Peanut Flour: Lipid Oxidation Mechanism And Its Modeling Of Shelf Life

Peanut powder is major by-product in peanut oil production, and oxidative deterioration is the key factor of peanut powder shelf-life. As a new food ingredients, peanut flour lack of appropriate quality control measures. Quality evaluation, accelerated shelf life testand other related issues were studied in this paper. Quality assessment includes sensory evaluation, oil extraction of peanut powder, key flavor volatilesidentification and flavor volatilesevaluation. Schaal oven test is most common methods in shelf life accelerated test, and temperature and humidity were selected as acceleration factors in Schaal oven test of this paper. The kinetic equation under different accelerated factors was fitted and finally established a reasonable shelf-life prediction model.In addition, the test conditions and the relationship between temperature and induction period of peanut powder by OxipresTM oxygen bomb instrumentation was determined.In this paper, the accuracy and precision of oil extraction wereexamined by peroxide value, and the oil extractionprocedure: 100 gram peanut powder was weighted out, and added with n-Hexane(peanut powder/hexane, m: v=1:2.5) and 3 milliliter 2% TBHQ/ethyl ether. They were totally mixed and set aside for 30 min; then the solid part was remove by vacuum filter and the filtered fluid was evaporated by rotary evaporation apparatus with water bath at 50℃. The result indicated the best reproducibility compared with the classic iodometric titration method. When PVs were between 3.98mmol/kg and 19.26mmol/kg, the coefficient of determination reached 0.9994. The average In addition, recoveries were 95.66~100.03% with RSDs of 0.35~4.00%. All these features, the rapidity, low cost, as well as the analysis with no need of any special instrumentation, make it suitable as a routine method for the evaluation of the quality of peanut powder.To explore the relationship between flavor volatiles and flavor fade in peanut powder during storage, instrument analysis and sensory evaluation were applied in this paper. Flavor fade instrumental judgment in roasted peanut powder requires an understanding of the primary contributors to the negative flavor components involved in rancid peanuty odor. Initial flavor characteristics of roasted peanut powder over storage were explored by the sensory evaluation and chemical analyses, which GC-O and OAV(Odor Activity Value) was used to identify the aroma active compounds and further quantified by HS-SPME-GC-MS. At the same time,peroxide value during oxidation process in storage were studied. The relationship between aroma active compounds and sensory index was build up by PLSR model. The peroxide values and sensory analysis correlated directly with the amount of acetic acid(p<0.05), however, there was no significant correlation(p>0.05) between the nonanal, peroxide values, and the sensory analysis. The amount of ethyl acetate and D-limonene positively contribute to the freshness of the roasted peanutty flavor. This research does prove that the main cause of flavor deterioration is due to the lipid oxidation.In addition, prediction peroxide value using the OAV of aroma active compounds by partial least squares and definition the predicted peroxide value as flavor oxidation value.Schaal oven test andMikrolab OxipresTMoxygen bomb instrumentation were used for accelerated shelf life testin this paper. The effects of temperature and humidity on the peanut powder oxidation wereinvestigated withSchaal oven test.Measuring the corresponding index to explore the correlation between the factors showed that temperature affect the rate ofoxidation. The shelf life prediction modals based on oxidation under the accelerated factors temperature and humiditywere derived.Determination of the oxidative stability of peanut powder by Mikrolab OxipresTMoxygen bomb instrumentation, and the conditions: the sample size for the flasks 1/3 to 2/5, the temperature should not exceed 110℃, pressure 0.5MPa. The induction period prediction modals based on oxidation under the accelerated factors temperaturewas derived.