Temperature dependence of the autoxidation and antioxidants of soybean, sunflower, and olive oil

Oxidative Stability of Cottonseed Butter Products under Accelerated Storage Conditions

Cottonseed is a natural product of cotton (Gossypium spp.) crops. This work evaluated the oxidative stability of cottonseed butters through accelerated autoxidation by storage at 60 °C for 25 days. Three oxidative stability parameter values (peroxide value, p-anisidine value, and total oxidation value) were monitored over the storage time. These chemical measurements revealed that the storage stability of the butter products was dominated by primary oxidation of lipid (oil) components, while the secondary oxidation levels were relatively unchanged over the storage time. An analysis of the tocopherols (natural oxidants in cottonseed) suggested not only the protection function of the molecules against oxidation of the cottonseed butter during storage, but also the dynamic mechanism against the primary oxidation of lipid components. Attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR) data confirmed no changes in the major C functional groups of cottonseed butters over the storage time. On the other hand, characteristic minor peaks of conjugated dienes and trienes related to lipid oxidation were impacted by the accelerated storage. As each day of accelerated oxidation at 60 °C is equivalent to 16 days of storage at 20 °C, observations in this work should have reflected the oxidative stability behaviors of the cottonseed butters after about 13 months of shelf storage under ambient storage conditions. Thus, these data that were collected under the accelerated oxidation testing would be useful not only to create a better understanding of the autooxidation mechanism of lipid molecules in cottonseed butters, but also in developing or recommending appropriate storage conditions for cottonseed end products to prevent them from quality degradation.

Influence of hot air drying on capsaicinoids, phenolics, flavonoids and antioxidant activities of 'Super Hot' chilies

Hot air drying is an alternative technique to either maintain or increase bioactive compounds in agricultural products because temperatures can be controlled. The effects of different hot air oven drying temperatures and times on the physicochemical changes, bioactive compounds (capsaicinoids, phenolic and flavonoid profiles and contents) and antioxidant activities in dried 'Super Hot' chili fruits were evaluated. The chilies were dried in a hot air oven at low (60-100 °C) or high (120-160 °C) temperatures for 30, 60, 120 min and at 12-13% moisture content (MC). The main compounds presented in chili fruits were capsaicinoids, limonene, pinene, tocopherol and oleic acid, regardless of drying temperature and time. Although the total flavonoid contents decreased during the drying process, the total phenolic contents increased (38-51%), and capsaicinoids, the primary pungent compounds, increased six-times at 120-160 °C compared to the fresh chilies. The phenolic profiles showed that chlorogenic acid was the most stable and abundant amongst the nine quantified phenolic compounds. In the flavonoid profile, both rutin and quercetin can be detected at a high temperature of 160 °C, with a decreasing trend. The main pungent compounds, capsaicin and dihydrocapsaicin, were found to increase compared to the fresh chilies, especially at 12-13% wet basis (w.b.). Although the antioxidant activities (ABTS• + and DPPH•) of dried chilies at all temperatures decreased with increasing drying time, these activities were still detected. Therefore, drying chilies at 160 °C (120 min) can not only maintain the capsaicinoids, phenolics and flavonoids that can be utilized by the pharmaceutical and food industry, but can also reduce the production time.

Phenolic compounds from virgin olive oil obtained by natural deep eutectic solvent (NADES): effect of the extraction and recovery conditions

Environmentally friendly natural deep eutectic solvents (NADES) have been shown to efficiently extract a wide range of phenolic compounds from virgin olive oil (VOO). The objective of this work was to optimize the yield of olive oil phenols extracted by NADES based on xylitol/choline choride (Xyl/ChCl). Different extraction and recovery conditions were investigated, including the effect of different extraction operating parameters (temperature, time, VOO:NADES ratio) and subsequent recovery conditions (XAD resin height, wash-water and eluent volume and pH). The highest concentration of phenols (555.36 mg/kg VOO) was obtained from extraction at 40 °C for 1 h, with a 1:1 ratio, using an adsorption resin XAD-16 with bed height of 10 cm, 250 mL acidified wash-water and 300 mL EtOH 100% as eluent. No statistically significant loss of the sum of phenolic compounds was observed when compared with the concentration values obtained by direct analysis in HPLC without the elimination of NADES. Additionally, a sequential desorption with different concentration of ethanol was used to determine the effect of the solvent concentration on polyphenol yield. Polar compounds, such as hydroxytyrosol and tyrosol, were recovered at 81.7% and 83.6%, respectively with 50 and 80% ethanol; however, 100% ethanol was required for the complete elution of oleacein (3,4-DHPEA-EDA) and oleocanthal (p-HPEA-EDA). In this paper we present an effective process for the extraction of polyphenols from VOO by NADES for direct analysis in HPLC and for the recovery and concentration of polyphenols by removing the solvent (NADES) with no losses of yield and solvent recycling.

Impact of Pleurotus ostreatus β-Glucans on Oxidative Stability of Active Compounds Encapsulated in Powders during Storage and In Vitro Digestion

Polyunsaturated fatty acids and α-tocopherol were encapsulated in powders by spray drying using maltodextrins DE 12 as wall material and different emulsifiers (Tween®20, acacia gum or β-glucans-rich extracts from Pleurotus ostreatus). The aim was to study the effects of the surfactants on: (a) the oil droplet size distribution and α-tocopherol stability during in vitro digestion, and (b) the oxidative stability during 15 days of accelerated storage. Acacia gum sample had the most stable particle size distribution up to the gastric phase, but showed a significant α-tocopherol degradation prior to the intestinal stage. On the contrary, β-glucan-samples displayed a bimodal distribution in the oral and gastric phases but retained α-tocopherol up to the beginning of the intestinal stage. At the end of intestinal stage, no α-tocopherol was found in the samples. The storage study showed that β-glucans improved the oxidative stability of the powders, which displayed 82% α-tocopherol retention after 5 days under accelerated conditions (60 °C), corresponding to 310 days at 20 °C, while acacia gum and Tween® 20 did not delay α-tocopherol degradation. Results highlight the potential antioxidant activity of β-glucans used as emulsifying agents during in vitro digestion and accelerated aging conditions.

Antioxidant Properties of Soybean Oil Supplemented with Ginger and Turmeric Powders

Soybean oil has been supplemented with 10% (w/w) of ginger and turmeric powders derived from commercial products (GC—commercial ginger and TC—commercial turmeric), freeze-dried rhizomes (freeze-dried ginger (GR) and freeze-dried turmeric rhizome—TR) and peels (freeze-dried ginger peel (GP) and freeze-dried turmeric peel—TP) for developing a functional seasoning with great lipid stability for human consumption. The exhausted ginger and turmeric powders were also recovered and recycled two times to promote a more sustainable process. The antioxidant activity and oxidative stability of oil samples were evaluated respectively by spectrophotometric and Rancimat methods. Folin–Ciocalteu assay and HPLC analysis were also performed to quantify total polyphenols, ginger-derived 6-gingerol and 6-shogaol, and turmeric-derived curcumin. Their antioxidant activity as well as oxidative stability, which non-linearly decreased over cycles because of a strongly reduced phenolic extractability, linearly increased with increasing phenolic yields. Hence, ginger and turmeric can be proposed as healthy spices containing bioactive compounds to control lipid oxidation and improve oil stability. Moreover, the valorization of peels as eco-friendly source of natural antioxidants is a valid strategy for providing added-value to these agro-food wastes.

Oxidative stability of direct-expanded chickpea-sorghum snacks

In contrast to other pulses, chickpea has a relatively high fat content (3%-10%). This study was designed to investigate direct-expanded chickpea-sorghum extruded snacks (50:50, 60:40, and 70:30 chickpea:sorghum, w/w) with respect to: their oxidative stability and sensory properties during accelerated (55°C) and room temperature (25°C) storage; correlations between chemical markers (peroxide value and p-anisidine value) and sensory data during accelerated storage; and the shelf-life of snacks extruded at the optimal expansion point as determined by a rotatable central composite design. Peroxide values and p-anisidine values were in the range of 0-2.5 mEq/Kg and 5-30, respectively, for both accelerated and room temperature storage, and increased during storage (p < .05). 70:30 and 60:40 (w/w) chickpea-sorghum snacks had higher peroxide and p-anisidine values compared to the 50:50 snack during storage at either temperature (p < .05). Rancid aroma and off-flavor of 60:40 and 70:30 chickpea-sorghum snacks (slightly intense = 6) also were higher than that of the 50:50 snack (moderately weak = 3) (p < .05). Significant correlations (p < .05) were found between chemical markers and sensory attributes (p < .05). The study illustrated that shelf-life decreased as the percentage of chickpea in the blend increased. Therefore, in terms of shelf-life, a 50:50 chickpea-sorghum blend is preferable.

A review of drying methods for improving the quality of dried herbs

A large number of herb-drying studies have been conducted in recent decades and several herb-drying techniques have been introduced. However, the quality of commercial dried herbs is still lower than that of fresh herbs. In this paper, studies regarding the effect of drying techniques and pre-drying treatments on the aroma and color of dried herbs are reviewed with the aim of providing an overview of different technological strategies developed for improving the quality of aromatic herbs for their industrial drying.

Examination of marine and vegetable oil oxidation data from a multi-year, third-party database

Fish oil (FO) products constitute good sources of omega-3 fats. Oxidation data from a large third-party database of 1900 + globally-sourced FO samples were assessed. In FO products, for peroxide value (PV), 13.9% exceeded 5 mEq O₂/kg (2.2% >10); for acid value (AcV) 2.1% exceeded 3 mg KOH/g, while for p-anisidine value (pAV) in unflavoured oils, 6.1% exceeded 20, (3.8% >30), and 8.8% exceeded TOTOX limits (26). Additionally, we compared FO with other dietary oils. The FO median PV was similar to those of algal and sunflower oils, 4.8-fold greater than krill oil, and 5.2-fold less than extra-virgin olive oil. The median pAV differed non-significantly among oils. The FO median AcV was similar to those of algal and extra-virgin olive oils, 3.4-fold greater than sunflower oil, and 11.9-fold less than krill oil. This study has provided new insight that retail FO products predominantly meet regulatory guidelines and are comparable in oxidative status to other dietary oils.

Lipid oxidation-related characteristics of gim bugak (Korean fried cuisine with Porphyra) affected by frying oil

The effect of frying oil on the lipid oxidation, antioxidants, and in vitro antioxidant activity of gim bugak was studied. Bugak was prepared by pan-frying at 180 °C in unroasted sesame, soybean, extra virgin olive, or palm oil. The degree of lipid oxidation based on conjugated dienoic acid and p-anisidine values was higher in the bugak fried in soybean or sesame oil with high contents of polyunsaturated fatty acids and tocopherols. However, the oil oxidation was lower in olive and palm oils, which showed higher degradation of tocopherols and polyphenols than in sesame or soybean oil during frying. Although the bugak fried in palm oil contained less antioxidants than that fried in soybean or sesame oil, the in vitro antioxidant activity was not different (p > 0.05). Results suggest that palm oil can replace unroasted sesame oil for the preparation of gim bugak with improved lipid oxidative stability and health functionality.

Effect of ascorbyl palmitate on oxidative stability of chemically interesterified cottonseed and olive oils

The effects of 400 ppm ascorbyl palmitate (AP) on fatty acids composition, tocopherol, peroxide value (PV) and malonaldehyde (MAD) contents of refined cottonseed oil (CO) and virgin olive oil (OO) during chemical interesterification (CI), and storage at 60 °C for 28 days were investigated. CI significantly decreased (p < 0.05) the tocopherol contents of CO and OO. PVs and MAD contents of oil samples considerably increased up to 20 min of CI, followed by a reduction at 30 min. The unsaturated fatty acids/saturated fatty acids (UFA/SFA) ratios of the samples showed slight but significant (p < 0.05) reduction during accelerated oxidation process. Oils with added 400 ppm AP had higher tocopherol, and lower PVs and MAD contents than their counterparts without AP during CI, and storage at 60 °C. AP increased the oxidative stability of interesterified and non-interesterified CO and OO.

Effects of solubility characteristics of sensitiser and pH on the photooxidation of oil in tuna oil-added acidic O/W emulsions

The effects of sensitisers and pH on the oil oxidation of acidic O/W emulsions were studied under light by measuring hydroperoxide content and headspace oxygen consumption in the emulsions. The emulsions consisted of canola and tuna oil (2:1w/w, 32%), diluted acetic acid (64%), egg yolk powder (4%), chlorophyll b or erythrosine (5μM), and/or diazabicyclooctane (DABCO) or sodium azide (0.5M). The emulsion pH values were 2.67, 3.68, and 6.27. Chlorophyll increased oil oxidation in the emulsion under light via singlet oxygen production while erythrosine did not. DABCO significantly decreased photooxidation of the oil containing chlorophyll, suggesting singlet oxygen involvement. However, sodium azide increased photooxidation of the oil containing chlorophyll possibly via azide radical production under acidic conditions. The oil photooxidation was higher in the emulsion containing chlorophyll at pH 6.27 than at pH 2.67 or 3.68, primarily by singlet oxygen and secondarily by free radicals produced from hydroperoxide decomposition.

Temperature dependence of autoxidation of perilla oil and tocopherol degradation

Temperature dependence of the autoxidation of perilla oil and tocopherol degradation was studied with corn oil as a reference. The oils were oxidized in the dark at 20, 40, 60, and 80 degrees C. Oil oxidation was determined by peroxide and conjugated dienoic acid values. Tocopherols in the oils were quantified by HPLC. The oxidation of both oils increased with oxidation time and temperature. Induction periods for oil autoxidation decreased with temperature, and were longer in corn oil than in perilla oil, indicating higher sensitivity of perilla oil to oxidation. However, time lag for tocopherol degradation was longer in perilla oil, indicating higher stability of tocopherols in perilla oil than in corn oil. Activation energies for oil autoxidation and tocopherol degradation were higher in perilla oil (23.9 to 24.2, 9.8 kcal/mol, respectively) than in corn oil (12.5 to 15.8, 8.8 kcal/mol, respectively) indicating higher temperature-dependence in perilla oil. Higher stability of tocopherols in perilla oil was highly related with polyphenols. The study suggests that more careful temperature control is required to decrease the autoxidation of perilla oil than that of corn oil, and polyphenols contributed to the oxidative stability of perilla oil by protecting tocopherols from degradation, especially at the early stage of oil autoxidation.