SEASONAL CHANGES IN PROXIMATE COMPOSITION OF ANCHOVY AND STORAGE STABILITY OF ANCHOVY OIL

Changes in proximate composition of anchovy were investigated during the catching season from October to March. In addition, stability of anchovy oil depending on storage temperature and time were studied. During the recent study, water, fat, protein and ash content of anchovy varied between 65.9–74.0%, 9.0–15.3%, 12.8–16.4% and 1.7–2.2%, respectively. The anchovy oil stored at 4C was found to be unacceptable for consumption at the end of the 90th day of storage according to peroxide, acid, unsaponifiable matter and thiobarbituric acid values. An identical sample stored at − 18C was acceptable for 120 days of storage, but eventually became unacceptable after that.

PRACTICAL APLICATIONS

Anchovy has a great economic importance for the Turkish fishery industry. Approximately 42% of the annual catch of anchovy is used in fish meal and oil production in Turkey ( SIS 2002 ). Therefore, the proximate composition of anchovy and seasonal changes have fundamental importance for consumers, manufacturers and wholesalers, because it is important for consumers to know what they eat, for manufacturers to figure out how they manage long storage stability for their products, and for wholesalers to buy equivalent of their payment. An important issue that has attracted attention of the manufacturers is the storage life of fish oil. Therefore, the results presented in this study are expected to be useful for the fish oil industry in Turkey or even in other countries processing anchovy into fish oil.     

CHANGES IN MYOFIBRILLAR PROTEINS AND LIPIDS OF SQUID (ILLEX ARGENTINUS) DURING FROZEN STORAGE

The biochemical properties of actomyosin (AM) and lipid composition of the mantle from frozen‐stored whole squid were investigated. Irrespective of the sex of specimens, during the first months of storage, there was a trend of decreased protein solubility, reduced viscosity and enzymatic activities of AM. A significant decrease (P < 0.05) in the relative percentage of the myosin heavy chain and a significant increase (P < 0.05) in those of paramyosin and the 155‐kDa component were also observed. After freezing, phospholipids (PL), sterols (ST) and triacylglycerols (TAG) represented 38.6, 29.1 and 21.2%, respectively, of total lipids (TL) from the mantle of male squid. Free fatty acids (FFA) plus diacylglycerols constituted only 11% of TL. TL extract from the mantle of female squid had a higher percentage of PL and had lower ST. In the frozen‐stored male and female squid, TAG were hydrolyzed earlier than PL. At zero time of storage, the relative percentages of saturated and unsaturated fatty acid in TL extracts from the mantle of male and female squid were 39.1, 59.2 and 38.7, 61.1, respectively. Irrespective of sex, the saturated FA fraction significantly (P < 0.05) decreased and the unsaturated one significantly (P < 0.05) increased after 8 months of frozen storage.     

CHANGES IN RESIN COMPOSITION AND BREWING BEHAVIOUR OF HOPS DURING STORAGE

Changes in resin components and brewing value of several varieties of hops stored at two temperatures have been examined. Different varieties and temperatures of storage gave rise to significant changes in resin and oil composition, but these variables had little effect on bittering capacity.     

PRODUCTION AND PROXIMATE COMPOSITION OF A HYDROPONIC SWEET POTATO FLOUR DURING EXTENDED STORAGE

In developing countries, where limited transport infrastructure exists, processing the sweet potato (Ipomoea batatas (L.) Lam) into flour provides an alternative to the difficulties associated with storage and transport of the raw roots. The objectives of this study were: (1) to process hydroponic sweet potato roots into flour; and (2) to evaluate the nutritive composition and the color of the processed hydroponic sweet potato flour during storage. The TU–82–155 hydroponic sweet potatoes were processed into flour and stored for five months at room and refrigerated temperatures. The sweet potato flour contained 3.0%, 4.5%, 1.0%, 1.0%, 90.6% moisture, ash, fat, protein, and carbohydrate, respectively, with no significant changes during storage. The *L values for the sweet potato flour increased as storage time increased, but the *a and *b values decreased. Hydroponic sweet potato roots could be processed into flour and stored at 4C or 21C to 25C for five months without deterioration in quality.     

PHYSICOCHEMICAL AND BIOCHEMICAL CHANGES IN WHOLE LIZARDFISH (SAURIDA MICROPECTORALIS) MUSCLES AND FILLETS DURING FROZEN STORAGE

The physicochemical and biochemical changes in whole lizardfish (Saurida micropectoralis) muscles and its fillets kept in air and under vacuum during frozen storage at ?20C for 24 weeks were investigated. The formaldehyde (FA) and dimethylamine contents increased with a concomitant decrease in trimethylamine‐ N‐oxide (TMAO) content as the storage time increased (P < 0.05). The Ca²⁺–adenosine 5′‐triphosphatase activity continuously decreased with a coincidental decrease in salt‐soluble fraction. The disulfide bonds were increasingly formed throughout the storage (P < 0.05). The surface hydrophobicity increased and reached the maximum at week 12 with a subsequent decrease up to the end of storage. In general, the higher changes were observed in samples kept under vacuum than those kept in air. With the same atmosphere used, the whole fish showed slightly higher changes than the fillets. A marked increase in TMAO demethylase (TMAOase) activities was observed up to 12 weeks, followed by the continuous decrease up to 24 weeks of storage. The produced FA might play an important role in inducing protein denaturation and/or aggregation in lizardfish. The TMAOase activity as well as the FA formation could be reduced to some extent with the removal of internal organs and storage in the presence of oxygen. However, a detrimental effect of oxygen, especially on the promotion of lipid oxidation, would be an obstacle.     

QUANTITATIVE CHANGES IN WHOLE MYOFIBRILS AND MYOFIBRILLAR PROTEINS DURING FROZEN STORAGE OF TRUE COD

The extractability of whole myofibrils from true cod decreased more rapidly during frozen storage at −40°C than did the extractability of the component myofibrillar proteins. There was a 95% decrease in extractable myofibrils after 6 months in storage, but only a 23% decrease in extractable myofibrillar proteins.     

QUALITY CHANGES OF BLUE CRAB (CALLINECTES SAPIDUS) MEAT DURING FROZEN STORAGE

The aim of the investigation was to determine the quality changes of blue crab (Callinectes sapidus) meat during frozen storage. Blue crabs were obtained directly from fishing boats in the Gulf of Antalya, Turkey and immediately transferred to the laboratory alive. Whole crabs were placed into polyethylene polyamide (PE/PA) pouches, shrunk and stored at ?18C for 10 months. The main changes that take place in blue crabmeat were investigated by means of sensory assessments (odor, appearance), chemical analyses (total volatile bases (TVB‐N), trimethylamine (TMA‐N)) and physical measurements (pH). TVB‐N, TMA‐N values and pH were significantly (P < 0.01) different following frozen storage. Moreover, it was observed that the differences in odor values were significant (P < 0.05), while appearance values were not. All of the measurements indicated that blue crabmeat kept its good quality at ?18C for 10 months.     

NUTRITIONAL ESTIMATION OF CHANGES IN MINERAL CONTENT DURING FROZEN STORAGE OF WHITE ASPARAGUS

Nine essential elements (copper, iron, zinc, manganese, calcium, magnesium, sodium potassium and phosphorous) were determined in white asparagus (Asparagus officinalis, L.) by flame atomic absorption spectrophotometry in order to examine the possible variations in mineral content caused by frozen storage at ?18C for 45 and 90 days. Statistically significant differences were determined during frozen storage for all the mineral elements investigated, except for Ca, Mg, Na and P which did not exhibit any significant differences (p>0.05) and, together with Zn, showed no significant modifications under frozen storage. A diminution in Cu, Fe, Mn and K concentrations was observed during the frozen storage time. Statistically significant differences were established between thicknesses of the asparagus spear in the content of Cu, Fe, Zn, Ca, Na and K and it was seen that the thickness of the asparagus did not fit any specific model. Between portions, all the elements studied displayed statistically significant differences in their concentrations, except for Ca and K (p>0.05) and, for all the minerals elements analyzed, the highest levels were found in the apical portion of the asparagus spear, except for Na with a higher content in the basal portion. White asparagus is an adequate food source of mineral elements, except for Na, and frozen storage does not cause any great variations in the percentages of mineral RDAs (Recommended Dietary Allowances) supplied.     

FROZEN STORAGE CHARACTERISTICS OF COWNOSE RAY (RHINOPTERA BONASUS)

Frozen-stored (-18°C) vacuum-packed portions ofcownose ray (Rhinoptera bonasus) flesh, periodically analyzed for quality by chemical tests for ammonia nitrogen, pH, peroxide value, TBA content, extractable protein nitrogen, and by sensory methods, were still acceptable after 60 weeks.     

EFFECTS OF CRYOPROTECTANTS IN MINIMIZING PHYSICOCHEMICAL CHANGES OF BOVINE NATURAL ACTOMYOSIN DURING FROZEN STORAGE1

Physicochemical changes in bovine natural actomyosin extracted from prerigor semimembranosus muscle were investigated during frozen storage at ?28°C as affected by the addition of cryoprotectants (5.6% Polydextrose® or 5.6% mixture (1:1) of sucrose and sorbitol). Proteins were destabilized during freezing and frozen storage as reflected by decreases in protein solubility, the visual appearance of aggregates in protein sols, decrease in intensity of flow birefringence, intrinsic viscosity and ATPase activity, and changes in size, shape, or charge of the protein (especially myosin) as evidenced by nondenaturing electrophoresis. These effects were reduced to some extent by the two cryoprotectant treatments.