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STUDIES ON THE EFFEfX OF CamANSI I CnRZrs JUICE ON THE PRESERVATION OF SUME OR SHRIMPS { GENUS PEWUS ) S.V. Bersamin. AS. Legaspi and N.G. Macaiincag ABSTRACT TWOsets e xperirnents (packing in c&mansi juice ice, dipping in calarnansi bite and packing in ordinary ice) conducted to determine the efficacy of calamansi (atype of citrus fruit simjrar to lemon ) juice in prolonging the freshness of shrimps, show that calamansi juice inhi bits the growth of microorganisms on the flesh of shrimps, retards proteolytic decomposi- tion which is usually characterized by the development of fishiness,blackening of the head and tail and loosening of shells, and inhibits devdopment of strong off-odors. ZNTRODUCTION is widdp cultivated in the Philippines and One of the major problems ic the com- bears fruits the year round. At certain sea- mercial handling of fishery prdccts is the sons it rows in abundance and becomes very prevention of the deteriorative changes which cheap. It is readily available in most markets make them unacceptabie to the discrimina- and stores in the Ybilippincs. ting consumers. Fish starts to deteriorate Analysis of calamansi (per 100 grams) :* immediately after catching, and no method Edible portion, 40% of preservation has yet been devised ta keep Moisture, g 89.9 Fat, g 0.6 them absolutely fresh. For this reason it is Carbohydrates,g 0.3 necessary that some precautionary measures Ash, g 8.9 be taken 13order to slowdown ihe deteriara- Calcium, mg 22.0 in tive changes that take p:ace fish and other Phosphorus, mg 12.0 fishery products. Deterioration m fish is Iron, mg 1.5 primariIy due to tnzyrnes and bacteria pre- Sodium, mg 2.4 sent in them. Among the various methods Potasium, mg 800.0 of preservation, icing is the most practical Thiamin, mg 0.02 especially if the fish is to be sold as fresh. Rivotlavin, mg 0.01 However icing preserves fishery products Niacin, mg 0.01 for only a limited time, especially when fish Ascorbic acid, mg 40.00 is subjected tcl too much handling and trans- Citric acid 3.6- 3.7 g./100 g. of juice- porting. The Philippine calamansi is the coan- The accompanying experiment aims tu terpart iemon in other countries. Cab- improve the icing method now being em- mansi and lemon have more or less the same ployed by commercial handlers of fishery pro- acid contents ( ascorbic and chic ) which arc ducts, through the use of an inexptnsivr responsible for their preservative tEect. Cilw microcarpa or native frait, Bungt Czfnu 111 a detailed study on the chemistrY i~cornmonlyknown as cahmansi. The tree -- - -- - - - of shrimp whicb was published by the Sunkist * Data mppliPliHI1 by the Fwd acd Nutritiw Genre: and the Bu Growers, Ontario, California ( " The Effect to have an inhibitory effect on the strains of of Lemon Juice in Shrimp Processing"), the Psdmwws sp. Growth of microorganisms in factors associated with the aging of shrimp a medium containing ascorbic acidis inhibited and the breakdown of shrimp tissues result- by the increase in acidity and release of hy- ing in a strong fishy ammoniacal odor were drogen peroxide in the medium. determined. The properties of lemon juice Fauikner et a1 ( 1954) state that " black which make it an effective preservative were spots " is a condition in shrimp characterized explored and concf usions were made that : by the development of a black coloration lemon juice is an. effective anti-oxidant and which starts from the head and spreads to a bufiered acidic system capable of great She tail, where it forms black bands outlining dilution; it inhibits the growth of microor- the sections of the tail region. Unless they ganisms which affect shrimp flesh and that iced immediately, blackening may begin lemon juice retards the enzymatic action are within a few hours after death of the shrimps. producing the darkening of sea-foods as- However, breakdown. even with continuous icing, black- sociated with proteoly tic Other enhg may be far advanced before the catch conclusions were: certain ingredients in lemon can be marketed. This is a predicament juice are good sequestering agents and will usually encountered in the handling of suppress the effects of metals such as iron shrimps in the Philippines. and copper in promoting unwanted chemical reactions in sea foods; lemon juice neutralizes Hardening and darkening of the cuti- or keeps lobster or shrimps from becoming cles of lobsters were due to the enzyme tyro- alkaline thus preventing the disagreeably sinase. Fieger ( 1951) presented the first strong '' fish-like " odors from developing; evidence for the enzymatic nature of the certain combinations of ingredients in lemon blackening reaction in shrimps. Fieger es- juice contribute to the freshness and flavor tablished that bacteria was not instrumental enhancement in seafoods; and that lemon in bringing about blackening. If it could be juice has a very low surface tension which definitely established that blackening in makes possible rapid penetration in solid shrimp is due to the enzyme tyrosinase, mea- foods and increase its effectiveness. sures found effective ininhibiting the enzyme in other sources might be adopted to control An experiment done by Luther and the black spots in shrimps. The work herein Grawall ( 1946 ) reveaIed that citric acid and presented was undertaken to obtain further ascorbic acid added to apples retained their evidence for the enzymatic nature of the natural color. The experiment also revealed black spots and to explore methods of retard- that citric acid inactivates the enzymes of ing the reaction in shrimps. the fruit. The combined use of citric and ascorbic acids produced improved anti-axi- It is surmised that calamansi which is dant properties over citric acid alone. This a cheap source of ascorbic and citric acids, natural combination of citric and ascorbic hence a reducing agent, would be a controling acids are found in the local calamansi. measure for the retardation of darkening in shrimps. Refrigerated shrimps may be able In another experiment conducted by to retain their quality when covered by lemon Watts and Techmann ( 1952 ) on the use of juice solutions. From the work of Faulkner ascorbic acid on meats, it was revealed that ( 1954 1, it was found that ascorbic acid and the addition of ascorbic acid to refrigerated sodium ascorbate in concentrations ranging ground meat resulted in the " brightening I' from 0.05% to 0.5% were effective in pre- of the meat surfaces after a few days venting darkening of cuticle extracts in the storage in the refrigerator. presence of added phenolic substrate as well Costilow ;1955 ) states that ascorbic as inhibit blackening of beads or whole acid in 0.1 per cent concentration was found shrimps as long as thelatter remainin solution. In another instance, lowered pH of shrimp toughening effect, which was noticed after medium decreases the activity of the enzyme the seventh day of observations of calamansr tyrasinase. ice on the shrimp, the confirmatory expcrr- was The foregoing experiments tend ta ment altered. prove that cal smansi juice lengthens the Experimental groups for tbe confirma- f redmess of refrigerated shrimps. tory experiment were the following : Batch No. I was packed in ordrnar y ice EXPERIMENTAL METHODS Icontrol ). Seven hundred pieces of ripe calamansi BatchBo. 2 was dipped ita a I: 30 cal- fruits and 4 kg. of shrimp or suabe (Pnraeur) amansi solution and packed in were purchased from a local market. The ordinary ice. juice was extracted from the fruits and the Batch No. 3 was dipped in a 1 :20 cai- various concentrations needed in the experi- amansi sdution and packed in ment were made using tap water as the dr- ordinary ice. hent. Calamansi ice was prepared by mixing Batch No. 4 was d~ppcdin a 1 : 10 cal- one part of caiamansi juice to forty parts of amansi solution and packed in water and placed in a deep freezer where tne ordinary ice. solution was converted to ice. The shrimps TBC were washed thoroughly with tap water, The and organoleptic observations on raw arid cooked samples were made dzily drained and divided into four batches, and the on the experimental batches. The shrimps initial total bacterial count taken for each used in tbis experiment having been purchas- batcha The first batch was packed in ordinary ed from a local market were not in a very ice to strve as control. The second batch fresh state. The samples were refrigerated was packed in calamansi ice ( 1 : 40 calam- at a temperature rqgiog from-5.0% to-8.0'C. ansi solution frozen into ice ). The third batch Ice was replaced when melted. Proximate was dipped in calamansi solution ( 1 : 20 ) for chemical analyses were madc on the samples a period of 10 minutes and packed in ordinary before and after the completion of the ex- ice. periments. The total bacterial count ( TBC ) of the of different experimentaf batches were taken For purposes idcntificataon a code was at periodic inter vds. Organoieptic observa- made to represent the various sample tions on raw and cooked samples were also batches used in the two experiments: madc daily throughout the period of the in- Experiment 1 Experiment 2 vestigation. Batch No. 1 C C Two qets of experiments were made. Batch No. 2 CI C, The Grst aimed at finding the concentration Batch No. 3 D %, of calamansi solution for dipping and the Batch No. 4 DCI proportioc of caiamansi juice in the prepara- C,* tion of calamansi ice which would be most effective in preservin~ the freshness af RESULTS .4ND DISCUSSIONS shrimp. The second experiment served to The resu1:s art shown in Tables I, 11, confirm the result of the first.

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