PPT FISH

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food science and cosmetic analysis

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FISH:

FISH By Gudela.Parimala M.pharm,1 st year p’ceutical analysis & QA Raghu college of pharmacy

Introduction:

Introduction Commercial fish mostly comes within the following classes: Fatty fish- Eg; herring,mackerel Round white fish- Eg; Cod,haddock Fresh water or anadromous fish- eg; salmon, trout Flat white fish- Eg; plaice,halibut These four classes are Teleosts i.e, have bony skeleton. Other classes are… Elasmobranches : -have cartilaginous skeletons. eg; skate, Dogfish Shell fish include crustacea & molluses. crustacea-have jointed outer skeleton eg; crab,shrimp, prawn. molluses- have snail like univalves eg; periwinkle, whelk. - have bivalves with double hinged shells eg; oyster , mussel

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COMPOSITION The main constituents of fish are Water , Protein , Fat. Some examples of compositional data for various species are: CLASS SPECIES WATER% FAT% PROTEIN (N*6.25)% White round Cod,haddock 79-84 0.1-0.9 15-20 White flat Plaice 77-81 0.5-4.0 16-19 Halibut 75-80 0.5-9.5 15-19 Fatty fish Herring 60-75 7-30 14-20 mackerel 60-75 2-20 17-35 Fresh water Salmon 67 0.3-15 16-24 Shell fish Crab,fresh 73 5 20 oyster 86 1 11 Elasmobranch Skate 77-82 0.2-2 18-24 Dog fish 75 4-6 20

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In general fish is better source of vitamins & minerals than meat. White fish flesh contains little of vit A&D,but fatty fish are rich in vit D. The amount of B group vitamins present in fish is about the same in meat. Fish is good source phosphorus & magnesium compared with lean meat. It contains 100 times more iodine,less iron and same amount of copper.

LEGISLATIONS AND STANDARDS:

LEGISLATIONS AND STANDARDS The main interaction of legislation with production and sale of fish relates primarily to public health aspects of harvesting, handling &processing. The principle enactments are public health regulations 1934 and the therapeutic substance(preservation of raw fish)regulation 1964. The provisions of food hygiene regulations are supplemented by two codes of practice on handling of fish during transportation and retail.

Inspection and examination of fish:-:

Inspection and examination of fish:- Fish is inspected for the presence of parasites and diseases and also quality assessment, a term which usually refers to the degree of spoilage. Parasites such as worms & lice have occasionally been reported in fish, but as they tend to residue in the stomach & intestine they are removed during gutting. Diseases causing tumors, ulcers & boils have also been reported in fish, but poisoning in humans due to the ingestion of fresh or unprocessed fish – It is rare. Shellfish have been the cause of several poisoning. Cont……..

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As fish spoils, various physical changes occurs, i.e. odour deteriorates, the surface becomes turbid, flesh softens, the eye pupil becomes turbid and a reddish colouration develops along with back bone. In some cases, chemical determinations may be considered. Prawns & shrimps should be examined for added dyes such as Carmoisine . Frozen prawns imported from North America, have been found to contain erythrosine, tartazine etc.

Analysis of Raw-fish:

Analysis of Raw-fish Sample preparation :- The method of preparation of sample depends on the form in which the fish is received and analysis to be carried out. For proximate analysis of frozen fish first place it in a plastic bag Thaw by immersion in a agitated water bath approximately at 20 ⁰ C. Judge the completion of thawing by gently squeezing the bag until no hard core or ice crystals can be felt. Render the thawed or wet fish into uniform mass either by double mincing or used of an electrical driven rotary chopper. cont…..

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Store the sample in a air tight container. Analyse as quickly as possible. If storage is necessary keep at a temperature not exceeding 4 ⁰ C. For estimation of amines & total volatile bases for frozen fish, thaw at a temp not exceeding 4 ⁰ C, mince or chop in rotary homogenizer. Ensure that the product remains at or about 4 ⁰ C by pre-cooling the equipment. Mix the sample and Analyse immediately.

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Assessment of spoilage of Raw fish :- Fish spoils somewhat rapidly and analyst is called upon to assess its edibility. Spoilage of fish stored in ice is due to bacterial and enzymic action which results in the production of various volatile compounds, in particular trimethylamine (TMA), dimethylamine (DMA), ammonia & volatile acids. Trimethylamine oxide is reduced during spoilage to TMA and the ammonia formed is mainly a product of protein breakdown. The amount of TMA & Total Volatile nitrogen (TVN) i.e. volatile amines + Ammonia) are most commonly used for assessing the degree of spoilage in white fish.

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The TMA & TVN contents are often determined by the conway micro-diffusion technique or by semi-micro steam distillation. The TVN can be readily determined, without any special equipment by employing the following macro distillation method . Determination of total volatile basis and TMA in Flesh foods: The method recommended by the AMC (1979) for determination of TVN & TMA is based on a semi- microdistillation procedure. Extracts or solutions are made alkaline with sodium hydroxide ( NaOH ). The basis are steam distilled into standard acid and back titrated with standard alkali. Formaldehyde is added to a neutralized mixture and the acid released is equivalent to the volatile basis other than TMA.

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Procedure:- Weight 100 grams ± 0.5 of prepared samples into a homogenizer with 300 ml of 5% m/v trichloroacetic acid . Run the homogenizer to obtain a uniform slurry filter or centrifuge to obtain a clear extract. By pipette transfer 5ml of the extract to a semi- microdistillation apparatus. Add 5ml 2M sodium hydroxide ( NaOH ) solution , steam distill, collect in 15ml 0.01 M standard Hcl . Add indicator solution(1% rosolic acid in 10% v/v ethanol). Titrate to a pale pink end point with 0.01M. Sodium hydroxide + add 1ml 16% m/v neutralized formaldehyde for every 10ml liquid in a titration flask. Titrate liberated acid with 0.01M sodium hydroxide multiply the titration by 14 to obtain TVN & TMA.

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CALCULATION : Total base nitrogen= [14(300+w) * V 1 ] m g /100 g 500 TMA nitrogen=[ 14(300+w)*V 2 ] mg/100 g 500 V 1 =volume standard acid consumed in the first titration. V 2 =volume standard acid released in the second titration. W=water content of the sample mg/100 g

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 A calorimetric method for determining TMA in fish using picric acid, has been described. White fish :-using the Lucke and Geidel method. White fish can be considered as fresh if the amount of TVN<20mg N/100 g Fatty fish:- The rancidity (smelling or tasting like not fresh) of the fat is a more useful criterion than the TVN. The rancidity values can be determined on a chloroform macerate. Fresh water fish:- Quality can also be assessed from fat rancidity values. Fresh water fish contain little trimethylamine oxide. So that the volatile N formed consists almost entirely of ammonia. Elasmobranch fish:- Using macrodistillation at atmospheric pressure the volatile N which comes over from dogfish & skate includes a considerable amount of ammonia. Vaccum distillation at 50 degree C, however, determines only the TVN present when the fish is sampled.

FISH PRODUCTS :

FISH PRODUCTS Fish fingers Smoke cured fish Canned fish Fish cakes Frozen fish

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Frozen fish: Storage of fish below -18 ⁰ C causes a marked extension of the storage life over chilling in ice. Fish should preferably be quick frozen, i.e. the thermal arrest time to go from 0 to 5 ⁰C should not exceed 2 hrs, so that the degree of protein de- naturation and the amount of drip produced on thawing are both seen Degree of protein de- naturation can be assessed by the cell fragility test. Determination of TVN is usually of little use in frozen fish, but fat rancidity values are sometimes of value in assessing the quality of fatty species The codex alimentarius commission has recommended international standards for frozen fish i.e. gutted pacific salmon ( CAC /RS 36-1970) Fillets of cod and haddock( CAC/RS 50-1971)

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Fish fingers These are usually prepared from cod . The skinned fillets are cut into finger bars , then passed through batter and bread crumbs on a continuous belt . The fingers are then fried in vegetable oil . Packed into wax –wrapped cartons to reduce moisture loss during storage and quick frozen in plate freezer . Most fish fingers contains 57-65 % water ,10 -14% protein , 6 -10% fat and 1-2% ash .

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Smoke-cured fish Most cured fish is smoked over wood after dry salting or immersion in wet brine ( salt water ). Most types are smoked below 38⁰ C but temperature above 90⁰ C are employed for smokies . Wood smoke contains formaldehyde , acetone, acids, phenols ,tar, alcohols. Salting causes a weight loss up to 30% and smoking process 5-25% in fish . Also salt content rises to 2- 4% in most smoke – cured fish but these are most present in smokies (3-5%). Analytically the salt content can be determined by the direct maceration method.

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Smoked cured fish

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Canned fish Fish is normally canned in brine or vegetable oil. Among the commonest fish canned are salmon, sardine, herring . Typical compositions of some types of canned fish: Water Fat Protein(N*6.25) ash Salt pilchards 64 15 19 2 1.4 Salmon 57-70 5-10 19-24 2-4 1.4

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The codex almentarius commission has recommended international standards for canned fish i.e. pacific salmon (CAC/RS 3-1969), shrimp or prawns (CAC/RS 37-1970). The main analysis which should be carried out on canned fish are determinations of trace elements, particularly of tin ,lead ,mercury, arsenic.

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Fish cakes Fish cakes are usually made from pre-cooked fish , a filler (often mashed potato ) ,seasoning (salt, spices etc). The moulded cakes are either fried in batter , baked or may be un cooked and they are often coated with bread crumbs. The analysis of fish cakes is that the determination of water, fat ,protein, ash and salt. the amount of fish can be calculated by the following formula Total white fish %= %total N-0.015*%carbohydrate * 100 2.85

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GELATINE Mainly because of its jelly forming properties gelatine is present as an ingredient in a number of foods In the manufacture the collagen present in waste material such as skin and bones is converted to gelatine by simmering (boiling) with water Two process are developed for the manufacture i.e. , acid extraction Lime extraction Lime gelatine usually has a higher ash , calcium content & its solutions has higher pH than an acid gelatine. The higher calcium content of lime gelatine tends to form insoluble salts in some foods.

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The two types are best distinguished from iso-electric point(IEP),which is at a PH>8 for acid gelatine & PH>5 for a lime gelatine. Composition: The ultimate composition of gelatine is approx. carbon 50.5%,hydrogen 6.7%,nitrogen17.9%,sulphur 0.6% & oxygen 24.3% In determining gelatine (dry protein) the appropriate kjeldahl factor is total N*5.55. Manufactured gelatine contains 12-17% moisture & upto 2.55 ash. Tannin solutions and platinum salts precipitates gelatine, but iron , lead , copper& gold salts do not. It is soluble in acetic acid but insoluble in alcohol or ether.

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Analysis of gelatine : The routine examination of gelatine in laboratories normally include simple setting test prescribed in the order together with in determination of ash ,trace elements , sulphur dioxide and acidity Industrially other common determinations are those for calcium ,iron and moisture and assessment of various physical properties such as eg: jelly strength , colour ,clarity and pH value A bacteriological examinations is also of special importance industrially , particularly if the gelatine is to be incorporated in preserved flesh products. Cont……

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Moisture Ash Calcium and iron Sulphur dioxide Acidity pH value Jelly strength Analysis:

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Moisture: weigh 1 gm into a metal dish + 10 ml water allow to soak place on the water bath to dissolve the gelatine and evaporate off water complete drying in oven at 100⁰ C for 18±1hr The moisture content is not as useful measure for assessing quality as with out other materials In fact a low moisture content may imply poor quality as excessive heating during drying process this leads to protein degradation with consequents loss of jelly strength .

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Ash: Incinerate carefully 5g at 500-550⁰C. Some workers prefer the sulphated ash. Calcium & iron: Ash 10g boil it with 10ml of 5M Hcl & filter the extract into 100ml vol. flask make the filterate upto the mark & use 50ml for estimation of calcium by dissolving the oxalate ppt. in sulphuric acid & titrate with permanganate calcium in excess of about 0.3% indicates the properties of a lime gelatine

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Iron: Ferric iron Imparts a reddish brown tinge to the gelatine solution. Use 5 -25 ml of the solution for the estimation of iron by a suitable calorimetric method. Sulphur dioxide: Determine by iodine method.

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Acidity: Dissolve 2 gm in 50 ml of water on water bath and titrate with 0.1 M NaOH using phenolphthalein. Formerly the BP required that gelatine for pharmaceutical purposes should not require more than 5 ml 0.1 N alkali.

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pH value: It is determined on a 1-2% solution . The pH value may vary from about 4.0-6.3. Higher values in this range suggest the presence of lime gelatine. Jelly strength: Can be measured in absolute units on the bloom gelometer or more easily using Boucher jelly tester. Colour &clarity are also important industrially & can be approximately assessed in the solution prepared for the jelly strength. Solutions for jelly strength must be prepared by soaking in cold water for 1-3hrs & then dissolving at 60 ⁰C(higher temperatures tend to cause loss of strength).

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