Antioxidant activity of ethanolic extract of Cortex fraxini and use in peanut oil

Cortex fraxini was extracted with 95% ethanol to obtain a crude antioxidant extract. The antioxidant activity was evaluated using the linoleic acid peroxidation method and the free radical scavenging assays, namely 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. Cortex fraxini extract (CFE) showed high inhibition of peroxidation of linoleic acid when compared with butylated hydroxytoluene (BHT). CFE also exhibited excellent scavenging activity on DPPH and hydroxyl radicals. Total antioxidant activity was measured by the reduction of Mo(VI) to Mo(V) by the extract, and subsequent formation of a green phosphate/Mo(V) complex at acid pH. CFE had significant total antioxidant activity and the effects were increased with increasing reaction time. The total phenolic content of the sample, analyzed by using Folin–Ciocalteu’s reagent, was 91.33 mg/g dry weight expressed as pyrocatechol equivalents. Then the suitability of CFE as an antioxidant was determined in peanut oil, and the decrease of lipid oxidation was monitored using thiobarbituric acid-reactive substances (TBARS) assay. CFE treatment significantly (P < 0.05) reduced lipid oxidation in peanut oil compared to the control. No significant differences (P = 0.05) in lipid oxidation were detected between CFE antioxidant and BHT antioxidant samples.     

Antioxidant potential of ethanolic extract of Polygonum cuspidatum and application in peanut oil

Polygonum cuspidatum was extracted with 95% ethanol to obtain a crude antioxidant extract. P. cuspidatum extract (PCE) had a very high content of total phenol, which was 104.83 ± 8.58 mg/g dry weight, expressed as pyrocatechol equivalent. PCE exhibited excellent antioxidant activity, as measured using α,α-diphenyl-β-picryhydrazyl (DPPH) and total antioxidant assays. It also showed a high lipid antioxidant activity and hydroxyl radicals scavenging activity. A positive correlation was found between the reducing power and the antioxidant activity of PCE, which was found to be comparable to resveratrol and butylated hydroxytoluene (BHT). Then the suitability of PCE as an antioxidant was determined in peanut oil, and the decrease of oxidation was monitored using thiobarbituric acid-reactive substances (TBARS) assay. PCE treatment significantly (P <  0.05) reduced lipid oxidation in peanut oil compared to resveratrol and BHT.     

Effect of fish (Catla catla) frying on the quality characteristics of sunflower oil

The quality of sunflower oil, as affected by fish (Catla catla) frying at 180 °C for 14 h was investigated. The purpose of the study was to find out the quality deterioration of sunflower oil with respect to time as affected by fish frying and to generate equations that can be used for predicting the quality parameters. The physico-chemical characteristics of sunflower oil were evaluated by drawing out the oil samples (75 ml) from the fryer at an interval of 2 h. The parameters evaluated were refractive index, colour, total polar material, free fatty acids, iodine value and peroxide value. There was a gradual increase in refractive index and colour with time of frying which was found to be significant (P < 0.05) in the latter. Iodine value decreased significantly (P < 0.05) with time of frying. Peroxide value first increased up to 12 h of frying and then decreased. After 10 h of frying, the total polar materials were 26.9%, indicating the need for replenishment or refinement of sunflower oil. Total polar material correlated well (r > 0.97) with colour, free fatty acids, peroxide value and time of frying. Free fatty acids correlated well (r > 0.96) with colour, total polar material and duration of frying. Fit of the equations was determined for total polar material and free fatty acids as a function of the respective correlated parameters.     

Use of natural antioxidants in refined palm olein during repeated deep-fat frying

An optimization study on the use of oleoresin rosemary extract, sage extract and citric acid added into refined, bleached and deodorized (RBD) palm olein before deep-fat frying of potato chips was performed using a constrained mixture design. Results revealed that the use of these natural antioxidants could improve the sensory acceptability of potato chips during a 5-day repeated deep-fat frying. All three antioxidants significantly (P<0.05) improved the sensory characteristics, including appearance, taste, crispiness, odor and overall acceptability. After day 5 of frying, the most acceptable fried potato chips were those fried in oil containing a combination of 0.059% oleoresin rosemary extract, 0.063% sage extract and 0.028% citric acid. The natural antioxidants significantly (P<0.05) lowered the rate of oxidation of oil during deep-fat frying and contributed to measured sensory acceptability of fried potato chips.     

Characterisation of phenolic compounds of Inca muña (Clinopodium bolivianum) leaves and the feasibility of their application to improve the oxidative stability of soybean oil during frying

Phenolic compounds from Inca muña leaves were, for the first time, qualitatively and quantitatively characterised. The main phenolic compounds encountered corresponded to flavanones, followed by flavones and hydroxycinnamic acid derivatives. Fractionation of Inca muña phenolic compounds revealed an ethyl acetate fraction (EaF) rich in phenolics and antioxidant activity. This EaF proved to be an efficient source of natural antioxidants for use against soybean oil oxidation during frying. Differential scanning calorimetry revealed higher induction periods for 600 ppm of EaF compared to 200 ppm of TBHQ and a negative control (no antioxidant added). During frying at ∼180 °C, 600 ppm of EaF showed the highest efficacy against oil oxidation in terms of p-anisidine values, conjugated dienes and trienes and polar compounds compared to 200 ppm of TBHQ and negative control. This study provides strong evidence for the antioxidant potential of Inca muña EaF phenolics against soybean oil oxidation. It suggests the possibility of incorporating these natural antioxidants from Inca muña leaves for use by the food industry.     

Supercritical carbon dioxide fluid extraction of Hibiscus cannabinus L. seed oil: A potential solvent-free and high antioxidative edible oil

The supercritical fluid extraction (SFE) trends and antioxidant activities of Hibiscus cannabinus seed oils were studied. SFE results indicate that extraction pressure is the major factor determining the oil yield. In comparison, classic Soxhlet extraction (SOX/L) yielded higher oil content than SFE (P < 0.05). However, no significant differences in oil content were observed in SFE at 600 bars/80 °C, rapid Soxhlet extraction (SOX/S) and conventional ultra-sonic assisted solvent extraction (SONIC) (P > 0.05). Antioxidant activities of H. cannabinus seed oils were compared with 7 types of commercial edible oils. DPPH scavenging activity test indicated that H. cannabinus seed oil extracted by SFE at 200 bars/80 °C possessed the highest antiradical activity whereas beta-carotene bleaching (BCB) assay revealed that all H. cannabinus seed oils (except for SFE at 400 bars/80 °C and 600 bars/80 °C) exhibited higher antioxidant activity than all commercial edible oils (P < 0.05). Thus, SFE – H. cannabinus seed oil may serve as an excellent source of solvent-free edible oil with high antioxidant properties.     

Phenolic content and antioxidant activity of cantaloupe (cucumis melo) methanolic extracts

The objectives of this study were to determine phenolic content and antioxidant activity of methanolic extracts from different parts of cantaloupe (leaf, stem, skin, seed and flesh). The flesh extract afforded the highest yield (89.6 ± 0.3%) whilst the lowest yield was obtained from the seed (13.7 ± 0.5%) (p < 0.05). The leaf extract showed the highest total phenolic content (26.4 ± 0.3 mg GAE/g extract) and total flavonoid content (69.7 ± 3.37 μg RE/g extract) accompanied with best antioxidant activity through all antioxidant assays (p < 0.05). In addition, the stem extract also exhibited good antioxidant activity. Thus, these results suggest that methanolic extracts of cantaloupe leaf and stem may serve as a potential source of natural antioxidant for food and nutraceutical application.     

Antioxidative effect of added dried Holy basil and its ethanolic extracts on susceptibility of cooked ground pork to lipid oxidation

Efficacy of varying concentrations of dried Holy basil powder and its ethanolic extracts in retarding oxidative rancidity was tested with cooked ground pork. The development of lipid oxidation products during 14 days refrigerated storage (5 °C) was evaluated by means of thiobarbituric acid-reactive substances (TBARS) value, peroxide value (POV), conjugated diene and hexanal content. In the amounts studied, dried Holy basil powder and its ethanolic extract significantly (P < 0.05) inhibited the formation of TBARS, peroxide, conjugated dienes and hexanal in a dose-dependent manner. The oxidation process was significantly (P < 0.05) influenced by the type of antioxidant and its concentration. Addition of dried Holy basil powder to cooked ground pork was more effective in inhibiting lipid oxidation than its ethanolic extracts. Additionally, TBARS values and hexanal contents in cooked ground pork were highly correlated (r² = 0.95; P < 0.05) with each other.     

The antioxidative properties of mustard leaf (Brassica juncea) kimchi extracts on refrigerated raw ground pork meat against lipid oxidation

The efficacy of varying concentration of mustard leaf kimchi ethanolic extracts (MK) in retarding oxidative rancidity was tested with raw ground pork. Freshly ground pork meat was assigned to one of the following five treatments: control (no antioxidants); AC-0.02 (0.02% ascorbic acid); MK-0.05, 0.1, and 0.2 (0.05%, 0.1% and 0.2% MK, respectively). The pH of the samples decreased and the TBARS values and free fatty acids (%) increased considerably (P < 0.05) during storage. The total bacterial count was lower in MK-0.1 and MK-0.2 than the control during storage. The internal L∗ value and a∗ value decreased (P < 0.05) with the addition of MK. The internal b∗ value of MK treatments were higher (P < 0.05) than that for the control and increased incrementally with MK concentration. The TBARS values and free fatty acids (%) of MK-0.02 was lowest among the treatments. The peroxide value of the control increased until 7 days and reached the maximum value at a certain storage time and decreased thereafter. In the other treatments it increased. All treatments had lower concentration of conjugated dienes (P < 0.05) compared to the control sample, after the first day. Mustard leaf kimchi ethanolic extracts exhibited a protective effect against lipid oxidation in raw ground pork.     

Antioxidant capacity and inhibitory effect of grape seed and rosemary extract in marinades on the formation of heterocyclic amines in fried beef patties

The effect of oil-based marinades containing grape seed extract (Vitis vinifera L.; 0.2, 0.4, 0.6 and 0.8 g/100 g) formulated in a water/oil emulsion or rosemary extract (Rosmarinus officinalis; 0.12, 0.2, 0.6, 1.0 and 1.5 g/100 g) in oil on the formation of heterocyclic amines (HAs) in fried beef patties was examined. After application of marinades and frying, four HAs MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline), PhIP (2-amino-1-methyl-6-phenylimidazo[4,5b]pyridine), Norharman, and Harman were found at low levels in all fried patties, MeIQx (0.3–1.0 ng/g), and PhIP (0.02–0.3 ng/g). The content of MeIQx and PhIP were significantly reduced by approx. 57% and 90% (p < 0.05), respectively, after use of marinades containing the highest extract concentration. The antioxidant capacity of grape seed was about two-times greater than that of rosemary extract. A correlation between inhibition of HAs and Trolox-equivalents (MeIQx, R² = 0.85, p < 0.001; PhIP, R² = 0.83, p < 0.001) was found. Sensory tests showed a high acceptance of flavour and colour for controls and samples.     

Evaluation of the effects of selected phytochemicals on quality indices and sensorial properties of raw and cooked pork stored in different packaging systems

The effects of lutein (100, 200 μg/g muscle), sesamol (250, 500 μg/g muscle), ellagic acid (300, 600 μg/g muscle) and olive leaf extract (100, 200 μg/g muscle) on lipid oxidation (thiobarbituric acid-reactive substances TBARs), colour (CIE L∗, a∗, b∗), pH, texture profile analysis (TPA), water holding capacity (WHC), cooking losses and sensorial properties of fresh and cooked pork patties were investigated. Raw and cooked minced pork (M. longissimus thoracis et lumborum) containing added lutein, sesamol, ellagic acid or olive leaf extract were stored aerobically or in modified atmosphere packs (MAP) for up to 8 and 12 days, respectively. Lutein, sesamol, ellagic acid and olive leaf extract had no significant effect on microbial status, cook loss, pH or WHC. Lipid oxidation was reduced (P < 0.001) in raw and cooked pork patties stored in aerobic packs and in MAP following addition of sesamol, ellagic acid and olive leaf extract. Antioxidant effectiveness in raw and cooked patties was in the order: sesamol = ellagic acid > olive leaf extract > lutein. Lutein increased (P < 0.001) b∗ yellowness values in raw pork patties. Addition of lutein, sesamol, ellagic acid and olive leaf extract to pork had no detrimental effects on the organoleptic properties of cooked patties but altered (P < 0.05) instrumental textural attributes. Results highlight the potential of using natural functional ingredients in the development of functional pork products with enhanced quality and shelf-life.     

Optimization of HS-SPME conditions for quantification of 2-acetyl-1-pyrroline and study of other volatiles in Pandanus amaryllifolius Roxb.

HS-SPME coupled with GC–FID was applied for the quantification of 2-acetyl-1-pyrroline (2AP) in Pandanus amaryllifolius, the best available natural source of (2AP). Conditions for qualitative and quantitative analysis of aroma volatiles with special reference to 2AP from P. amaryllifolius have been optimized using HS-SPME/GC–FID. About 10 mg powdered leaf material at 80 °C temperature for 35 min was found to be the most effective combination for maximum release of 2AP. Volatile analyses led to the identification of 31 compounds, of which 21 are reported for the first time in P. amaryllifolius. 2AP contents and other volatiles were found to vary in small and large growth forms.     

Antioxidant activity of microwave-assisted extract of longan (Dimocarpus Longan Lour.) peel

The longan (Dimocarpus Longan Lour.) peel was extracted with 95% ethanol employing microwave-assisted extraction and Soxhlet extraction method, the total phenolic content of microwave-assisted extract of Langan peel (MEL) and Soxhlet extract of Langan peel (SEL) reached 96.78 mg/g and 90.35 mg/g dry weight, respectively, expressed as pyrocatechol equivalents, which were quantified using Folin–Ciocalteu reagent. Subsequently, antioxidant properties of two extracts were investigated employing various established systems in vitro including 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, hydroxyl radical scavenging assay using a new resonance scattering (RS) method, reducing power and total antioxidant capacity. MEL and SEL showed excellent antioxidant in all test systems compared to synthetic antioxidant 2,6-di-ter-butyl-4-methylphenol (BHT) and the antioxidant activities of MEL were all superior to those of SEL. Furthermore, the suitability of MEL and SEL as substitute of BHT were determined in peanut oil, and the decrease of lipid oxidation were monitored using thiobarbituric acid-reactive substances (TBARS) assay. MEL and SEL treatment significantly (P < 0.05) reduced lipid oxidation in peanut oil compared to the control. No significant differences (P=0.05)$P=0.05)$ in lipid oxidation were detected between MEL, SEL and BHT samples of peanut oil.     

Effect of lutein,sesamol, ellagic acid and olive leaf extract on the quality and shelf-life stability of packaged raw minced beef patties

The effects of lutein (100 and 200 μg/g muscle), sesamol (250 and 500 μg/g muscle), ellagic acid (300 and 600 μg/g muscle) and olive leaf extract (100 and 200 μg/g muscle) on total viable counts (TVCs), lipid oxidation (thiobarbituric acid-reactive substances, TBARS), colour, oxymyoglobin oxidation, pH, water-holding capacity (WHC), sensorial properties of raw beef patties (M. longissimus thoracis et lumborum) stored in modified atmosphere packs (80% O₂:20% CO₂) (MAP) aerobically at 4 °C for up to 8 and 12 days, respectively, were examined. All the nutraceuticals reduced (P < 0.001) TVCs. The addition of sesamol, ellagic acid and olive leaf extract reduced (P < 0.001) TBARS in raw beef patties in both packaging systems. Sesamol addition to beef resulted in lower (P < 0.01) a* redness values and increased oxymyoglobin oxidation. Conversely, lutein and olive leaf extract reduced (P < 0.001) oxymyoglobin oxidation relative to the control. The graded addition of ellagic acid and olive leaf extract improved (P < 0.001) WHC.     

Oxidative and thermal stabilities of genetically modified high oleic sunflower oil

The oxidative and thermal stabilities of genetically modified high oleic sunflower oil (87% oleic acid) were compared with those of regular sunflower (17% oleic acid), soybean, corn, and peanut oils during storage at 55 °C and simulated deep fat frying at 185 °C. Oxidative stability was evaluated by measuring the oxygen content and volatile compounds in the sample bottle headspace and peroxide value. The coefficient variations (CVs) for volatile compound, headspace oxygen, and peroxide value analyses were 2.02%, 1.41%, and 3.18%, respectively. The oxidative stability of high oleic sunflower oil was greater than those of regular sunflower and soybean oil (P < 0.05) and as good as those of corn and peanut oils (P > 0.05). The thermal stabilities of oils during deep fat frying were evaluated by measuring the infrared absorption at 2.9 μm and conjugated diene content. The CV of conjugated diene content was 1.07%. Infrared and conjugated diene results showed that the high oleic sunflower oil had greater thermal stability than had regular sunflower, soybean, corn, and peanut oils (P < 0.05). The genetically modified high oleic sunflower oil, with 5.5% linoleic acid, had better oxidative and thermal stabilities than had the regular sunflower oil with 71.6% linoleic acid.     

Antioxidant versus anti-diabetic properties of leaves from Vernonia amygdalina Del. growing in Malaysia

The antioxidant and anti-diabetic properties of the sequential extracts of Vernonia amygdalina based on the chemical composition of the most effective anti-diabetic extract were studied. Using DPPH and ABTS radical scavenging as well as FRAP assays, the extracts showed a consistent dose-dependent trend of potent antioxidant activity in the following solvents: water extract > methanol extract > chloroform extract > and petroleum ether extracts. In the oral glucose tolerance test, the chloroform extract exerted the highest response (33.3%), similar to metformin (27.2%), after 2 h compared to the control (50.8%, P < 0.05). After a 14-day administration in diabetic rats, the chloroform extract recorded the highest blood (23.5%) and serum (21.4%) glucose-lowering effects (P < 0.05). GC–MS analysis of the chloroform extract revealed high levels of linoleic acid (4.72%), α-linolenic acid (10.8%) and phytols (12.0%), as well as other compounds.     

Chemical composition and antioxidant activity of the essential oil of Clinopodium vulgare L.

This study was designed to examine the chemical composition and in vitro antioxidant activity of the essential oil of Clinopodium vulgare. GC–MS analysis of the oil resulted in the identification of 40 compounds, representing 99.4% of the oil; thymol (38.9%), γ-terpinene (29.6%) and p-cymene (9.1%) were the main components. The samples were subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In the first case, IC₅₀ value of the C. vulgare essential oil was determined as 63.0 ± 2.71 μg/ml. IC₅₀ value of thymol and γ-terpinene, the major compounds of the oil, was determined as 161 ± 1.3 μg/ml and 122 ± 2.5 μg/ml, respectively, whereas p-cymene did not show antioxidant activity. In β-carotene-linoleic acid system, C. vulgare essential oil exhibited 52.3 ± 1.19% inhibition against linoleic acid oxidation. In both systems, antioxidant capacities of BHT, curcumine and ascorbic acid were also determined in parallel experiments.     

Evaluation of the effects of selected plant-derived nutraceuticals on the quality and shelf-life stability of raw and cooked pork sausages

The effect of lutein (200 μg/g meat), sesamol (250 μg/g meat), ellagic acid (300 μg/g meat) and olive leaf extract (200 μg/g meat) on total viable counts (TVC), pH, water holding capacity (WHC), cooking loss, lipid oxidation (thiobarbituric acid-reactive substances, TBARs), colour stability, texture and sensory evaluation of fresh and cooked pork sausages stored in aerobic or modified atmosphere packs (MAP) was investigated. Addition of sesamol, ellagic acid and olive leaf extract reduced (P < 0.001) lipid oxidation in all packaged raw and cooked pork sausages. Antioxidant potency followed the order: sesamol 250 > ellagic acid 300 > olive leaf extract 200 > lutein 200 for both raw and cooked pork sausages. Addition of sesamol increased (P < 0.001) WHC on days 2 and 12 of MAP storage. Meat addition of lutein, sesamol, ellagic acid and olive leaf extract had no detrimental effect on pH, cooking losses, TVCs, tenderness, juiciness, texture or product flavour. Lutein, sesamol, ellagic acid and olive leaf extract were effective as natural functional ingredients in suppressing lipid oxidation and have the potential to be incorporated into functional raw and cooked pork sausages.     

The hydroxycinnamic acid content of barley and brewers’ spent grain (BSG) and the potential to incorporate phenolic extracts of BSG as antioxidants into fruit beverages

The hydroxycinnamic acid (HA) content of starting barley for brewers’ spent grains (BSG), whole BSG and phenolic extracts from BSG was measured using high performance liquid chromatography (HPLC) and correlated with antioxidant potential. The effect of BSG phenolic extracts on antioxidant activity of fruit beverages was also assessed (using the total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays). The concentration of HA present in barley extract and BSG was in the order of ferulic acid (FA), p-coumaric acid (p-CA) derivatives, FA derivatives, p-CA, caffeic acid (CA) and CA derivatives. Results suggested that brewing and roasting decreased the HA content. Antioxidant activity was significantly (P < 0.05) correlated with caffeic acid (R² = 0.8309) and total HA (R² = 0.3942) concentrations. Addition of extracts to fruit beverages resulted in a significant (P < 0.05) increase in antioxidant activity of cranberry juice, measured by the FRAP assay. In vitro digestion significantly (P < 0.05) reduced TPC, DPPH and FRAP activity of the fruit beverages.     

Antioxidative characteristics of aqueous and ethanol extracts of glossy privet fruit

Non-enzymatic antioxidant activities of aqueous extract, 50% ethanol extract and 75% ethanol extract of glossy privet fruit were examined. Aqueous and ethanol extracts contained various concentrations of phenolic acids, flavonoids, oleanolic acid and ursolic acid. Each extract scavenged superoxide anion, hydroxyl radical and nitric oxide (P < 0.05) in a concentration-dependent manner and the effect of 75% ethanol extract was significantly greater than other extracts (P < 0.05). Each extract showed a concentration-dependent effect on chelating effect, xanthine oxidase inhibition activity and reducing power (P < 0.05). Compared with controls, each extract significantly decreased malondialdehyde formation in low density lipoprotein (LDL) and 8-epi-PGF_2α formation in plasma (P < 0.05). Aqueous extract exerted a greater effect than ethanol extract on increasing catalase and glutathione peroxidase activities in plasma (P < 0.05). These data suggest that using glossy privet fruit extracts may enhance lipid stability in food systems, and provide antioxidative protection for LDL and plasma.