Quality index of oils extracted from gamma-irradiated peanuts (Arachis hypogaea L.) of the golden and bari varieties

Effect of thermal pretreatments on the quality attributes and irradiation markers of sesame oil extracted from sesame seeds without and with gamma irradiation

This study comparatively studied the effects of three thermal pretreatment methods, i.e., wet-heat (WT), roasting (RT) and microwave (MT), on the quality attributes and irradiation markers of sesame oil obtained from sesame seeds without and with gamma irradiation. Results showed that gamma irradiation had negligible effect on the quality of sesame seeds and their extracted oils. The effects of thermal pretreatments on irradiated and non-irradiated sesame seeds and their oils were similar, little synergistic effects were observed. The RT-treated oils had more carotenoids, chlorophyll, total phenols, tocopherols, and heterocyclic volatiles content, as well as longer oxidation induction time, but darker color compared with their WT- and MT-treated counterparts. All oil samples had identical FTIR spectra. Eight radiolytic hydrocarbons were identified in the irradiated sesame oils. Thermal pretreatments reduced the content of radiolytic hydrocarbons, but did not significantly change their composition. Our study helps to identify products from irradiated sesame seeds.

Shade of Innovative Food Processing Techniques: Potential Inducing Factors of Lipid Oxidation

With increasing environmental awareness and consumer demand for high-quality food products, industries are strongly required for technical innovations. The use of various emerging techniques in food processing indeed brings many economic and environmental benefits compared to conventional processes. However, lipid oxidation induced by some "innovative" processes is often "an inconvenient truth", which is scarcely mentioned in most studies but should not be ignored for the further improvement and optimization of existing processes. Lipid oxidation poses a risk to consumer health, as a result of the possible ingestion of secondary oxidation products. From this point of view, this review summarizes the advance of lipid oxidation mechanism studies and mainly discloses the shade of innovative food processing concerning lipid degradation. Sections involving a revisit of classic three-stage chain reaction, the advances of polar paradox and cut-off theories, and potential lipid oxidation factors from emerging techniques are described, which might help in developing more robust guidelines to ensure a good practice of these innovative food processing techniques in future.

Response of peanut (Arachis hypogaea L.) plant to bio-fertilizer and plant residues in sandy soil

Nitrogen (N) fertilizer has been intensively used to improve peanut productivity. However, the high cost of N fertilizer, and the need for sustainable alternative fertilizer sources have increased the strategic importance of nitrogen fixation (NF). Thus, field experiments were conducted in an experimental farm with a drip irrigation system, at the Atomic Energy Authority, Inshas, Egypt, in order to measure the impact of efficiency symbiotic Bradyrhizobium sp. and asymbiotic Azotobacter sp. on NF, from air and soil, in the presence or absence of plant residues on the growth and yield of peanut plant. All treatments received nitrogen fertilizer at a rate of 72 kg N per hectare. Nitrogen dose was applied using ammonium sulphate ¹⁵N labeled of 10% atom excess from the peanut. Results indicated that the application of Bradyrhizobium sp. with plant residues significantly increased fresh and dry weight/m², pod and seed weight/plant^-1,100- seed weight, and biological yield kg ha^-1, where the highest mean values of seed yield (4648 and 4529 kg ha^-1), oil % (52.29 and 52.21%), seed protein percentage (16.09 and 15.89%), as well as nitrogen derived from air (63.14 and 66.20%) in the first and second seasons were recorded under the application of Bradyrhizobium sp, respectively. Bradyrhizobium sp. inoculation showed nearly close portions of Ndfa to those recorded with Azotobacter sp., in both the presence and absence of plant residue application through the two seasons. The investigated yield signs and their properties were significantly enhanced by bacterial inoculation with plant residue application. The present study shows that both possibility of NF of peanut, and nitrogen uptake in the soil are enhanced by field inoculation with effective Bradyrhizobium sp. with plant residue application. In practice, inoculation is a great strategy to improve soil fertility for subsequent planting, since it helps boost the import of nitrogen from plant biomass into the soil.

Effect of Maturing Stages on Bioactive Properties, Fatty Acid Compositions, and Phenolic Compounds of Peanut (Arachis hypogaea L.) Kernels Harvested at Different Harvest Times

The present study investigated the effects of harvesting time on the physicochemical properties, antioxidant activity, fatty acid composition, and phenolic compounds of peanut kernels. The moisture content (air-dried basis) of peanut kernels was determined between 4.47% (September 15, 2019) and 7.93% (October 6, 2019), whereas the oil contents changed from 45.95% (October 6, 2019) to 49.25% (September 22, 2019). The total carotenoid, chlorophyll, and phenolic contents were low throughout the harvest, showing differences depending on the harvest time. Total phenolic content changed from 0.28 mg GAE/L (September 29, 2019) to 0.43 mg GAE/L (September 8, 2019), whereas the antioxidant activity varied from 4.42% (August 25, 2019) to 4.70% (September 1, 2019). The dominant fatty acids were palmitic, oleic, and linoleic acids, depending on the harvest time, followed by stearic, behenic, arachidic, and linolenic acids. The (+)-catechin content ranged from 2.17 mg/L (September 8, 2019) to 5.15 mg/L (September 1, 2019), whereas 1,2-dihydroxybenzene content changed between 2.67 mg/L (October 6, 2019) and 5.85 mg/L (September 29, 2019). The phenolic compound content fluctuated depending on the harvest time. The results showed that peanut kernel and oil had distinctive phenolic profiles and fatty acid contents. The findings of the present study may provide information for the best time to harvest peanut to achieve its maximum health benefits.

Impact of roasting conditions on the quality and acceptance of the peanut paste

Roasting is the main processing step performed to improve sensory and conservative properties of peanuts. The objective of this study was to evaluate changes in peanut oil and paste during roasting at different temperatures in a conventional oven (80, 110, 140, 170, and 200°C) and microwave. The increase in roasting temperature promoted reduction of L* value, b* value, and increases of a*, K₂₃₂ , K_270, and acidity. For alpha (α), gamma (γ), and delta (δ) tocopherols, as well as fatty acids, less degradation were observed at the roasting temperature of 140°C. Paste acceptability greater than 70% was achieved with roasting at 140°C. Based on the results, 140°C was the optimal roasting temperature that achieved the best paste acceptance rates with the smallest changes in oil and tocopherol quality parameters.

Effects of gamma irradiation on aflatoxin B1 levels in soybean and on the properties of soybean and soybean oil

Fungal infection is inevitable in the cultivation and storage process of soybean. Gamma irradiation is an effective method to control fungal growth and inactivate mycotoxins. The effects of gamma irradiation and fungal damage on the number of fungi, aflatoxin B1 content, proximate composition of soybeans, and quality of soybean oil (acid value, peroxide value, iodine value, fatty acid profile, tocopherols content, and oxidation stability) were investigated in this work. Growth of fungi caused some changes in proximate composition of soybean and qualities of soybean oil. However, the changes depended on the damage extent of soybeans. No significant change was found for the soybeans incubated for 30 days (moderately fungi-damaged). Gamma irradiation could completely eliminate the fungi and greatly reduce the content of aflatoxin B1 in soybeans at 10 kGy. For soybeans incubated for 30 days, there were no significant changes in the quality attributes, tocopherols content and oxidation stability of oil when the gamma irradiation dose was less than 20 kGy. Gamma irradiation is a promising method to improve the safety and economy of moderately fungi-damaged soybean used for feedstuff.

Effect of heating on oxidation stability and fatty acid composition of microwave roasted groundnut seed oil

The oxidative stability and fatty acid composition of groundnut seed oil (GSO) exposed to microwaves were evaluated during heating at 170 °C. During heating, the oxidative indices such as free fatty acid, peroxide value, p-anisidine value, TOTOX, thiobarbituric acid value, specific extinctions, and color value were increased. The increments were found to be higher in unroasted seed oils compared to roasted ones indicating lower release of lipid oxidation products in roasted GSO. After 9 h heating, the relative content of polyunsaturated fatty acid (PUFA) decreased to 89.53% and that of saturated fatty acid (SFA) increased to 117.46% in unroasted sample. The relative content of PUFA decreased to 92.05% and that of SFA increased to 105.76% in 7.5 min roasted sample after 9 h of heating. However, the roasting process slowed down the oxidative deterioration of PUFA. With increased heating times, an appreciable loss was more apparent in the triacylglycerol species OLL and OOL in unroasted samples compared to roasted ones. In FTIR, the peak intensities in unroasted samples were markedly changed in comparison with roasted samples during heating. The roasting of groundnut seed prior to the oil extraction reduced the oxidative degradation of oil samples; thereby increasing heat stability.

Impact of electron beam irradiation on quality of sea buckthorn (Hippophae rhamnoides L.) oil

BACKGROUND

Sea buckthorn oil is a valuable product that can be incorporated into daily foodstuffs, cosmetics or pharmaceuticals. The effect of accelerated electron irradiation up to 8 kGy on quality characteristics of sea buckthorn oil was investigated in this study.

RESULTS

Irradiation had no significant influence on phenolic content. Conversely, carotenoid content, antioxidant activity, and oxidative status suffered alterations as the irradiation dose increased. Although no colour changes were visible for oil irradiated up to 3 kGy, the total colour difference indicated clearly changes that involved a two-step pattern associated with slow degradation of oil colour up to 3 kGy, followed by a fast degradation up to 8 kGy. Some changes of the oil spectral features related to the frequency and intensity of some bands have been found after irradiation, indicating an alteration of the structural integrity induced by irradiation.

CONCLUSION

The present investigation may be a useful starting point for irradiation processing of food or non-food matrices containing sea buckthorn oil. Thus, sea buckthorn oil safety can be ensured with minimal undesirable changes in its quality by applying irradiation doses up to 3 kGy, which allow control of the microbial contamination depending on microorganism type and initial microbial load.

Gamma radiation induced oxidation and tocopherols decrease in in-shell, peeled and blanched peanuts

In-shell, peeled and blanched peanut samples were characterized in relation to proximate composition and fatty acid profile. No difference was found in relation to its proximate composition. The three major fatty acids were palmitic acid, oleic acid, and linoleic acid. In order to investigate irradiation and storage effects, peanut samples were submitted to doses of 0.0, 5.0, 7.5 or 10.0 kGy, stored for six months at room temperature and monitored every three months. Peanuts responded differently to irradiation, particularly with regards to tocopherol contents, primary and secondary oxidation products and oil stability index. Induction periods and tocopherol contents were negatively correlated with irradiation doses and decreased moderately during storage. α-Tocopherol was the most gamma radiation sensitive and peeled samples were the most affected. A positive correlation was found among tocopherol contents and the induction period of the oils extracted from irradiated samples. Gamma radiation and storage time increased oxidation compounds production. If gamma radiation is considered an alternative for industrial scale peanut conservation, in-shell samples are the best feedstock. For the best of our knowledge this is the first article with such results; this way it may be helpful as basis for future studies on gamma radiation of in-shell crops.