Microbiological and Color Quality Changes of Channel Catfish Frame Mince During Chilled and Frozen Storage

Microbial counts and color values of channel catfish frame mince were determined during storage at -20, 0, and 5 °C. Aerobic plate counts increased from 5.5 to greater than 8 log10 CFU/g by 3 d at 0 and 5 °C. Total coliform counts increased 1 log during refrigerated storage for 5 d. Both microbial populations declined during 3 mo frozen storage. Washed mince was lighter in color, less red, and less yellow than unwashed mince. Color of both mince types did not change during storage. Microbial results suggested that prepared catfish frame mince should be stored no longer than 3 d at 0 to 5 °C. Frozen mince remained acceptable for at least 3 mo at 20 °C. Key Words: catfish, mince, quality, microorganisms, color     

Effect of NaCl, polydextrose, and storage conditions on the functional characteristics and microbial quality of pre- and post-rigor salted beef

The functionality and microbial storage life of pre-rigor beef mince stored at −1.5 °C under vacuum or a saturated carbon dioxide atmosphere, or at −18 °C in polyethylene bags, was investigated. Salt (2% w/w) or salt plus the cryoprotectant Polydextrose^® (2%/2.6% w/w) was added pre-rigor to some samples. Chilled storage decreased salt soluble protein (SSP) by 13–18% (P < 0.01); frozen storage decreased SSP content by 20%. Pre-rigor salted mince in saturated carbon dioxide packs had a satisfactory microbial quality after 12 weeks storage. The cook yield of finely comminuted sausage batters made from that mince and from fresh pre-rigor mince were similar, although batter stress and strain decreased with chilled storage. Adding Polydextrose^® to salted mince improved batter strain compared with the non-additive and salt-only samples and improved batter stress compared with the salt-only samples. The microbial storage life of chilled vacuumpacked unsalted mince was less than 6 weeks; pre-rigor salting increased its storage life.     

CHANGES IN PROXIMATE COMPOSITION OF THORNBACK RAY (RAJA CLAVATA, L. 1758) SURIMI DURING WASHING AND FROZEN STORAGE

The effects of frozen storage of surimi produced from thornback ray and the washing of mince on the chemical composition were investigated. The crude ash content which was initially found as 1.38% in raw thornback ray decreased approximately 12 and 80% after the first and second washing, respectively. After the third washing, crude ash content increased to 207% of the amount in the second washing because of addition of salt to the last washing water. The crude protein content of mince also decreased approximately to 28 and 20% after the first and second washing, respectively. After the third washing, the decrease in the lipid levels was approximately 30%. At the end of 6 months of frozen storage at − 23.8  ±  2C, dry matter, crude ash and crude protein contents increased in a greater ratio in surimi containing 4% sorbitol, 4% sucrose and 0.3% Na-tripolyphosphate than surimi prepared with 8% sorbitol and 0.3% Na-tripolyphosphate.

PRACTICAL APPLICATIONS

In the present study, the effects of frozen storage of surimi produced from thornback ray and the washing of mince on the chemical composition were investigated. Washing procedure significantly decreased crude ash, crude protein and crude fat content of mince. There were significant differences in moisture, crude ash, and crude protein contents during the 6 months storage period of frozen surimi obtained by using different cryoprotectant mixtures. The folding test scores were highest in fresh surimi and during the first two months of storage. Thornback ray can be used for the production of surimi.     

Effect of muscle condition before freezing and simulated chemical changes during frozen storage on protein functionality in beef

The effect of rigor temperature (RT, 35 versus 10°C), increased ionic concentration (MS: 0 versus 0·2% mixed salts), oxidized lipids (OL, 0 versus 1% added oxidized fat), increased free amino acids (FAA, 0 versus 0·3% added mixture of amino acids), fat content (FC, 0 versus 15% added fat) and excluding atmospheric gases (V, 0 versus 99·9% vacuum) on protein functionality in mince stored 1 month at -20°C was studied using a complete 2(6) factorial design. All factors studied affected the functional properties of beef. Fresh 24hr samples that entered rigor at 35°C had lower total (TPS), myofibrillar (MPS) and sarcoplasmic (SPS) protein solubilities than samples entering rigor at 10°C (p<0·01). During frozen storage, RT, MS and OL alone did not affect protein solubilities, FAA increased TPS but did not affect MPS and SPS, increasing the meat's fat content raised TPS and SPS but did not affect MPS, applying a vacuum increased TPS and MPS but lowered SPS (p<0·05). Cook yield of frozen stored mince increased with higher FAA but decreased with higher fat content, and the peak force of patties made from frozen stored mince was lowered by increased MS and low FC during storage. Various significant interactions are tabulated and discussed.     

不同贮藏温度对速冻羊肉品质影响的实验研究

为研究时间对不同贮藏温度下速冻羊肉品质的影响,采用了菌落总数、挥发性盐基氮、pH、酸价及水分含量为指标,对速冻羊肉在-15、-20、-25℃三种不同温度冻藏温度和5、15、25℃三种不同冷藏温度下中的上述指标的变化进行了研究。实验结果显示,菌落总数、挥发性盐基氮、pH、酸价随贮藏时间的延长而增加,随贮藏温度的增加而上升。与冷藏温度下贮藏的速冻羊肉相比,冻藏能更好保持速冻羊肉的品质,减缓细菌的生长,减少水分的散失,能更久地保持其品质与延长其货架期。     

Changes in lipids,proteins and kamaboko forming ability of silver carp (Hypophthalmichthys molitrix) mince during frozen storage

Frozen storage of mechanically deboned silver carp (Hypophthalmichthys molitrix) mince for 180 days resulted in a significant (P⩽0.05) decrease in myofibrillar proteins. In contrast, peroxide value (PV), free fatty acids (FFA) and total volatile base nitrogen (TVBN) contents increased significantly (P⩽ 0.05) throughout the storage period. The kamaboko forming ability and the sensory scores of the silver carp mince decreased significantly (P⩽0.05) during the storage period. Texture of the mince was significantly (P ⩽ 0.001) correlated with the decrease in the myofibrillar proteins (salt-soluble proteins), jelly strength and folding test grades; and increase in expressible water percentage, PV, FFA and TVBN content. Based on ‘texture’ of the mince, the product was acceptable for 180 days at −18°C.     

Chemical and sensory quality changes of fish fingers,made from mirror carp (Cyprinus carpio L., 1758), during frozen storage (−18 °C)

The effects of frozen storage at −18 °C on the chemical and sensory qualities of fish fingers produced from unwashed and washed mirror carp (Cyprinus carpio) mince were investigated. The amounts of moisture, crude protein, lipid, crude ash, ω3 polyunsaturated fatty acids (PUFA ω3), and ω6 polyunsaturated fatty acids (PUFA ω6) in fish fingers produced from unwashed mince (UWF) were found to be 68.50%, 15.5%, 6.00%, 2.20% 2.31%, and 55.2%, respectively, while they were found to be 70.23%, 10.8%, 2.14%, 1.80%, 2.28%, and 54.6%, respectively, in carp fingers produced from washed mince (WF). The thiobarbituric acid value (TBA, mg malonaldehyde/kg) was found to be significantly higher in mince of WF than in mince of UWF and increased significantly during frozen storage in both the mince of UWF and WF (p < 0.05). A significant decrease in pH was obtained throughout the washing treatment (p < 0.05). There were no significant differences of pH in either the mince of UWF or WF between the beginning and end of the storage periods (p > 0.05), whereas a sharp increase was observed in the fourth month in both groups. The protein solubilities of the mince of both UWF and WF decreased significantly throughout the storage periods (p < 0.05). Sensory parameters of colour, odour, flavour, and general acceptability for both groups decreased during the frozen storage period (p < 0.05) but were still within acceptable limits. It was also concluded that mirror carp was a good source for fish fingers and that product could be stored for five months in a frozen state without undesirable changes of sensory and chemical qualities.     

Effect of packaging and frozen storage temperature on beef pigments

The influence of final freezing and storage temperature on pigment modifications of beef samples wrapped in polyethylene and EVA/SARAN/EVA was analysed. Met-, oxy- and myoglobin relative surface concentrations were determined using reflectance spectrophotometry. Pigment behaviour during storage of beef packaged in both films and oxygenation of vacuum-packaged samples was described by different reaction schemes and modelled to obtain kinetic and equilibrium constants. Comparative studies performed with beef samples (a) refrigerated, (b) frozen to –5°C and stored at this temperature (partial freezing), and (c) frozen to -25°C and stored at -5 and -20°C, indicated that for aerobic storage periods of 90 days, metmyoglobin levels of partially frozen samples upon thawing were comparable to those of frozen samples stored at –20°C. For vacuum-packaged beef, pigment concentrations remained practically constant during frozen storage; partial freezing increased oxygenation capacity of the tissue compared with chilled and frozen conditions.     

Effect of Calcium Salts on the Properties of Proteins from Oil Sardine (Sardinella longiceps) During Frozen Storage

ABSTRACT:  The effect of calcium sulfate and calcium chloride on the enzymatic and structural properties of actomyosin isolated from sardine was investigated. Mince was prepared from sardine and different concentrations of calcium chloride and calcium sulfate were added to the mince and kept in frozen condition at −20 °C. The physico-chemical and functional properties of proteins from mince were analyzed as a function of time. The solubility of proteins decreased during storage. The reduction in solubility was less for samples treated with calcium chloride. However, sardine mince showed better functionality during storage in the presence of calcium compounds. The ATPase enzyme activity of actomyosin increased with increase in concentration of calcium and decreased after reaching the maximum value. ATPase activity of proteins from mince decreased during storage at low temperature. The reduction in ATPase activity did not correlate with the loss of functionality of proteins. SDS-PAGE did not reveal any major changes in the protein profile during storage as well as in the presence of different concentration of calcium compounds. The secondary structural content of actomyosin was not altered in the presence of both calcium chloride and calcium sulfate as evident from circular dichroic measurements.     

EFFECTS OF ADDITIVES ON QUALITY OF MECHANICALLY EXTRACTED JONAH CRAB (CANCER BOREALIS) MINCE DURING REFRIGERATED STORAGE1

Research was conducted to determine yield and composition of mechanically separated Jonah crab mince prepared from processing discards and to evaluate effects of different additives on the chemical and microbiological quality of the mince. The following additives were used: 2% or 5% dried rosemary (with or without 2% lactic acid), 400 ppm and 800 ppm diacetyl (with or without 2% lactic acid), 2% sodium lactate, and a control (with or without 2% lactic acid). The eleven treatments were stored at 5C for 8 days, and periodically subjected to total volatile base nitrogen (TVBN), pH, thiobarbituric acid (TBA), and microbial analyses. Lactic acid, 400 ppm and 880 ppm diacetyl, and sodium lactate were effective in inhibiting TVBN and TBA production. Sodium lactate, 5% rosemary and 800 ppm diacetyl had the highest antimicrobial activity. Combinations of additives are recommended to improve different aspects of crab mince quality during refrigerated storage.