In recent years, studies of the antioxidant capacity of foods has been actively pursued, with the antioxidant activity of various food components being reported. Many methods have been developed to evaluate antioxidant activity, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, superoxide dismutase (SOD) activity, and oxygen radical absorbance activity (ORAC). The DPPH radical-scavenging method measures radical removal, producing a characteristic change to colorlessness in the assay upon conversion to the DPPH radical, which is a stable organic radical. SOD is an enzyme that was discovered by McCord and Fridovich, and is a superoxide radical (O2·-) scavenger that is component of the endogenous antioxidant system. SOD catalyzes the conversion of superoxide to either hydrogen peroxide (H2O2) or oxygen (O2), and is used to measure antioxidant ingredients exhibiting SOD-like activity. Implementation is simple and easy, and these methods are widely used for the evaluation of antioxidant activity. The ORAC method was developed in 1992 by Cao et al. at the U.S. National Institute of Aging. The assay uses fluorescein as a fluorescent probe to measure antioxidant activity in the presence of underlying reactive oxygen generation. The fluorescent intensity of fluorescein degrades over time in the presence of reactive oxygen, which is used to measure antioxidant activity as an index. Because the ORAC assay relies on generated peroxy radicals, the classification of fixed quantities of hydrophilic and lipophilic antioxidant materials is possible and is correlated with in vivo effects. Additional merits of the ORAC assay include the ability to assess antioxidant activity using a chemical reaction that is relatively simple, easily operated, and does not require specialized apparatus. However, the presence of compounds with antioxidant activity greatly influences the ORAC assay, and a potential drawback of the assay is that its results may not reflect antioxidant activity in vivo. In this study, chemical analyses (DPPH radical removal activity, SOD assay copper ion reduction) and the cellular antioxidant stress response, measured using a luciferase reporter assay of antioxidant response element induction through the Keap-1/Nrf2 pathway, was used to more accurately reflect in vivo conditions in evaluating antioxidant activity. The possibility that food components exhibit various antioxidant activities was evaluated using multiple assay systems.
This study aimed to evaluate both the lipophilic and hydrophilic oxygen radical absorbance capacities (ORAC) in pressed oils made from sesame (Sesamum indicum L.) cultivar “Maruhime” and rapeseed (Brassica napus L.) cultivar “Nanaharuka.” For this reason, we slightly modified the extraction method for antioxidant compounds using an accelerated solvent extractor system, and the multi-laboratory validated lipophilic ORAC method previously reported. Acceptable recovery was observed when four matrices of oils and fats fortified with α-tocopherol and gallic acid were subjected to the modified extraction method. Moreover, it was confirmed that the lipophilic ORAC value of α-tocopherol, as determined by the modified method, was within the range of the mean±reproducibility standard deviation in the multi-laboratory comparison study. In the pressed oil from sesame cultivar “Maruhime,” L-ORAC value was 12.6 to 33.8 times higher than H-ORAC, and the mean L-ORAC and H-ORAC values were 2926 and 130μmol-Trolox equivalent/100g, respectively. Also, L-ORAC value in the pressed oil from rapeseed cultivar “Nanaharuka” was 2.2 to 13.1 times higher than H-ORAC, and the mean L-ORAC and H-ORAC values were 552 and 87μmol-Trolox equivalent/100g, respectively. The contribution of tocopherols to L-ORAC value of the pressed oil from rapeseed cultivar “Nanaharuka” ranged from 24 to 55%; however, the contribution was smaller, ranging from 7 to 22%, in the pressed oil from sesame cultivar “Maruhime.”
We evaluated the effects of a microwave concentration process on the nutrition and taste of tomato puree as well as the energy consumption of the process. The development of a novel concentration method to produce high quality tomato puree was discussed. The residual ratio of lycopene and L-ascorbic acid in tomato puree concentrated by vacuum microwave was greater than that by other methods (conventional heating or normal microwave concentration). High temperature treatment during normal microwave treatment affected the taste of tomato puree. Energy consumption of normal microwave concentration was the lowest of all processes. We concluded that normal microwave concentration of tomato puree was suitable for producing palatable puree and reducing energy consumption.
Emu meat is distributed as a healthy foodstuff in the United States and Australia; however, its processing properties remain unclear. This study aimed to reveal the chemical and processing properties of emu meat for the manufacturing of frankfurter sausages. Compared to pork thigh meat, emu thigh meat showed higher protein content and significantly lower fat and cholesterol content. Also, emu thigh meat contained six-fold higher iron content than pork thigh meat. The addition of salt to minced emu thigh meat produced a paste with higher gel strength and lower extraction of salt-soluble proteins than that of pork thigh meat. The color of emu meat paste, developed using a color-producing reagent, was more stable against heat treatment than that of pork meat. Based on these results, we successfully developed emu meat frankfurter sausages using an optimized process. The sausage was characterized by high protein and iron contents and low fat, salt and calories as well as good physical properties and coloration.
Rice gel is an intermediate material obtained by high-speed shearing of high amylose gelatinized rice. Rice gel exhibits a high affinity with oil, and thus it acts as a physical property improver, a thickener, and an emulsifier when added to oil and sheared at high speed. The emulsified rice gel suppresses not only changes in E* (hardness) but also changes in tan δ (gel texture) during storage as compared to rice gel without added oil. For this reason, the emulsified rice gel is an effective option when distributed and used as an intermediate material in various industries. Emulsified rice gel can be expected to be used in the development of various products such as meat products, iced confections, dressings, breads and fillings.
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