The influence of cryogenic grinding on the particle size of proso millet brans determined by laser diffraction particle sizing

Posije prosa su visokovrijedan nusproizvod sa velikom nutritivnom vrijednošću i zdravstvenim potencijalom, posebno za osobe oboljele od celijakije. Bogate su različitim bioaktivnim spojevima. Primijećeno je kako smanjenje veličine čestica posija prosa povećava bioraspoloživost određenih bioaktivnih spojeva. Dodatno, primjena netoplinskih tretmana prilikom usitnjavanja žitarica može očuvati aktivnost bioaktivnih spojeva. Cilj ovog rada bio je ispitati utjecaj kriogenog mljevenja na veličinu čestica posija prosa. Posije prosa samljevene su na kugličnom mlinu pri sobnoj temperaturi i pri temperaturi od -196°C (kriogeno hlađenje) u trajanju od 2, 4, 8, i 12 minuta, a potom im je veličina čestica određena metodom laserske difrakcije (mokrom i suhom disperzijom). Na temelju rezultata zaključeno je kako kriogeno mljevenje uzrokuje brže i veće smanjenje veličine čestica posija prosa od mljevenja pri sobnoj temperaturi te da je za mjerenje veličine čestica pogodnija primjena suhe disperzije.Proso millet bran is a high valuable by-product with high nutritional value and health potential, especially for people with celiac disease. They are rich in various bioactive compounds. It was noticed that reduction of bran particle size increases bioavailability of specific bioactive compounds. Also, the application of non-thermal treatments during the grain milling can preserve the activity of bioactive compounds. The aim of this study was to investigate the effect of cryogenic grinding on proso millet bran particle size. Proso millet bran was ground using a ball mill at a room temperature and at a temperature of -196°C (cryogenic cooling) for 2, 4, 8 and 12 minutes and after that, the bran particle size was determined by laser diffraction method (using wet and dry dispersion). Based on the results it was concluded that cryogenic grinding causes a faster and greater reduction of proso millet bran than does the grinding at room temperature and that for measuring the proso millet bran particle size it is more appropriate to use dry dispersion method