Fish, peroxide value

FD. see Field desorption Fermentation, beer, 95 Ferrous oxidation/xylenol orange (FOX) method, lipid peroxide value (PV) basic protocol, 520-522, 526 characteristics of, 515, 526 modified, 527-528 FID. see Flame ionization detection Filtration, starch isolation, 676 Fish muscle, water retention examples, 320-323 (figs.) methods, 315-323... 

Fish sausages, terrines, and puddings elaborated with this treatment are commercialized in the Japanese market (Cheftel, 1995). When codfish meat was treated at 202,404 and 608 MPa during 15 to 30 min, the peroxide value of the oils extracted increased as pressure and time increased. However, when lipids extracted from fishes (sardine) and when defatted muscle is absent, the oxidation is minimum. This suggests that HP catalyzes the oxidation of lipids in fish muscles (Cheah and Ledward, 1995). 

Lipid oxidation during frozen storage of fat and medium-fat fish is an important quality problem, primarily due to effects on sensory properties such as rancid off-odor (appearing earlier than off-flavor), orange-brown discoloration, and texture changes. Changes in peroxide value (PV) and carbonyl compounds such as anisidine value (AsV), benzidine value, carbonyl value, and thiobarbituric acid (TEA) proceed... 

Kofakowska, A. and Szybowicz, Z., 1981a, An attempt to fix criteria of rancidity of frozen fish on a basis of colorimetric determination of peroxide value, Chlodnictwo, 16(7IS), 37, (in Pohsh). 

Analytical characteristics of fish oils and whale oils, 134,139 Analytical methods anisidine value, 264 AOCS, 259 dilatation, 253 fat adulteration, 270 fat content, 250 free fatty acids, 260 gas chromatography, 265 hydroxyl value, 261 iodine value, 259 lUPAC, 249 NMR spectra, 250 pancreatic lipase hydrolysis, 267 peroxide value, 263 phosphorus estimation, 264 saponification value, 260 slip point, 251 solid fat, 255 standard, 250... 

Sensory evaluation is a specialized discipline, using trained panels to measure and analyse the characteristics of food lipids evoked by the senses of taste, smell, sight and mouth feel. Sensory analyses are those most closely associated with the quality of food lipids, but their usefiilness is limited because they are costly and require a well-trained taste and odor panel and the proper facilities. However, sensory analyses provide sometimes ausefiil approach to identifying flavor or odor defects in the processing of food lipids that caimot be detected by other more objective chemical or instrumental analyses. For example, certain flavor defects characterized as grassy or fishy in linolenate-containing oils such as soybean and low-erucic rapeseed (canola) oils (Chapter 1) occur at such low levels of oxidation that they can only be detected by sensory analyses. The old term flavor reversion for soybean oil is based on the characteristic of this oil undergoing flavor deterioration at unusually low levels of oxidation that cannot be measured by peroxide value determination. Oils derived from fish... 

The volatiles derived from oils containing hnolenic acid (soybean and canola oils) have significant sensory impact and lower threshold values than the volatiles derived from oils containing linoleic acid (cottonseed, com and sunflower oils) (Table 5.1). The most sensory-significant linolenate-derived aldehydes (with lower threshold values) were characteristic in having n-3 unsaturation. These trends explain why linolenic acid oils develop undesirable odors and flavors at much lower levels of oxidation (peroxide value of less than 1) than linoleic acid oils (peroxide value of 10). Similarly, potent volatile aldehydes have been identified in fish oil oxidized at very low levels of oxidation by static and dynamic headspace GC (see F.2) and detected by GC-MS at parts per billion levels, including cw-4-heptenal (1250 ppb), fran, cw-2,6-nonadienal (1231 ppb)andCiXcw-3,6-nonadienal(627 ppb). Cis-4-heptenal is produced by decomposition of fran, cw-2,6-nonadienal, which can be produced in turn by the decomposition of n-7 and n-9 hydroperoxides derived from the oxidation of 20 4, 20 5 and 22 6 n-3 PUFA (Chapter 4, D4). 

Milk emulsions enriched with 1.5% fish oil were evaluated after cold storage at 2°C. Although the cod liver oil contained less n-3 PUFA (26%) than the tuna oil (38%), the milk enriched with cod liver oil that had an initial peroxide value of 1.5 oxidized much faster than the same milk enriched with tuna oil that had... 

Fish oils EDTA (ppm) Peroxide values (meq/kg) % Inhibition by EDTA Fishy odor Fishy flavor... 

Kummerow et al. (1948) found that the feeding of highly unsaturated fatty acids was detrimental to fat stability of eviscerated frozen turkeys, as determined both by peroxide values on the extracted skin fat and also by organoleptic tests on the cooked carcass. Klose et al. (1951) observed fishy flavors in roasted turkeys fed linseed oil as well as fish oils. The fishy flavors in this case were present in the fresh roasted turkeys as well as in those cooked after being stored in the freezer. Peroxide values of birds fed linseed oil increased very rapidly in freezer storage. 

Stansby, M. E. 1941. Determination of peroxide values for rancidity of fish oils. Ind. Eng. Chem., Anal. Ed. IS, 627. 

Highly refined and stabilized (with antioxidants) fish oils, to remove off-flavors, inhibit oxidation, and extend shelf life, have been successfully incorporated into products such as low-fat spreads (containing about 1 %-2% EPA/DHA) and bread (0.2%-0.5% EPA/DHA) (Madsen, 1998 Newton and Snyder, 1997). Antioxidants such as vitamin E may also be added into the spread (Hilliam, 1996). A low-fat spread into which a stabilized fish oil had been incorporated at a level of 3% (0.8% EPA/DHA) could be stored for up to 3 months without changes in stability parameters (e.g., peroxide value, sensory quality) (Kolanowski et al., 2004). 

Feeding menhaden (fish) oil at 2% of the dry matter intake of the diet also lowered milk fat concentrations. The level of CL A was increased by approximately 3.6 fold, but there was also a concurrent 4-5 fold rise in the level of vaccenic acid. Increasing the oil intake to 3% had no additional effects. The level of n-3 fatty acids in the milk was increased, mainly due to increased levels of eicosapentaenoic acid (EPA 20 5n-3), as was the level of total trans monoenes. The effects of pasteurization and oxidation on the raw milk were examined but no significant changes were observed and the CLA isomer profile was unchanged. There were no significant flavour differences found between the milk (and butter made from the milk) of cows fed 2% menhaden oil and control samples. The higher polyunsaturated fat content of the butter meant that it was softer at 4°C and 20°C, but the acid value and peroxide value of the butter were similar to those of control samples even after 3 months. A consumer evaluation of milk from cows fed a fish oil diet found no difference in acceptability compared with the control milk (Ramaswamy et al, 2001). 

Han et al. [48] also studied the effects of various antioxidants such as ascorbic acid, a-tocopherol, and rosemary extract on the oxidation of fish oil and soybean oil using phosphatidylcholine reverse micelles. Peroxide values of the oils indicated that only ascorbic acid (0.02%) solubilized in the reverse micelles was an effective antioxidant in both fish oil and soybean oil. Also, as in the other studies, a combination of ascorbic acid and a-tocopherol was shown to act synergistically in the fish oil. 

The Arrhenius parameters of the isomerization reactions have not been directly measured experimentally, but their relative activation energies have been estimated. Table 3 shows the values of the activation energy and rate coefficient at 600 °K estimated by Fish [58] for isomerizations involving H-transfer from primary, secondary and tertisiry atoms in the a, 3, 7 and 5 positions to the peroxidized C-atom, viz. 

Fig. 3. Maximum light emission of the ventral zone induced by hydrogen peroxide in relation to the size of the sharks. Dashed line separates embryos from free-swimming fish. Values are expressed as mean SEM.

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