| Freeze-dried ethanol-water extracts of hulls, brans, peels or whole seeds of selected North Dakota crops (6 varieties of potato, 2 varieties of wheat, 3 varieties of edible beans, barley, oat and sunflower) were evaluated for antioxidant activity by the Active Oxygen Method (AOM) procedure, using soy oil as the substrate. After 9 hr. under AOM conditions, peroxide value (PV) determinations showed that navy bean hull extract with a PV of 15 had the strongest activity when compared with the control sample that attained a PV and 129 meq/kg. partial chemical analyses of the navy bean hull extract showed that it was composed of (1) moisture (4.12%), (2) protein (13.71%), (3) ash (4.78%), and (4) total dietary fiber (1.35%). Amino acid analysis indicated that glutamic acid was the major amino acid. Potassium was the most abundant element. Reversed-phase high-performance liquid chromatography (HPLC) of the extract revealed the presence of 9 free phenolic acids: gallic, gentistic, caffeic, protocatechuic, syringic, salicylic, p-hydroxybenoic, vanillic and p-coumaric acids. Protocatechuic acid was the major phenolic acid (49%). The free phenolic acids accounted for 0.2% of the total weight of the extract. Food application studies of the navy bean hull extract in (1) oils (soy and sunflower), (2) ground beef, and (3) ground fish were conducted to investigate the effectiveness of the extract as an antioxidant. Results showed that 100 parts per million of navy bean hull extract was a stronger antioxidant in soy and sunflower oils and ground beef than the synergistic effect observed with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) and Rosemary-AR, but was less effective than tertiary butyl hydroquinone (TBHQ) in those food systems. However, navy bean hull extract (at the concentrations incorporated) was not effective in preventing the development of oxidative rancidity in ground fillets of mackerel fish. Microbiological studies indicated that the navy bean hull extract was not effective in preventing bacterial growth in ground beef and ground fish at the concentrations investigated. Generally, results indicated that navy bean hull extract could be an effective antioxidant in vegetable oils and beef products. |
