Phosphate treatment of frozen prawns. Pt. 1. Screening of various phosphates for prevention of drip loss

Various phosphates and their mixtures were screened for their efficiency of preventing drip loss in frozen prawns. The effectiveness of the phosphates decreased in the following order: Sodium tripolyphosphate — Sodium pyrophosphate — Sodium hexametaphosphate Sodium metaphosphate — Sodium dihydrogen phosphate; the last two being ineffective. Even though thaw drip loss was reduced by the above treatments the organoleptic quality of the thawed as well as cooked products was unsatisfactory, discoloration being the major defect. A solution of a mixture of 12% sodium tripolyphosphate and 8.6% sodium dihydrogen phosphate or 2% citric acid in water when used as dip prevented thaw drip loss, improved cooked yield and organoleptic quality without adversely affecting the biochemical characteristics. Commercial scale trials showed that the results are highly reproducible.

Studies on technological problems associated with the processing of cooked frozen prawns. Pt. 1. Preprocess storage conditions of raw material in relation to quality

The chemical and organoleptic properties of prawn held in ice for different days prior to cooking and the changes after freezing and subsequent storage were studied with three different species of prawn viz. Metapenaeus monoceros, Metapenaeus dobsoni and Parapeneopsis stylifera. The optimum period for which the prawn can be kept under ideal conditions of icing prior to cooking has been worked out.

An effective method for reducing belly-bursting in frozen oil sardines

A dip treatment in 15% sodium chloride solution for 30 minutes prior to freezing was found to be effective in reducing belly-bursting occurring during freezing and thawing of oil sardines. The effect of size and fat content of sardines on belly-bursting phenomenon and storage characteristics of brine treated sardines have been studied.

Studies on technological problems associated with the processing of cooked frozen prawns. Pt. 2. Hygienic conditions in relation to bacteriological characteristics

The importance of sanitary practices in the processing of precooked frozen shrimps has been discussed. Several typical examples have been shown to point out the different sources of contamination of the product and the extent to which each of the factors by itself or in combination affect the bacterial quality of the final product. A scheme of processing has also been suggested for controlling the microbial quality.

Experiments in constituting a taste panel for canned and frozen prawn products

With a view to constituting a taste panel in the laboratory for detecting the flavor changes in canned and frozen prawn, three methods of panel selection (scalar scoring method, range and deviation method and triangular method) were tried. Out of the three, triangular method was found to be suitable for panel formation in canned and frozen prawn. Using this method a panel of six members was formed for detecting flavor changes in the two products.

Preservation of fish by freezing and glazing. Pt. 1. Bacteriology of fresh, frozen and glazed fish

Microbiological investigation of fresh and frozen fishes such as pomfret, surmai and mackerel was carried out under various conditions of preservation. Glazing, block-freezing and preservation in gunny bag were affected. Determination of bacterial load and isolation, identification and classification of the resistant bacteria were made. Spore-formers of Subtilis mesentericus group were found to be resistant to freezing as well as glazing by ascorbic acid, citric acid and sodium nitrite except a mixture of sodium chloride and glucose. Bacterial load was reduced to a good extent and maintained low till the end of frozen storage period.

Preservation of fish by freezing and glazing. Pt. 3. Effect of freezing, glazing and frozen storage on the B-vitamins and essential minerals present in the fish flesh

The changes occurring in moisture, thiamine, riboflavin niacin, phosphorus, iron and calcium in pomfret, surmai and frozen mackerel, glazed with ascorbic acid, citric acid, sodium chloride, glucose, sodium nitrite and kept under frozen storage were studied up to 6 months and results reported.

Standardization and frozen storage of fish cutlet from bleached and unbleached mackerel mincemeat

In the present study, fish cutlets were prepared from bleached and unbleached mackerel mincemeat. Fish cutlets prepared from bleached meat had scored higher values for taste, flavour and overall acceptability as compared to those from unbleached mincemeat. Fish cutlets prepared with corn flour at the rate of 15% of fish mincemeat had scored higher values for all attributes as compared to other levels. Between the bleached and unbleached mincemeat, the scores for cutlet prepared with bleached mincemeat had higher score than that for the latter. There were no cracks in cutlets prepared with 15% and above corn flour levels as compared to those with lower levels. Fish cutlets prepared from bleached and unbleached mincemeat with spice mixture at 20 and 30% of the fish mince, respectively, had higher scores for taste, flavour, texture and overall acceptability as compared to those with other levels. Organoleptic quality of cutlet prepared from bleached and unbleached mackerel mince did not show changes in the appearance, colour and texture during storage. Changes were more prominent in flavour, taste and overall acceptability. Fish cutlets prepared from bleached mincemeat were acceptable for two months and those from unbleached mincemeat were acceptable up to one month from the point of view of organoleptic and biochemical qualities.

Survival of Staphylococci on frozen fish

Using Staphylococcus aureus as the test culture it has been shown that cell injury occurs in two phases during freezing and storage at temperatures below freezing. Certain constituents of fish muscle appear to protect the cells during both phases of injury. The survival of bacteria on fish muscle is not influenced by the rate at which the fish muscle was frozen prior to inoculation. There was no significant difference between growth of bacteria on quick frozen and slow frozen fish muscle after thawing. However there appeared to be a slight tendency for the lag phase of growth to be extended on thawed quick frozen fish muscle when compared with thawed slow frozen muscle.

Growth of the buccaneer anchovy Encrasicholina punctifer off Mozambique, based on samples collected in research surveys

Growth of Encrasicholina punctifer (Engraulididae) is estimated, based on samples obtained during five surveys on Sofala Bank (central Mozambique). The estimated values of the von Bertalanffy growth function, TL∞=12 cm and K=2.0 yearˉ¹ are compared with results of growth studies elsewhere in the Indo-Pacific region, based mainly on the index Φ=log(sub)10 K+2*log(sub)10L∞ assumed to be constant within species. This comparison is rendered difficult by the uncertain taxonomical status of stolephorid anchovies.

Suitability of sodium lactate as cryoprotectant and its effect on gel forming ability and protein denaturation of croaker fish surimi during frozen storage

The effect of sodium lactate is compared with sucrose + sorbitol + sodium tri-poly phosphate as cryoprotectant on gel forming ability & protein denaturation of croaker surimi during frozen storage at -20±2°C for 90 days was evaluated. The quality of Croaker surimi with 6% (w/v) sodium lactate was examined in terms of biochemical parameters of muscle protein, thaw drip, gel strength and calcium ATPase activity :.omparing with those of surimi added with sucrose/sorbitol & without additive as control. Both the cryoprotectants minimized the negative effects of frozen storage on physico-chemical traits of myofibrillar proteins which was evident from the biochemical and sensory parameters. The residual Ca2+ ATPase activity and gel strength of surimi with sodium lactate were higher than those of control throughout 90 days of storage. Ca2+ A TPase activity and gel strength found a high positive correlation. From the results, it was found that sodium lactate was equally effective in preservation of croaker muscle protein native structure during frozen storage as the sucrose/ sorbitol and also less sweet without any risk of maillard browning.

Effect of modified starch on the shelf life of frozen fish Kamaboko with prepared spinach

Fish kamaboko with spinach was prepared by mixing fish kamaboko with spinach prepared with different combinations of ordinary starch (OS) and modified starch (MS), viz., 40:60, 50:50, 60:40, 100%) MS and 100% OS. The products were frozen at -40°C and stored at -20°C, and subjected to biochemical (peroxide value, total titratable acidity, pH and moisture) organoleptic (appearance, taste and colour), microbiological (total plate count) and physical (folding and expressible water) tests at monthly intervals. Among the different combinations tried, it was observed that fish kamaboko with spinach prepared with 50:50 and 60:40 combinations of OS and MS could be stored for six months at-20°C.

Studies on frozen storage characteristics of fillets from six species of fresh water fishes

Frozen storage characteristics of fillets from six major species of fresh water fishes namely, Labeo rohita, Catla catla, Cirrhina mrigala, Labeo calbasu, Mystus seenghala, and Wallago attu are reported. The biochemical, bacteriological and organoleptic changes in the frozen fillets during storage at -18°C have been followed systematically. Compared to the two species of fresh water cat fishes, the four species of carps studied, had a slightly better storage life. From the organoleptic point of view, fillets of Cirrhina mrigala had the best shelf life.

Lipid breakdown in oil sardine (Sardinella longiceps) during frozen storage

The problem of hydrolysis of lipids and consequent accumulation of free fatty acids and development of rancidity due to oxidation of the lipids are major problems in frozen storage of oil sardine (Sardinella longiceps). The course of the phospholipid breakdown, production of free fatty acids and the changes taking place in the major unsaturated fatty acids during frozen storage are described in this paper. The rate of free fatty acid production is faster in the fish, with the higher fat content. Unlike in lean fish, the neutral lipids are found to contribute substantially to the free fatty acid production. The fatty acids most affected during storage are C sub(20:5) and C sub(22:6). The polyene indices were found to decrease during storage. These effects are more pronounced in the fish with the higher fat content.

A method for the preparation of cooked-peeled-frozen prawns

Several consignments of cooked-peeled-frozen prawns exported from India were rejected last year due to high total plate count (TPC) at 30°C. The specified temperature of incubation for TPC in our country is 37°C. Hence the effect of incubation at 30 and 37°C on TPC was studied. It is seen that the count is higher on incubation at 30°C. A method for production of cooked-peeled-frozen prawns conforming to the specification for TPC at 30°C is standardized and is reported. It consists of recooking the cooked-peeled prawns followed by packing and freezing without further contamination. The method minimizes batch to batch or sample to sample variation in TPC.