Hayvansal kaynaklı gıdalarda ısısal işlemlerin protein kalitesi üzerine etkisinin çeşitli yöntemlerle değerlendirilmesi

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Tarih

1993

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Yayıncı

Ege Üniversitesi

Erişim Hakkı

info:eu-repo/semantics/openAccess

Özet

Proteins occupy a unique status among the constituents of biological matter by virtue of their relatively large size and complex, multif aceted and multireactive structures. These properties of food protein can exert profound changes on the functionality and nutritional quality of the protein. There are a number of degradative reactions resulting from the processing or storage environment which can cause undesirable changes in protein. In this study, nutritive value of the reference protein casein was evaluated by the biological methods using Protein Efficiency Ratio (PER), Net Protein Ratio (NPR), Nitrogen Utilization (NU), and Food Conversation Efficiency (FCE). Moisture, protein contents and in vitro protein digestibility (using three different methods) of casein, raw milk, sterilized milk, dry milk (0 month), stored dry milks (4, 6, 12 and 18 months), raw Rainbow trout, broilled Rainbow trout, smoked Rainbow trout, whey proteins (I and II) and infqnt formulas (I and II) were determined. Available lysine contents of the samples, except for the dry mjllks that were stored four and twelve months, were determined. Protein quality of the samples was evaluated using Chemical Score (CS), Essential Amino Acid Index (EAAI), Modified Essential Amino Acid Index, FA0/WH0 Index, Amino Acid Score (AAS), Protein Digestibility Corrected Amino Acid Score (PDCAAS), Amino Acid Rating (AAR), Relative Amino Acid Rating (RAAR), Protein Digestibility Corrected AAR and RAAR (PDCAAR and PDCRAAR) Calculated-PER and Discriminate Calculated-PER methods. Biological PER, NPR, NU and FCE values of the reference protein casein were found to be 2.63, 4.16, 4.24 and 0.30, respectively. Chemical Scores of allthe samples were found to be lower than the egg protein. Modified Essential Amino Acid Index, on the other hand, was found to be a better indicator of amino acid composition. Available lysine content of dry milk (stored for 18 months) was significantly lower than the available lysine content of raw milk. Broiling and smoking caused significant losses in the available lysine content of the raw Rainbow trout, however broiling and smoking processes had similar effects. Since the production of commercial infant formulas (coded as formula I and II) involved heat treatment, a low availability of lysine was obtained. In vitro protein digestibility of all samples were determined using three different methods which highly correlated with each other. Sterilization of raw milk and processing of dry milk caused an increase, and storage of dry milk for 18 months caused a decrease protein digestibility. Amino Acid Scores of casein, raw milk, dry milk (0 month), dry milk stored for 6 months, raw Rainbow trout, broiled Rainbow trout, and smoked Rainbow trout were found to be 100 %, however Protein Digestibility Corrected Amino Acid Scores of only casein, raw milk and dry milk (0 month) were 100 %. Amino Acid Rating and Relative Amino Acid Rating, recommended for the evaluation of the protein quality of infant formulas were found to be within the given ranges for milk based formulas for formula I but were higher for the sucrose-sweetened formula II. Results with the in vitro digestibility corrected values were found to be in accordance with the literature. Further studies should be done on C-PER and DC-PER methods with a larger group of food protein sources.

Açıklama

Anahtar Kelimeler

Gıda Mühendisliği, Food Engineering, Hayvansal proteinler, Animal proteins, Isıl işlem, Heat treatment, Kazeinler, Caseins, Nem, Moisture, Protein oranı, Protein ratio, Proteinler, Proteins

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