Use of Tripolyphosphate in the Development of Products from Minced Fish Meat

SUBRATA BASU

Research Centre of Central Institute of Fisheries Technolvgy. Kakinada - 533 003

Sodium tripolyphosphate can be used with several advantages in dried products prepared from minced fish. It lowers the water activity (aw) of the product and has got bactericidal property. It increases hydration ofthe protein and increases resistance to thermal denaturation of the protein.

In India, we face the problem of under also prepared with minced meat where no utilization of deep sea bycatches leading to polyphosphate was used. Water activity the uneconomical commercial fishing. Besides of the cakes was measured by equilibrating few commercially important species, most of the samples at different RH (Stockes & the newly landed species, find less accepta- Robenson, 1947) and measuring percent bility with the consumer due to nonfamili- equilibrium moisture content at a particular arity. Development of acceptable pro- temperature by isopiestic method (Bull & ducts from minced meat obtained from these Breese, 1970; Chattoraj & Mitra, 1977). species may solve the problem of non acce- The samples were equilibrated for 48 h and ptability thereby fetching good remuneration moisture content of equilibrated samples for landing from deep sea trawlers and lin- were determined by AOAC (1975) method. ding a solution to protein malnutrition. Minced meat from sciaenid was mixed Basu et al. (1985) developed fish cube, thoroughly with 0.2, 0.4, 0.7 and 1.0% sodium dried fish cake from raw minced meat. tripolyphosphate and kept for 1.5 h at room The product contains 11-12.5% moisture temperature (30°C). Total bacterial count and has four months shelf life. The pro- of all the polyphosphate treated samples duct has got tough texture. It was felt neces- along with blank was determined by standard sary to find out some chemical which will pour plate method using tryptone glucose improve the texture and shelf life of such agar medium. products. The possibility of use of sodium tripolyphosphate for the purpose is descri- Actomyosin from fish muscle was prepared bed in this paper. following the method of Herring et al. (1969). Specific viscosity of actomyosin solution was Materials and Methods measured by Ostwald viscometer at temperatures ranging from 28 to 50°C dipped in a Minced meat from sciaenid was obtained specially designed thermostatic bath atta- by passing tillets through meat mincer. Min ched with insulated cover. Servo - therm ced meat was mixed thoroughly with 0 4 and oil was used in the bath. The temperature 0.7% sodium tripolyphosphate and dried in ofthe bath could be adjusted within 1- 0.01 °C. sun upto 50% moisture in the form of small Fifteen minutes time was allowed for the cakes (1.5 x 1.5 x 0.5 cm size). Cakes were solution to attain the bath temperature.

FISHERY TECHNOLOGY TRIPOLYPHOSPHATE IN THE DEVELOPMENT OF FISH PRODUCTS 37

Flow time (t) of 5 ml atomyosin solution at acts as an agent for reducing water activity. different temperatures was noted. Flow Reduced “w will allow more moisture con- time for the blank at different temperatures tent in the product with consequent less is represented as to. Specific viscosity (V/sp) toughness and longer shelf life. at a given temperature was then calculated based on the equation: Table 1 shows the total bacterial count of "SD li 11 minced meat samples treated with different 0 concentrations of sodium tripolyphosphate For each proteinisolution in different salt and also of control. Treated sample showed solution (0.6 M NaCl solution and 5% less bacterial count as compared to control. sodium tripolyphosphate solution) nw/C As the concentration of tripolyphosphate was plotted against temperature so that a increased, the total bacterial count decreased melting profile of fish actomyosin in each gradually, showing bactericidal property of case was obtained. sodium tripolyphosphate. This property will ensure longer shelf life ofthe product. Fig. 2 Results and Discussion shows the hydration characteristics in terms of percentage of water absorbed at equili- at different of dried cakes Fig. 1 shows the plot of percent equilibrium RH fish brium moisture content against water acti- treated and not treated with sodium tripoly- vity (aw) of fish cakes treated with 0.4 and phosphate. For both samples the percent 0.7% sodium tripolyphosphate and also of equilibrium moisture content is very low control where no polyphosphate has been below 80% RH. Above 90% RH, equili- used. lt is clear from the iigure that sodium brium moisture content for treated sample tripolyphosphate reduces the “w of the is very high whereas the value for the untrea- product and as concentration increases, the ted control is very low. This shows that “W further decreases. At a particular equili- rehydration of the dehydrated product where brium moisture content,say 15 % the con- tripolyphosphate has been used will lead trol cake shows “w of 0804, the cake with to good hydration of the protein giving a 0.4% tripolyphosphate 0.776 and that with product with less toughness and good 0.7% tripolyphosphate 0.75. So it can be juicines. concluded that sodium tripolyphosphate Table 1. Total bacterial count in presence 50 ofd{0"erent concentrations ofsodium >-- O 4% Tnpolyphosuhate -' ~~ 07% -ao- tripolyphosphate Nl- ° Control Sodium tripolyphosphate Total 25- ,,~‘ s . concentration, % bacterial U. f / 5 count/g * _f ~ _, '_,,/ E __ 1.3 x l0‘ 55- Y__,r"" ,-' Nil(control) 0.2 1.1 x 10' ,__ ~=» r; 0.4 9.3 x 10' 0.7 6.2 x IO’ 5 2.0 x 10’ O7 075 ofto cts 1.0

Fig. 1. Plot of equilibrium moisture content against water activity of fish cake. * Average of three replicates

Vol. 27, 1990 38 SUBRATA BASU

Thermal transition (denaturation) of fish globular protein the mid point of sharp rise actomyosin in presence of 0.6 M NaCl and region of usp/C is taken to point out melting 5% sodium tripolyphosphate are presented temperature (Chattoraj & Mitra, 1977). In in Fig. 3 in the form of usp/C against tem- this case there are two sharp falls in nw/C. perature. Several authors (Mitra & Chat- The two falls possibly indicate the thermal terjaj, 1978; Stainsby, 1958; Hamaguchi & transition of two fraction, one for actin Geiduscehk, 1962; Von Hipple & Schelich, and another for myosin. The intermediate 1969; Tonomura et al., 1962) have studied rise may be possibly due to the trace amount the thermal transition of proteins and nucleic of globular fraction of actin (Fribarg, 1976). acids by measuring nm,/C as a function of However from these data it is not possible temperature. For globular protein thermal to identify which particular fall is due to a transition is known to be accompanied by particular fraction. It is also seen that the a sharp increase of nw/C in a very narrow middle of the up transition region is the range of temperature. But, for elongated average of the two extreme transition region. molecule, thermal transition is accompanied Hence it seems logical to denote this parti- by a sharp fall in viscosity and hence cular point as the melting temperature of Um,/C. So for thermal transition study, it the composite protein actomyosin. From is logical to take the region of sharp fall of Fig. 3 it is seen that denaturation tempera- 1181,/C as the melting region. Melting tem- ture of fish actomyosin in presence of 0.6 M perature in such cases can be taken as the NaCl is 36.8°C whereas in presence of 3% mid point of the transition region. Also for sodium tripolyphosphate, denaturation temperature is 45°C. So use of sodium tripoly- '50 ’*’° ControI_ ~---~ 05% `l?|po|yphdsUhu1e é phosphate in fish cake will resist thermal denaturation upto 45°C. This will give a product with less toughness. s |00 I 1; J So a single chemical, sodium tripolyphos- in- 6 2 so /V phate, reduces the water activity, acts as /. // bactericidal agent, improves hydration of , - "1 protein and resists thermal denaturation __ :-- _-----f.;i_ _- W (QQ 70 150 *eo vo so 90 too upto 45°C. So this chemical can be used PCUWW f\|Vi|fy.% advantageously to develop dried products Fig. 2. Plot of equilibrium moisture content against relative humidity of fish cake. like ish cake from minced fish meat with good texture (less toughness) and longer shelflife. 2° »-- o em Soaium cnioi-me i e -¢ 5°/Q Sodium Wtuolyohosohcvei 230 The author wishes to thank Dr. C.C. Panduranga Rao, Scientist-in-Charge, Research Centre of Central Institute of Fisheries Technology, Kakinada for his -~?2O0 o\ ` help and guidance in carrying out this work and 8 Shri M.R. Nair, Director, C.I.F.T., Cochin for the \Q2lO //\ permission to publish this paper. Q .a P2 . \ References L) C _____ .____.,¥ _ . , V, L_ 28 35 38 43 48 `l'erv~peru'ure 'C AOAC (1975) Official Methods of Analy- Fig. 3. Plot of "sp/C against temperature of acto- sis (Horwitz. W., Ed.) 12th edn., Asso- myosin in 0.6 M NaCl and 5% sodium ciation of Oliicial Analytical Chemists, tripolyphosphate. Actomyosin content in both the cases is 0.002 g/ml. Washington, D.C.

FISHERY TECHNOLOGY TRIPOLYPHOSPHATE IN THE DEVELOPMENT OF FISH PRODUCTS 39

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