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The relationship between the structure and the antioxidant activity of 21 hindered phenolic compounds was investigated by Rancimat and DPPH· tests. 3-Tert-butyl-5-methylbenzene-1,2-diol is the strongest antioxidant in the Rancimat test but not in the DPPH· test because its two hydroxyl groups have very strong steric synergy. 2,6-Ditert-butyl-4-hydroxy-methylphenol exhibits a strong antioxidant activity as 2,6-ditertbutyl- 4-methoxyphenol does in lard. 2,6-Ditert-butyl-4- hydroxy-methylphenol also exhibits stronger activity than 2-tert-butyl-4- methoxyphenol. The methylene of 2,6-ditert-butyl-4-hydroxy-methylphenol can provide a hydrogen atom to active free radicals like a phenolic hydroxyl group does because it is greatly activated by both the aromatic ring and hydroxyl group. Five factors affect the antioxidant activities of the phenolic compounds: how stable the phenolic compound free radicals are after providing hydrogen atoms; how many hydrogen atoms each of the phenolic compounds can provide; how fast the phenolic compounds provide hydrogen atoms; how easily the phenolic compound free radicals can combine with more active free radicals, and whether or not a new antioxidant can form after the phenolic compound provides hydrogen atoms. [ABSTRACT FROM AUTHOR]

The effectiveness of two lipophilic derivatives of the natural phenol, gallic acid (GA), synthesized using methyl gallate as starting material was investigated. The antioxidant activities of these novel phenolics compared to GA, tert-butylhydroquinone (TBHQ) and butylated hydroxytoluene (BHT) were evaluated in bulk oil, emulsion and the DPPH systems. The results showed that the new compounds effectively delayed lipid oxidation much better than GA and other antioxidants under Rancimat (100-140 °C) and emulsion tests. In the bulk oil system at 65 °C, they still behaved better than GA, but TBHQ had the highest activity. Thus, replacing the electron-withdrawing carboxylic group on GA by covalently linking sterically hindered phenols to its phenyl ring increased its lipophilicity and also resulted in synergistic effects which improved overall antioxidant activity through stabilization of the phenoxy radical. These new antioxidant variants satisfy industrial demands for bioactive ingredients with strong antioxidant potentials under different food processing conditions. [ABSTRACT FROM AUTHOR]

A novel caffeic acid derivative, butylated methyl caffeate (BMC), was synthesized via esterification between butylated caffeic acid (BCA) and methanol. Its antioxidant activity was investigated and compared to TBHQ, caffeic acid (CA), methyl caffeate (MC) and BCA through deep-frying, an oven test in oil-in-water emulsions and DPPH radical scavenging. BMC showed the strongest antioxidant activity among the five antioxidants in emulsions and its antioxidant activity was almost as strong as BCA in frying. Its soybean oil-water partition coefficient was 9.18 due to its ester and tert-butyl groups, far greater than those of MC (4.82), BCA (2.41), CA (0.84) and TBHQ (3.22). This meant that it was much more soluble in the lipid phase than the other four antioxidants in emulsions. The DPPH radical scavenging activity of BMC was near TBHQ, lower than the other three because of its steric hindrance and less functional phenolic hydroxyl groups compared to others when their masses were the same. [ABSTRACT FROM AUTHOR]

A novel compound, 6,6'-(butane-1,1-diyl)bis(4-methylbenzene-1,2-diol) (BMB), was synthesized through an acid-catalyzed condensation reaction between 4-methylcatechol (HPC) and butyraldehyde. When evaluated by the Rancimat and deep frying methods, BMB exhibited a stronger antioxidant activity than TBHQ. Its DPPH radical scavenging activity was also fairly higher than TBHQ, but lower compared to its mother phenol, HPC, due to its relative ease of binding DPPH•. BMB had the strongest scavenging ability of the 4-methylcatechol analogues reported to date. It could be used effectively to retard lipid peroxidation in both moderate and high temperature food preparations. [ABSTRACT FROM AUTHOR]

1,3-Dioleoyl-2-palmitoylglycerol (OPO) was synthesized by enzymatic interesterification using palm stearin rich in tripalmitin (PPP) and ethyl oleate. Enzymatic interesterification parameters such as temperature, water content, enzyme load, and substrate molar ratio were optimized. High contents of C52 (primarily OPO and its isomeric compounds) production (46.7%) and sn-2 palmitic acid (PA) content of 75.3% were detected. In addition, OPO-human milk fat substitute (HMFS) was blended with coconut, soybean, algal and microbial oils at a weight ratio of 0.70:0.18:0.11:0.004:0.007 to simulate fatty acids in human milk fat (HMF) according to the mathematical model. The main and important fatty acids in the Final-HMFS were within the ranges of those present in HMF. The Final-HMFS could promote the absorption of fats and minerals and the development of retina tissues in infants. The mixture of L-ascorbyl palmitate (L-AP) and vitamin E (VE) resulted in a synergistic antioxidant effect both in OPO-HMFS and OPO-HMFS emulsions. This finding has great significance in improving the quality and extending shelf-life of HMFS. [ABSTRACT FROM AUTHOR]

Potato cookies were formulated by replacing red palm stearin (RPS) by red palm olein (RPOL) at 0, 17 and 35%, and then baked at 160, 180 and 200 °C for 10, 12 and 15 min. The sensory analysis, using an orthogonal test, showed that a RPS-RPOL ratio of 65:35, baking temperature of 160 °C, and baking time 12 min were the optimal conditions. Cookies made from 65% RPS + 35% RPOL composition exhibited 0.6 times less squalene, but 1.5 times more β-carotene, tocopherols and tocotrienols than the mixture of RPS and RPOL at 100:0. In addition, cookies with superior oxidative stability were obtained at a lower temperature (160 °C) and short baking time (10 min). This study demonstrates that the application of RPOL and RPS blending can positively enhance the nutritional properties and oxidative stability of baked food, and that using potato in the baking processing may be beneficial. [ABSTRACT FROM AUTHOR]

The nuclear magnetic resonance (NMR) technique was applied to monitor the quality of tea oil herein. The adulteration of virgin tea oil was monitored by 19F NMR and ¹H NMR. The 19F NMR technique was used as a new method to detect the changes in quality and hydroperoxide value of tea oil. The research demonstrates that 19F NMR and 1H NMR can quickly detect adulteration in tea oil. High temperature caused a decrease in the ratio D and increase in the total diglyceride content. Some new peaks belonging to the derivatives of hydroperoxides appeared at δ-108.21 and δ-109.05 ppm on the 19F NMR spectrum when the oil was autoxidized and became larger when the hydroperoxide value increased. These results have great significance in monitoring the moisture content, freshness and oxidation status of oils and in detecting adulteration in high priced edible oils by mixing with cheap oils. [ABSTRACT FROM AUTHOR]

The baking conditions of walnut kernels were optimized based on different cultivars and baking methods. The influence of the different baking techniques on the chemical properties of walnut oils was determined. The results showed that acid value, peroxide value and induction period (IP) all significantly increased in the baked samples compared to the unbaked ones. The highest increase in IP was from 6 to 17 h indicating that baking can improve the oxidative stability of walnut oils and prolong their shelf-life. Several aroma components increased after baking. However, among the different baking conditions, the strongest aroma in walnut oil was observed after baking was done for 20 min with sucrose (107%) at 153 ?. Nevertheless, baking had little effect on the fatty acid composition of walnuts. [ABSTRACT FROM AUTHOR]

Extruded potato (P) and sweet potato (SP) products with red palm oil (RPO) were prepared under different conditions. Superior product characteristics such as sensory score, expansion ratio, and water solubility index, among others, were obtained at high extrusion temperature (150-155 °C) and low water feed rate to the extruder (50.4-50.8 mL/min). The optimal products, P1 and SP1, had high micronutrients as their total contents of ß-carotene, squalene, tocopherols, and tocotrienols were 883.2, 304.4, 262.4, and 397.0 mg/kg of oil, respectively. The average peroxide value was 4.3 meq O2/kg oil, p-anisidine value 3.3, and induction period (100 °C) 11.4 h. Moreover, RPO extruded with P showed a better extrusion behavior but lower micronutrient retention and oxidative stability than that extruded with SP. Thus, the finding herein is important for investigating extrusion conditions, increasing variety, improving nutritional quality, assessing applicability and predicting the shelf-life of RPO-P/SP-extruded food. [ABSTRACT FROM AUTHOR]

This paper reports the comparison of determination methods for extra virgin olive oil (EVOO) adulteration with two kinds of oils, refined olive oil (ROO) and soybean oil by 19FNMR, 1H NMR and chemical titration. The determination of adulteration of EVOO with ROO by 19F NMR was comparable to the conventional method. The contents of oleic, linoleic and linolenic acids of different oil samples can be determined by both 1H NMR and GC-MS. The results obtained from the two methods showed little differences. The adulteration of EVOO with soybean oil is detected by 1H NMR, although the limit of detection of the adulteration level is not less than 4.5%. The research demonstrates that 19F NMR can be a fast and convenient method to detect EVOO if it is adulterated with ROO and 1H NMR can be a fast and convenient method to detect EVOO if it is adulterated with seed oils. [ABSTRACT FROM AUTHOR]