scores declined in both species after about two-thirds of the glutathione was lost. Neither soluble selenium nor glutathione peroxidase, oxidized glutathione reductase, or glutathione transferase activities appeared likely to account for the differences observed in glutathione losses. In a model system of washed, minced mackerel light muscle, glutathione/glutathione peroxidase was an effective antioxidant against lipid oxidation induced by an exogenous free radical-generating system. It seems possible that glutathione protected the fish muscle against quality loss in the early stages of storage.

A method for fish species identification by isoelectric focusing of sarcoplasmic proteins on LKB Ampholine PAGplates, pH 3.5–9.5, was collaboratively studied to determine whether photographs of protein patterns from authentic species could be used to identify unknown samples. Seven collaborators were sent 8 unknown samples in duplicate to identify from an 8 × 10 in. photograph of an Ampholine PAGplate showing standard protein patterns from 14 species of fish. The 7 collaborators identified the unknown samples with 93% accuracy. Eight of 14 monkfish samples were not identified correctly and showed protein patterns different from the protein patterns shown in the photographic standard. All of the incorrectly identified samples showed the same protein pattern. The other 7 unknown species were all correctly identified. The method has been adopted as official first action.