Effect of various acids and sulfites in steep solution on yields and composition of corn fiber and corn fiber oil

The addition of six acids (organic and inorganic) and four sulfite compound s (including gaseous SO2) during the conventional corn wet-milling steeping process of two yellow dent corn hybrids were evaluated for the effect on c orn fiber yield, corn fiber oil yield, and the composition of three phytost erol compounds (ferulate phytosterol esters [FPE], free phytosterols [St], and phytosterol fatty acyl eaters [St:EI) in the corn fiber oil. No signifi cant effect of different sulfite compounds and acids were observed on corn fiber yields. However, a significant effect was observed on corn fiber oil yield and the composition of corn fiber oil for phytosterol compounds. Thre e of the sulfite compounds (including gaseous SO2) caused very little effec t on the levels of phytosterol compounds compared with the control sample ( corn steeped with sodium metabisulfite and lactic acid). However, for one h ybrid, ammonium sulfite gave a significantly higher yield of FPE and St:E a nd had no effect on the yield of St. For the other hybrid, it gave a signif icantly higher yield of FPE and had no effect on the yield of St and St:E c ompared with the control sample. This indicates that the effect of these su lfite compounds on yields of these phytosterol compounds in corn fiber oil is probably hybrid-dependent. No significant effect of acids was observed o n corn fiber yields, but significant effects were observed on corn fiber oi l yields and yields of phytosterol compounds in the corn fiber oil. The eff ect also seems to be hybrid-dependent because different acids affected the two hybrids differently. Overall, it seems that weak acids have a positive effect on increasing the individual phytosterol compounds in the corn fiber . When comparing the effect of experimental acids and sulfites on the two h ybrids, acids have a more positive effect than sulfites in increasing the y ield of phytosterol compounds in corn fiber oil.