Production of Trimethylamine in Frozen Cod Muscle

1968 ◽  
Vol 25 (5) ◽  
pp. 921-933 ◽  
Author(s):  
C. H. Castell ◽  
D. M. Bishop ◽  
Wanda E. Neal
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Storage Temperature ◽  
Bacterial Activity ◽  
Chemical Changes ◽  
Extractable Protein

Trimethylamine (TMA) was produced in frozen cod fillets and in scallop muscle under conditions where bacterial activity could not take place. The amounts formed were smaller than those which usually accompany bacterial deterioration of unfrozen fish. Decreases in storage temperature between −3 and −26 C reduced the rate of TMA formation. At −26 C no measurable increase of TMA was produced in cod fillets during storage periods up to 700 days.TMA formation appeared to be related to other chemical changes taking place in the frozen muscle. It followed shortly after the formation of free fatty acids and was almost simultaneous with changes taking place in the amounts of extractable protein.

Effect of Double Freezing and Subsequent Long-Term Refrozen Storage at −23 °C on the Quality of Inshore Male Capelin (Mallotus villosus)

1978 ◽  
Vol 35 (4) ◽  
pp. 452-456 ◽  
Author(s):  
J. R. Botta ◽  
D. H. Shaw
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Peroxide Value ◽  
Storage Time ◽  
Mallotus Villosus ◽  
Protein Nitrogen ◽  
Capelin Mallotus Villosus ◽  
Extractable Protein

Whole inshore male capelin (Mallotus villosus) were stored at −23 °C for 2 mo (C2), or 6 mo (C6) prior to thawing, beheading and eviscerating, and refreezing. Though the quality of the twice-frozen product was in both cases inferior to a once-frozen sample, it was still quite acceptable after 2 yr of refrozen storage. As expected, quality was superior in the C2 samples, but in both sets of samples taste deteriorated to a greater extent than texture. Chemical measurement of peroxide value indicated a possible development of rancidity that could not be detected by sensory analysis. Considerable lipid hydrolysis occurred, with the free fatty acids (FFA) at least doubling during storage; increases were greater in C6. In both experiments FFA production correlated with texture, taste, and with extractable protein nitrogen (EPN). Dimethylamine (DMA), trimethylamine (TMA), hypoxanthine, and EPN appeared to be good indicators of storage time and sensory quality. Key words: capelin, dimethylamine (DMA), extractable protein nitrogen (EPN), free fatty acids (FFA), hypoxanthine, peroxide value, refrozen storage, taste, texture, trimethylamine

Chemical Alterations in Fish Tissue During Storage at Low Temperatures

1969 ◽  
Vol 52 (5) ◽  
pp. 904-910 ◽  
Author(s):  
Garnett Wood ◽  
Lane Hintz ◽  
Harold Salwin
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Low Temperatures ◽  
Unsaturated Fatty Acids ◽  
Storage Temperature ◽  
Neutral Lipids ◽  
Fish Tissue ◽  
Protective Mechanism ◽  
Polyunsaturated Acids

Abstract Chemical changes that occur in the proteins, nucleotides, and lipids of fish tissue during storage at low temperatures were investigated. Homogenized tissue, prepared from fresh rock-fish (striped hass, Roccus species), was stored up to six days at temperatures from -10° to 4°C and then analyzed. At 0°C and below, the solubility of myofibrillar proteins decreased. There were also changes in polyacrylamide gel electrophoretic patterns of protein extracts. The total nucleotide content decreased rapidly at all temperatures. The lipids were extracted from each sample and separated into neutral lipids, phospholipids, and free fatty acids by column chromatography. The fatty acid composition of each fraction was determined by gas chromatography. In the fresh tissue, polyunsaturated acids occurred in greatest proportion in the free fatty acid and phospholipid fractions, whereas inono-unsaturated acids were inofe highly concentrated in the neutral lipids. The percentages of saturated acids were approximately the same in all fractions. During storage, there were considerably larger losses of individual acids from phospholipids than from neutral lipids. The polyunsaturated acids of the phospholipid fraction were affected most. Over 10% of these aeids were lost in six days at ice temperature, but only a small proportion of the losses was accounted for by increases in free fatty acids. Oxidative proo esses may account for the imbalance because the rate of oxidation, as measured by the thio-barbituric acid test, increased with storage temperature in the same manner as the rale at which unsaturated fatty acids were lost from the pliospliolipuls. Losses of polyunsaturated acids from the neutral lipids were much smaller, suggesting a selectively protective mechanism or environment in that fraction. The changes in the phospholipid fatty acids may provide the basis for useful objective tests of fish lecomposilion.

Effect of Stage of Rigor and of Freezing–Thawing Processes On Storage Quality of Refrozen Cod

1968 ◽  
Vol 25 (2) ◽  
pp. 299-320 ◽  
Author(s):  
J. A. Peters ◽  
J. W. Slavin ◽  
J. P. Lane ◽  
W. A. MacCallum ◽  
E. J. Laishley ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Frozen Storage ◽  
Taste Panel ◽  
Rigor Mortis ◽  
Protein Nitrogen ◽  
Circulating Water ◽  
Before And After ◽  
Extractable Protein

Trawler-caught cod were frozen before and after rigor mortis in brine (23% NaCI) and between refrigerated plates, thawed in circulating water at 7 C or in a conveyorized microwave oven, then processed into fillets which were packaged, plate-frozen, and stored at −18 C.All samples thawed satisfactorily in circulating water. Some overheating was encountered during thawing in microwaves. But the equipment was not developed sufficiently to permit assessment of the commercial potential of microwave thawing.Examinations of the fillets from the thawed fish for appearance, odor, and texture showed that freezing pre-rigor is preferable to freezing post-rigor and that thawing by means of microwaves is preferable to thawing by means of water. Freezing or thawing methods did not affect the pH of the thawed fillets.Results of organoleptic and chemical tests to determine the changes in quality of the refrozen fillets packaged and stored at −18 C for 12 months indicated that neither the average taste panel scores nor the chemical tests for moisture, total lipid, free fatty acids, and extractable protein nitrogen showed any difference attributable to state of rigor, freezing method, or thawing method. The taste panel slightly preferred the texture of fillets from fish frozen pre-rigor and from fish frozen in brine. Free fatty acids increased sharply as a result of thawing and refreezing, and the rapid increase continued during the first 2 months of frozen storage. Taste panel scores correlated significantly with free fatty acids (1% level) and with extractable protein (5% level).

scholarly journals The Effect of Lipolytic Enzymes of Bacillus spp. on Quality of Ultra-High-Temperature-Treated Milk

2006 ◽  
Vol 75 (3) ◽  
pp. 427-435 ◽  
Author(s):  
B. Janštová ◽  
L. Vorlová ◽  
M. Dračková
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Storage Temperature ◽  
Lipolytic Activity ◽  
Storage Period ◽  
Raw Milk ◽  
Model Case ◽  
Number Of Microorganisms ◽  
Bacillus Spp ◽  
Initial Content

Lipolysis was monitored based on determining the concentration of free fatty acids in milk, on the model case of UHT milk contamination with spores of 15 B. licheniformis, B. subtilis and B. cereus strains isolated from farm environment and raw milk. Lipolysis was not recorded at storage temperature of 4 °C, whereas significant changes in levels of free fatty acids were shown at storage temperature of 24 °C. After 3 weeks of storage the initial content of 41.97 mmol·kg-1 of fat rose to as much as 1,617.22 mmol·kg-1 of fat. The extent of the change depended mainly on the Bacillus spp. species and the storage period and, to a certain degree, also on the initial number of microorganisms. Significant lipolytic activity was detected in association with B. licheniformis and B. cereus species. It was found that spores of resistant B. licheniformis strains may survive 100 °C/10 min and 135 °C/5 s heating and show lipolytic activity.

scholarly journals Effects of lipolytic enzymes Pseudomonas fluorescens on liberation of fatty acids from milk fat

2000 ◽  
Vol 18 (No. 5) ◽  
pp. 175-182 ◽  
Author(s):  
M. Vyletělová ◽  
J. Ficnar ◽  
O. Hanuš
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Pseudomonas Fluorescens ◽  
Milk Fat ◽  
Storage Temperature ◽  
Raw Milk ◽  
Lipolytic Enzymes ◽  
Pasteurized Milk ◽  
Milk Samples

Effects of thermostable lipolytic enzymes Pseudomonas fluorescens 66 ZB in pasteurized milk on concentration of free fatty acids (VMK) in milk were studied in selected milk samples. Identical bulk milk samples were analysed by the method specified in previous papers (Vyletělová et al. 1999a, b, 2000). Reference milk samples (without bacterial strains) and the experimental ones (containing Ps. fl. 150 th. CFU/ml and 2800 th. CFU/ml, resp.) were stored at 6.5°C and 14°C and analysed at regular time intervals (24 h) – Table 1. An extractive-titric method (Kadlec et al. 1996; Table 2 and Fig. 2) was used for monitoring of fatty acid (MK) liberation. Precise analyses of MK and VMK were made by the chromatographic method (Figs. 1, 3 and 4). Medium-chain fatty acids (C12–C16) are liberated first of all; short-chain acids (C6–C10) were found sporadically or in very small quantities (Table 2). Dissociation constant of the specific fatty acid liberated from milk fat affects principally relationships between pH and free fatty acid concentration. The predominating proportion of long-chain acids in liberated fatty acid formation is associated with lower reduction of pH as compared to the predomination of fatty acids with shorter chains associated with more substantial reduction of pH. In our study, a rapid decrease of pH was noted before 168 h (Table 24); this corresponds to low concentrations of short-chain free fatty acids. Vyletělová et al. (2000) found significant relations between pH and contents of VMK (measured by the extractive-titric method); in some samples, correlation coefficients amounted to r = –0.93*** (P £ 0.001). The extractive-titric method analysing VMK concentrations (mmol/kg milk fat) provides results characterized by a systematic rise (e.g., 32.0 mmol/kg instead of 13.0 mmol/kg in raw milk). According to Kratochvíl (1992) 20 mmol VMK/kg milk fat signalized the starting point characterizing flavour degradation of milk caused by activities of fatty acids C12–C14 above all; the transformed value (respecting specifics of the extractive-titric method) amounts to 49 mmol/kg. In case of higher storage temperature a significant break is found after 144 h; in case of lower temperature this break is after 192 h (Table 2). Limits determining potential lipolytic modifications of milk flavour (RLZCHV) as related to specific samples and temperatures at VMK levels amounting to 49 mmol/kg or 20 mmol/kg are outlined in Fig. 2. Milk samples No. 5 and No. 6 stored at higher temperature surpassed this risk limit at 56 h and 64 h, respectively (Table 2, Fig. 2). On the contrary, milk samples stored temperatures corresponding to the standard storage temperature (storage of raw milk, transport, storage of pasteurized milk) surpass the mentioned risk level after 90 h and 140.5 h. Obtained results document the predominant role of storage temperature in the whole complex (production and processing of milk as a raw material or an intermediate product); evident differences in contamination rates (105 an 106) can be characterized as secondary effects in this case (Table 2). As related to practical conditions, the mentioned facts imply immediate processing of raw milk and pasteurized milk. This postulate must be respected namely by dairy plants producing delicate milk products. Vyletělová et al. (2000) found a notable VMK increase/24 h (7–11 mmol/kg milk fat) under specific temperatures and microbial contamination.

scholarly journals Lipoxygenase Activity of Hypodermal- and Middle-mesocarp Tissues from Netted Muskmelon Fruit During Maturation and Storage

1990 ◽  
Vol 115 (4) ◽  
pp. 612-615 ◽  
Author(s):  
Gene Lester
Keyword(s):  
Fatty Acids ◽  
Plasma Membrane ◽  
Free Fatty Acids ◽  
Phosphate Buffer ◽  
Cucumis Melo ◽  
Storage Temperature ◽  
Membrane Integrity ◽  
Lipoxygenase Activity ◽  
Plasma Membrane Integrity ◽  
And Storage

Lipoxygenase (LOX) activity was assayed on hypodermal- and middle-mesocarp tissues from netted muskmelon (Cucumis melo L.) fruit 10, 20, 30, and 40 days postanthesis and after 12 days of storage at 4 or 21C. Highest LOX activity was obtained using a phosphate buffer at pH 7 and 20C. LOX activity was detected only in hypodermal-mesocarp (hypodermic) tissue at 30 days postanthesis, and activity increased with fruit age and storage temperature. Antioxidants, which inhibit LOX, were detected only in hypodermic tissue from 10 through 30 days postanthesis fruits. Linoleic plus linolenic free fatty acids, substrates for LOX, in hypodermic tissue had declined at 30 days postanthesis, as did plasma membrane integrity, and both continued to decline in association with increased LOX activity.

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