The effect of autoclaving on soluble protein composition and trypsin inhibitor activity of cracked soybeans

Abstract

The effects of autoclaving conditions (heating for 5, 10 and 15 minutes at 0.5 bars over pressure) and oil-extracting temperatures (40°C, 60°C) on protein content, composition, and inhibitor activity of cracked soybeans were investigated. The results obtained indicated that oil-extracting method and heat treatment had significant influence on soluble protein content and composition. Raw soybean samples defatted at lower temperature had better solubility (535.42±2.10 mg/g) than those obtained by the Soxhlet procedure (345.53±2.80). The same results were obtained for nitrogen solubility index. Autoclaving combined with two oil-extraction methods decreased protein solubility to 180.32±1.50 -245.41±1.41 mg/g, while the dominant component of heat treated flours was 11S fraction. High content of glycinin fraction (44.59-41.10%) implies the possible use of treated samples in food industry. Residual activity of treated samples was 43.40-84.26%. Kunitz inhibitor (KTI) was responsible for residual inhibitor activity.

Ispitivan je uticaj termičke obrade lomljenog zrna u autoklavu pri nadpritisku od 0.5 bara i temperaturi od 96°C u toku 5, 10 i 15 minuta, kao i efekat ekstrakcije ulja pri temperaturama od 40 i 60°C na sadržaj i sastav rastvorljivih proteina i tripsin inhbitorsku aktivnost. Dobijeni rezultati ukazuju da ovi tretmani imaju značajan uticaj na sadržaj i sastav rastvorljivih proteina. Netretirani uzorci odmašćeni pri nižim temperaturama karakterišu se većim sadržajem rastvorljivih proteina od uzoraka odmašćenih pri 60°C. Tretman u autoklavu kombinovan sa dva različita postupka ekstrakcije ulja redukuje sadržaj proteina rastvorljivih u puferu pH 8.0 do 180.32±1.50 -245.41±1.41 mg/g. Rezervni proteini soje ispoljili su različitu stabilnost tokom obrade. Najosetljivijim su se pokazale komponente 7S frakcije. Rezidualna inhibitorska aktivnost tretiranih uzoraka je 43.40-84.26%, pri čemu je KTI okarakterisan kao nosilac te aktivnosti.