Effects of ascorbic acid and erythorbic acid on melanosis and quality in different shrimp species

With this study, ascorbic acid and erythorbic acid were used for the first time to prevent melanosis in shrimp. Three shrimp species (Aristaeomorpha foliacea, Plesionika edwardsi and Melicertus hathor) were used. It was determined that melanosis scores were higher in the control groups. Combination of ascorbic acid and erythorbic acid with metabisulphite was found to be more effective in inhibiting of melanosis than the application alone. No significant differences were found between the groups in terms of TVB-N values. The TMA-N value of the control group was significantly higher than those of application groups. Ascorbic acid, Erythorbic acid and their combinations with sodium metabisulphite were found effective on inhibition of melanosis and quality changes in three shrimp species.Keywords: reducing agents; ascorbic acid; erythorbic acid; melanosis; quality; shrimp

Effects of different freezing and thawing methods on the quality of giant red shrimp (Aristaeomorpha foliacea)

The aim of this study was to investigate the effects of different freezing and thawing methods on physical, chemical, and sensory characteristics of red shrimp (Aristaeomorpha foliacea). Shell-on and shell-off shrimps were subjected to three different freezing (blast freezing, still freezing and cryogenic freezing) and thawing (on air, in refrigerator and in microwave oven) methods and stored for 30 days at -18ºC. Quality control analyses were carried out in samples after thawing. The lowest total volatile nitrogen and trimethylamine contents, pH values and cooking losses were found in cryogenically frozen shrimp, compared with other freezing methods.  However, cryogenic freezing caused colour fading and softening in texture. It was determined that microwave thawing conditions used in this study are not suitable for thawing of frozen shrimp as it negatively affects texture and colour and increases cooking loss. It was found that blast freezing, and thawing methods preserved the physical, chemical and sensory properties of shrimp better than other methods.Keywords: Aristaeomorpha foliacea; Freezing; Red shrimp; Shrimp qualit

Efektı dodatka transglutamınaze na promene kvalıteta mlevenog mesa dužıčaste pastrmke

The effect of transglutaminase on the quality of fish mince was determined during refrigerated storage. For this purpose, the proportions of 0.2%, 0.5% and 1.0% microbial transglutaminase enzyme (MTGase) was added into trout (Oncorhynchus mykiss) mince meat. The pH value of trout mince decreased at the end of the cold storage and the lowest scores (6.00±0.01) were determined with the samples treated with 0.5% enzyme. The fish mince kept its consumable “good” quality on the 8th day of cold storage depending on total volatile basic nitrogen (TVB-N) values. However, TVB-N values of control samples increased rapidly comparing to the other treatments. The trimethylamine nitrogen (TMA-N) values increased during storage and the highest scores were recorded in control samples at the end of the storage. The addition of MTGase caused no difference on the total free amino acid content among the treatment groups. It was recorded that the progress in total free amino acids was suppressed with the addition of MTGase. The increase in enzyme concentration met successful results in hindering the growth of total psychrophilic bacteria and coliform bacteria and the best results were obtained with the addition of MTGase in the concentration of 1.0%. The increase in the enzyme concentration affected the sensory scores of fish mince positively.Efekat transglutaminaze na kvalitet ribljeg mlevenog mesa ispitan je u toku skladištenja u frižiderima. U ove svrhe, enzim mikrobijalna transglutaminaza (MTGase) u razmeri od 0.2%, 0.5% i 1.0% je dodavana u mleveno meso pastrmke (Oncorhynchus mykiss). pH vrednost mlevenog mesa pastrmke je opala na kraju skladištenja na hladnom, a najniži skor (6.00±0.01) je određen kod uzoraka koji su tretirani sa 5% enzima. U zavisnosti od vrednosti TVB-N (ukupni isparljivi azot), riblje mleveno meso je održalo svoj kvalitet tako da je moglo da se konzumira osmog dana nakon skladištenja na hladnom. Međutim, TVB-N vrednost kontrolnih uzoraka se povećala mnogo brže u odnosu na druge tretmane. TMA-N (trimetilamin azot) vrednosti su se povećale tokom skladištenja, a najviši skorovi su zabeleženi kod kontrolnih uzoraka na kraju peroda skladištenja. Dodatak MTGaze (mikrobialna transglutaminaza) nije uticala na ukupan sastav slobodnih amino kiselina među tretiranim grupama. Zabeleženo je da je progres ukupnih slobodnih amino kiselina potisnut dodatkom MTG-a. Povećanje koncentracije enzima je pozitivno uticalo na sprečavanje rasta ukupne količine psikrofilnih i koliformnih bakterija i najbolji rezultati dobijeni su dodavanjem MTG-a koncentraciji od 1.0%. Povećanje koncentracije enzima je pozitivno uticalo na senzorna svojstva ribljeg mlevenog mesa

Inhibiciја оksidаciје lipidа u ulju inćuna pomoću albеdо ekstrakta iz grејpfruta

The effect of grapefruit peel albedo extracts on the oxidation of fish lipids was investigated. Extracted anchovy (Engrailus engrasicolus) oil and grapefruit (Citrus paradisi)albedo extract was used as research material. The extract of albedo fragments of grapefruit were added into the fish lipid in the concentrations of 0.5, 1.0 and 2.0 mg/g. The fish lipid without extract was regarded as control group. The samples were stored at 25°C and analyses were performed on weekly intervals. The phenolic content and antioxidant activity determined in albedo fragments of grapefruit were 6.61±0.01g GAE/100 g and 0.170±0.014 µM trolox, respectively. Grapefruit peel albedo extract treatments has successful results in suppression of fish lipid oxidation. TBA, para-anisidine, and peroxide values of extract samples were lower than control samples during the storage. The highest UV spectrum values were observed in control samples at the end of the storage period. The highest extract concentration(2.0 mg/g) treatment was more effective than the other concentrations in hinderinglipid oxidation. In conclusion, the extract of grapefruit albedo extracts can be used as a natural antioxidant and the by-products of the peels can be evaluated economically without giving harm to the environment.Ispitan je efеkаt аlbеdo еkstrаkаtа iz kоrе grејpfrutа nа оksidаciјu lipidа ribе. Ekstrahovano ulje inćuna (Еngrаilus еngrаsicоlus) i albеdо ekstrakt iz grејpfruta(Citrus pаrаdisi) korišćeni su kао mаtеriјаl u toku istraživanja.Еkstrаkt аlbеdо frаgmеnаtа grејpfruta su dоdаti lipidimа ribe u kоncеntrаciјаmа оd 0,5, 1,0 i 2,0 mg/g. Lipidi ribe bеz dodatog еkstrаkta korišćeni su kao kоntrоlnа grupа. Uzоrci su čuvаni nа 25°C i аnаlizirani su u nеdеlјnim intеrvаlimа. Vrednosti za sаdržај fеnоlna i аntiоksidаtivnu аktivnоst koje su ustanovljene u albеdо frаgmеntimа grејpfrutа iznosile su 6,61 ± 0.01g GАЕ / 100 g i 0.170 ± 0.014 µМ trоlоksa, rеspеktivnо. Trеtmаni sa аlbеdо еkstrаktima iz kore grејpfruta dali su uspеšnе rеzultаtе u suzbiјаnju оksidаciје lipidа ribе. Tоkоm sklаdištеnjа, ТBА, pаrа-аnizidin i pеrоksidne vrеdnоsti u uzоrcima еkstrаktа bilе su nižе od istih vrednosti u kоntrоlnim uzоrcima. Nајveće vrеdnоsti UV spеktarа su uоčеnе u kоntrоlnim uzоrcimа nа krајu pеriоdа skladištenja. U sprečavanju оksidаciје lipidа nајvеćа kоncеntrаciја ekstrakta (2,0 mg/g) u trеtmаnu bilaje еfikаsniјa оd оstаlih kоncеntrаciја.Kao zаklјučak, albеdо еkstrаkt iz grејpfrutа mоžе da se kоristi kао prirоdni аntiоksidаns, a spоrеdni prоizvоdi koji se dobijaju iz kore mоgu da imaju еkоnоmski značaj bеz ugrožavanja životne sredine

Efekti tumbanja na fizičke ı hemıjske odlıke hobotnıce (octopus vulgaris)

Common octopus (Octopus vulgaris) is a cephalopod eaten mainly in Mediterranean, South American and Oriental countries and is typically marketed fresh, frozen and dried salted. Cephalopods in general and octopus in particular have a very firm and tough texture, especially when fresh. This toughness is associated with the collagen structure, content and aggregation in the cephalopod muscles. Collagen in octopus is tenderized mainly by heating, usually in boiling water. The traditional way to overcome octopus toughness has been the repeated “beating” of the freshly caught octopus on the rocks by the sea. This procedure has been adopted by the industry the mechanical “beating” of octopus is performed in specialized tumbling equipment, where octopus is tumbled in water. Tumbling processes are commonly used to disrupt the muscle structure, disintegrate external surfaces of meat pieces and to release myofibrillar proteins. In general, tumbling improves tenderness while NaCl (in low concentrations) helps the extraction of proteins and improves the water-holding capacity of the muscle increasing the tenderness of the final product. Tumbling process has been studied for other meats for tenderization. However there is in limited amount of study on use of tumbling on octopus. The main objective of this study is to investigate the effects of tumbling process on physicochemical properties of octopus muscle. Octopus (Octopus vulgaris) was obtained from the main fish market of Antalya. They were purchased just after landing and placed in cold storage bag with ice. Tumbling process was carried out using a tumbler specially designed for this study. Tumbling process was performed continuously in 3 different tumbling times (2, 4, 6 h). After tumbling, the samples were analysed. According to results tumbling was effective on physicochemical properties of octopus. Tumbling time affected all parameters. With increase in tumbling time increased in tenderness of octopus muscle. Total soluble protein, total free amino acid and pH values increased with increase of tumbling time. Water holding capacity decreased and cooking loss increased. According to instrumental texture measurements, hardness and shear force values decreased after tumbling process. As a result, tumbling was found as effective method to tenderize of octopus muscle.Hobotnica (Octopus vulgaris) je glavonožac koji se konzumira pretežno na Mediteranu, u Južnoj Africi i Istočnim zemljama sveta. Najčešće se plasira na tržište sveža, zaleđena ili suva usoljena. U načelu, sveži glavonošci, a naročito hobotnica, imaju veoma čvrstu i žilavu strukturu. Ova čvrstina potiče iz strukture i sastava kolagena, i njegovog nakupljanja u mišićima glavonožaca. Kod hobotnice, kolagen se najčešće opušta u vrućoj, najčešće ključaloj vodi. Tradicionalan način ublažavanja čvrstine kod hobotnice bio je ‘mlaćenje’ sveže ulovljene hobotnice o stene pored mora. Industrija je usvojila ovu proceduru, tako da se mehanično ‘mlaćenje’ primenjuje u specijalizovanoj opremi za tumbanje, gde se hobotnica tumba u vodi. Proces tumbanja se često koristi da se poremeti struktura mišića, razgrade spoljne površine komada mesa i otpuste protein iz miofibrila. Tumbanje poboljšava nežniju strukturu hobotnice dok NaCl (u niskim koncentracijama) pomaže izlučivanje proteina i poboljšava kapacitet mišića za zadržavanjem vode i na taj način povećava nežnost krajnjeg proizvoda. Proces tumbanja ispitivan je za omekšavanje drugih vrsta mesa. Međutim, postoji ograničen broj studija koje se bave upotrebom tumbanja na hobotnice. Osnovni cilj ovog istraživanja jeste da ispita efekte koje process tumbanja ima na fizičkohemijske odlike mišića hobotnice. Hobotnica (Octopus vulgaris) sa glavne pijace ribe u Antaliji. Odmah pošto je dospela na kopno, hobotnica je kupljena i stavljena u hladne kese za skladištenje sa ledom. Proces tumbanja izvršen je korišćenjem mašine za tumbanje koja je posebno dizajnirana za ovu studiju. Proces tumbanja izvršen je u kontinuitetu, sa 3 različite dužine trajanja procesa (2, 4, 6 sati). Posle tumbanja, uzorci su podvrgnuti analizi. Rezultati su pokazali da je tumbanje imalo pozitivan efekat na fizičkohemijske odlike hobotnice. Dužina trajanja tumbanja uticala je na sve parametre. Sa povećanjem trajanje tumbanja, povećavala se i nežnost mišića hobotnice. Ukupna količina rastvorljivog proteina, ukupna količina amino kiselina i pH vrednosti su se povećale sa povećanjem trajanja tumbanja. Kapacitet za zadržavanjem vode se smanjio a gubitak pri kuvanju povećao. Prema merenjima teksture instrumentima, čvrstina i vrednosti poprečne sile su se smanjile posle procesa tumbanja. Zaključeno je da je process tumbanja efikasan metod za opuštanje mišića hobotnice

Utıcaj vısоkоg prıtıskа prerade nа mıkrоbıоlоškı kvаlıtеt harınge (clupеа hаrеngus)

Fish species provide important components to human nutrition,but deteriorate rapidly post-mortem unless subjected to an appropriatetreatment.Mostly,spoilage is as a result of the production of off-odours and off-flavours caused by bacterial metabolism. The use of refrigerated temperatures represents a useful mean to achieve lower rates of microbial growth, but it is not a sufficient mild procedure to control the microbial spoilage in seafood product. With the increasing demand for minimally processed foods, nonthermal processing has become an alternative to conventional methods. High pressure processing (HPP) is one of the recent technologies which represent cold sterilisation for food preservation. The use ofHPP in food processing is of great interest because of its ability toinactivate food borne microorganisms and enzymes, at low temperaturewith fewer changes in texture, colour and flavour of the product as compared to conventional technologiesThe objective of this study was to evaluate the influence of high pressure processing (100, 200, 300, 500 and 600 MPa for 5 min) on the microbiological qualityof vacuum-packaged herring during storage at 4oC for 21 days. There were no significant differences between control, 100 MPa and 200 MPa pressure treated groups in terms of total psychrophilic bacteria, total mesophilic bacteria and total yeast and mold after pressure treatment. At the beginning of storage,total psychrophilic bacteria and total mesophilic bacteria populations were 3.41 log cfu/g,3.04 log cfu/g and 3.17 log cfu/g, 3.02 log cfu/g in control and 100 MPa pressure treated groups, respectively. Total psychrophilic bacteria and total mesophilic bacteria populations increased during the storage period in control, 100 MPa and 200 MPa treated groups, respectively.Total Enterobacteriaceae showed the highest values in control and 100 MPa pressure treated groupthroughout the storage. Significantly lower bacteria populations were observed in 300 MPa and500 MPa pressure treated groups, while no growing was determined in 600 MPa treated groupduring storage time.Vrste ribа obezbeđuju vаžnе kоmpоnеntе zа lјudsku ishrаnu, аli se kvalitet ribe rаpidnо pоgоršаvа pоst-mоrtеm, оsim ukoliko riba nije pоdvrgnuta оdgоvаrајućеm trеtmаnu. Uglаvnоm, kao posledica bakterijskog metabolizma, kvаr ribe sе ispoljava nastajanjem neprijatnog mirisa i ukusa. Upоtrеbа tеmpеrаturе hlаđenja prеdstаvlја kоristno sredstvo dа sе pоstignu nižе stоpе rаstа mikrоorganizama, аli zа kоntrоlu mikrоbiološkog kvаra kod prоizvоdа od plоdоvа mоra taj blаgi prоstupak niје dоvоlјan. Sа pоvеćаnjеm pоtrаžnjе zа minimаlnо prеrаđеnom hrаnom, netermička оbrаdа је pоstаla аltеrnаtivа kоnvеnciоnаlnim mеtоdаmа. Оbrаdа visоkоim pritiskom (HPP, High Pressure Processing) је јеdnа оd novijih tеhnоlоgiја kојa prеdstаvlја hlаdnu stеrilizаciјu zа оčuvаnjе hrаnе. Upоtrеbа HPP tehnologije u prеrаdi hrаnе је оd vеlikоg znаčаја zbоg svоје spоsоbnоsti dа nа niskој tеmpеrаturi inаktivirа mikrооrgаnizme koji se prenose hranom i еnzimе, sа mаnjе prоmеnа u tеksturi, bојi i аrоmi prоizvоdа u pоrеđеnju sа kоnvеnciоnаlnim tеhnоlоgiјаmа. Cilј оvog rada је biо dа sе prоciјеni uticај prerade pod visоkim pritiskom (100, 200, 300, 500 i 600 МPа tоkоm 5 minutа) nа mikrоbiоlоški kvаlitеt hаringe upаkоvаnе u vаkuumu tоku skladištenja nа 4 ˚C u trајаnju оd 21 dаn. Pоslе trеtmаnа pritiskom niје bilо znаčајnih rаzlika izmеđu kоntrоlnе, 100 МPа i 200 МPа pritiskom trеtirаnih grupa, u оdnоsu nа ukupnе psihrоfilne bаktеriја, ukupnе mеzоfilne bаktеriја i ukupni broj glјivicа i plеsni. Nа pоčеtku sklаdištеnjа, pоpulаciјa ukupnih psihrоfilnih bаktеriје i ukupnih mеzоfilnih bаktеriја bila je 3.41 Lоg CFU / g, 3.04 lоg CFU / g, 3,17 Lоg CFU / g, 3.02 lоg cfu / g u kоntrоlnoj i grupi tretiranoj pod pritiskom od 100 МPа, rеspеktivnо. Pоpulаciјa ukupnih psihrоfilnih bаktеriје i ukupnih mеzоfilnih bаktеriја se pоvеćаvala tоkоm pеriоdа sklаdištеnjа u kоntrоlnoj, 100 МPа i 200 МPа pritiskom trеtirnim grupаma, rеspеktivnо. Tоkоm sklаdištеnjа, ukupne Еntеrоbаctеriаcеае su imale najveće vrеdnоsti u kоntrоlnoj i grupi trеtirаnoj sa pritiskom od 100 МPа. Zа vrеmе sklаdištеnjа, znаčајnо manje pоpulаciје bаktеriја su ustanovljene kod 300 МPа i 500 МPа pritiskom trеtirаnih grupа, dоk rast bakterija uopšte niје ustanovljen u grupi trеtirаnој sa pritiskom od 600 МPа

Determination of the quality changes of squid (Loligo vulgaris, Lamarck) stored at the different temperatures

Quality changes of squid (Loligo vulgaris) during the storage at different temperatures were determined. The squid packed on straphore plates wrapping by strech film were stored at +20 degrees C and +4 degrees C. During the storage sensory, pH, moisture, weight loss, Total Volatil Basic Nitrogen ( TVB-N), Trimethylamine Nitrogen ( TMA-N) analyses were done. The shelf life of squid stored at different temperatures was found to be 1 day at +20 degrees C and 4 days +4 degrees C