Antioxidants reduce lipid peroxidation of dried distillers grains with solubles (DDGS) and distillers corn oil (DCO) stored under high temperature and humidity conditions

Abstract Text:

This experiment was conducted to evaluate lipid peroxidation in reduced oil DDGS (RO-DDGS; 5.0 % ether extract, EE), high oil DDGS (HO-DDGS; 13.0 % EE), and 2 sources of DCO (DCO-1, 1.2, 0.08, and 0.48% moisture, impurities, and unsaponifiables [MIU]; and DCO-2, 1.2, 0.01, and 0.1% MIU). One lot of each ingredient was divided into 18 samples (~908 g for DDGS or 2 kg of DCO). Six samples of each ingredient were mixed with either no supplemental antioxidants (CON), Rendox-CQ^® (REN; 1,000 mg/kg EE; Kemin, Industries, Des Moines, IA), or Santoquin-Q4T^® (SAN; 1,500 mg/kg EE; Novus Intl., St. Louis, MO). Each mixture (n = 72) was split into thirds, and 1 portion was immediately frozen at -20°C (d 0). Two portions were stored under hot (38.6 ± 0.1°C) and humid conditions (94.0 ± 0.3%) for 14 or 28 d. The MIXED procedure of SAS was used to evaluate the effects of ingredient, antioxidant, storage time, and interactions, with d 0 values used as a covariate. Storage for 14 and 28 d, increased the peroxide value (PV), p-anisidine value (AnV), and thiobarbituric acid reactive substances (TBARS) of DCO and DDGS by 3 to 4 fold (P < 0.05). Over the entire storage period, PV of DCO-1 and HO-DDGS (12.3 and 12.6 ± 0.3 meq O₂/kg oil, respectively) exceeded (P < 0.05) that of DCO-2 and RO-DDGS (9.6 and 9.3 ± 0.3 meq O₂/kg oil, respectively). Adding REN or SAN (P < 0.05) reduced TBARS and AnV relative to CON (TBARS = 11.0 ± 0.2 mg malondialdehyde eq/kg oil and AnV = 6.5 ± 0.2) over the entire period (mean of d 14 and 28), but TBARS and AnV did not differ (P > 0.05) between antioxidants (TBARS = 6.1, and 5.9 ± 0.2 mg malondialdehyde eq/kg oil and AnV = 1.9 and 1.8 ± 0.2, for REN and SAN, respectively). The PV on d 14, 28, and overall was less (P < 0.05) with either antioxidant relative to CON (16.0 meq O₂/kg), but PV of ingredients with SAN exceeded (P < 0.05) REN (8.8 and 8.0 ± 0.2 meq O₂/kg oil for SAN and REN, respectively). In summary, antioxidants reduced peroxidation of DDGS and DCO by approximately 50% during 28 d of storage at 38.6 °C and 94.0% relative humidity, but neither antioxidant completely stabilized the ingredients. 

Keywords:

antioxidant, distillers corn oil, dried distillers grains with solubles