Publication: Peynir altı suyundaki süt proteinlerinin ayrıştırılması ve antioksidan etkilerinin incelenmesi
Abstract
Süt ana besin unsurlarını, vitaminler ile eser elementleri ve bazı enzimleri içeren bir sıvı besindir. Yapısında annenin bağışıklık sisteminin elemanlarını da içerdiğinden, yenidoğanı enfeksiyonlara karşı pasif olarak korumaktadır. Kesilmiş sütün sıvı kısmı olan süt serumu (whey) ise çözünür halde bulunan beta-laktoglobulin, alfa-laktalbumin, albumin ve immünglobulinlerden oluşan bir protein karışımıdır. Son yıllarda sütün tedavi edici etkisi yüksek bir besin olduğu gözlenmiştir. Bu etki daha çok süt serumu proteinlerine bağlanmaktadır ve bu proteinlerin serbest radikal hasarına karşı belirgin koruyucu etkileri olduğu ileri sürülmüştür. Örneğin, antioksidan olarak nitelenen whey protein konsantreleri HIV enfeksiyonlu hastalarda ve değişik kanser olgularının tedavisinde olumlu etkiler yaratmıştır. Peynir yapımı sırasında sütten ayrılan ve peynir altı suyu olarak adlandırılan süt fraksiyonunun süt serumu proteinlerince zengin olduğu bilinmektedir. Bu yan ürün gıda endüstrisinde toz haline getirilerek kullanılmaktadır. Çalışmamızda peynir altı suyu tozundaki (PAST) süt proteinlerinin kromatografik yöntemlerle ayrılmasından sonra elde edilen fraksiyonların antioksidan etkileri incelendi ve bu etkiye sülfidril gruplarının katkısı araştırıldı. Sephadex G-200 kromatografisiyle üç ana süt serumu proteini (BSA, a-laktalbumin ve b-laktoglobulin) elde edildi. PAST'nun ve fraksiyonların antioksidan aktiviteleri incelendiğinde fraksiyonlardan 1 ve 2'nin yüksek aktivite içerdikleri sülfidril gruplarıyla paralel olarak belirlendi. Tek başına PAST'nun antioksidan aktivitesinin fraksiyonlardan daha düşük olduğu, en fazla antioksidan aktivitenin fraksiyon 1'de olduğu görüldü. PAST proteinleri pepsin ile proteoliz edildiğinde fraksiyon 3'ün antioksidan aktivitesinin arttığı belirlendi. Bu artışın fraksiyon 1 ve 2'den uzaklaşan küçük peptidlerle ilişkili olabileceği düşünüldü.
SEPARATION OF MILK PROTEINS IN WHEY POWDER AND ANALYSIS OF THEIR ANTIOXIDANT EFFECTS Milk is a liquid nutrient which contains main nutritional ingredients, vitamins, essential elements and some enzymes. It contains molecules of the mother's immune system and thus passively protects the newborn from infections. Milk serum (whey ) is the liquid part of the curd and is a mixture of proteins containing beta-lactoglobulin, alpha-lactalbumin, albumin and immunoglobulin. In recent years, it has been observed that milk has therapeutic properties. This effect is mostly related to milk serum proteins and their protective effects on free radical damage. For instance, whey protein concentrates with antioxidant effects had positive effects on patients with HIV infections and different cancers. Whey is a product of cheese manufacture and is rich in milk serum proteins. This side product is powdered and used in the nutritional industry. In this study the antioxidant effects of fractions obtained from the chromatographic separation of milk proteins in whey powder were examined and the contribution of sulphydryl groups to this effect was analyzed. Three main milk proteins (BSA, a-lactalbumin and b-lactoglobulin) were obtained with Sephadex G-200 column chromatography. When the antioxidant activities of whey powder and its chromatographic fractions were examined it was observed that the first and second fractions had high activity paralleled with sulphydryl groups. It was found that the antioxidant activity of whey powder was less than the fractions and that the antioxidant activity was highest fraction 1. When whey powder proteins were hydrolyzed with pepsin it was observed that the antioxidant activity of fraction 3 increased. It is thought that this increase is related to smaller peptides coming from fraction 1 and 2.
SEPARATION OF MILK PROTEINS IN WHEY POWDER AND ANALYSIS OF THEIR ANTIOXIDANT EFFECTS Milk is a liquid nutrient which contains main nutritional ingredients, vitamins, essential elements and some enzymes. It contains molecules of the mother's immune system and thus passively protects the newborn from infections. Milk serum (whey ) is the liquid part of the curd and is a mixture of proteins containing beta-lactoglobulin, alpha-lactalbumin, albumin and immunoglobulin. In recent years, it has been observed that milk has therapeutic properties. This effect is mostly related to milk serum proteins and their protective effects on free radical damage. For instance, whey protein concentrates with antioxidant effects had positive effects on patients with HIV infections and different cancers. Whey is a product of cheese manufacture and is rich in milk serum proteins. This side product is powdered and used in the nutritional industry. In this study the antioxidant effects of fractions obtained from the chromatographic separation of milk proteins in whey powder were examined and the contribution of sulphydryl groups to this effect was analyzed. Three main milk proteins (BSA, a-lactalbumin and b-lactoglobulin) were obtained with Sephadex G-200 column chromatography. When the antioxidant activities of whey powder and its chromatographic fractions were examined it was observed that the first and second fractions had high activity paralleled with sulphydryl groups. It was found that the antioxidant activity of whey powder was less than the fractions and that the antioxidant activity was highest fraction 1. When whey powder proteins were hydrolyzed with pepsin it was observed that the antioxidant activity of fraction 3 increased. It is thought that this increase is related to smaller peptides coming from fraction 1 and 2.