86 Impact of steeping corn DDGS over 72 hours without or with fiber degrading enzymes and protease alone or in combination on concentration of sugars and organic acids and pH in the liquid medium

Abstract

Abstract We investigated the impact of steeping corn DDGS over 72 h with or without fiber degrading enzymes (FDE) and protease (PRO) on concentration of sugar, acetic and lactic acid, and pH. The concentration of crude fat, CP, NDF and ADF in DDGS sample was 8.6, 30.8, 36.1, 12.2% DM, respectively. Treatments were: 1) DDGS steeped without enzymes (Control), 2) DDGS steeped with FDE (FDE), 3) DDGS steeped with protease (PRO), 4) DDGS steeped with combination (FDEPRO). Enzymes were added at 1% of DDGS. Briefly, 50g of DDGS was mixed with 500-mL water with or without enzymes in sterile plastic bottles and steeped for 0, 12, 24, 48 and 72-h at 37℃ with continuous agitation. Samples were aliquoted to individual bottle for each timepoint. At each time point, bottles were pulled out from the incubator for pH measurements and liquid medium supernatant for sugars and acids. Highest arabinose, xylose and glucose was observed at 12 and 24 h, followed by decrease at 48 and 72 h. At 12 h, arabinose was higher (P < 0.05) for FDE and FDEPRO than control. The highest xylose and glucose was seen at 12 h for PRO, FDE and FDEPRO while control was highest at 24 h. Acetic acid and lactic acid increased over time. At 72 h, FEDPRO had highest acetic acid compared to control and PRO, while lactic acid was highest for FDE and FDPRO compared with (P < 0.0001) control and PRO. The pH decreased (P < 0.05) over time for all treatments. At 72 h, FDE had lowest pH followed by FDEPRO, PRO and control (P < .0001). Overall, arabinose, xylose and glucose increased to a certain timepoint and decreased, while lactic and acetic acid increased over time, subsequently leading to lowest pH at 72 h. In conclusion, FDE increased concentration of sugars and acids in steeped DDGS whereas PRO had no effect.