Content of soluble proteins and available lysine in soybean products

Abstract

Soybean grain of cultivars Bosa and ZPS 015 was used in the experiment. The contents of available lysine, as well as, water and salt soluble proteins were analyzed in fresh soybean grain, soybean products made after the process of dry extrusion, micronisation, microwave toasting and autoclaving. The content of soluble proteins decreased under the influence of higher temperatures in the course of all treatments of processing. The drop of solubility was already drastically manifested at the temperature of 100oC during dry extrusion, while it decreased gradually over other treatments. The processes of micronisation and microwave toasting showed the greatest effect on the reduction of lysine availability. Dry extrusion and autoclaving, proceeding within closed systems in which the increased moisture content has a special effect, resulted in significantly smaller changes of the available lysine content.

Za istraživanje je odabrano zrno soje sorata Bosa i ZPS 015. Analiziran je sadržaj iskoristivog lizina, kao i proteina rastvorljivih u vodi i rastvorima soli u sirovom sojinom zrnu, sojinim proizvodima, dobijenim nakon procesa suve ekstruzije, mikronizacije, mikrotolasnog prženja i autoklaviranja. Pod uticajem povišene temperature tokom svih primenjenih tretmanima prerade došlo je do snižavanja sadržaja rastvorljivih proteina. Pad rastvorljivosti se drastično manifestovao već na temperaturi od 100oC tokom suve ekstruzije, dok je kod ostalih tretmana, sa povećanjem temperature došlo do postepenog snižavanja rastvorljivosti. Najveći uticaj na sniženje iskoristljivosti lizina imao je proces mikronizacije i mikrotalasnog prženja. Suva ekstruzija i autoklaviranje, koji se odvijaju u zatvorenim sistemima u kojima povećan sadržaj vlage ima poseban efekat, uslovili su znatno manje promene sadržaja iskoristivog lizina.