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.     

Effect of natural antioxidants in controlling alkaline contaminant materials (ACM) in heated palm olein

A spectrophotometric-based method was developed to determine the changes in alkaline contaminant materials (ACM) of natural antioxidant-treated, refined, bleached and deodorized (RBD) palm olein during 5-day deep-fat frying of potato chips. Results showed that the ACM contents in RBD palm olein could be determined spectrophotometrically at 540 nm. Oleoresin rosemary extract, sage extract and citric acid significantly (P<.05) lowered the ACM content in oil during 5-day deep-fat frying of potato chips. A combination of 0.087% oleoresin rosemary extract, 0.072% sage extract and 0.025% citric acid was required to achieve the minimum level of ACM after 5-day frying.     

Effect of frying oil quality and TBHQ on the shelf-life of potato crisps

Three different systems were used for the evaluation of the effect of frying oil quality and tertiarybutyl hydroquinone (TBHQ) on the shelf-life of fried potato crisps. Batches of potato slices were fried for 4 min at 30 min intervals over a period of 5 h day^?1 for eight consecutive days in refined, bleached and deodorised palm olein (RBD olein) without antioxidant (system 1); RBD containing 200 μg g^?1 TBHQ at the start of the experiment (system 2) and RBD olein which had TBHQ topped up to a level of 200 μg g^?1 at the start of each frying day (system 3). Sensory evaluation of crisps showed that there is an initial rapid decrease in shelf-life with increase in fry number in all systems. There was only a comparatively smaller effect on shelf-life with increase in fry number in later fryings. When the shelf-life of crisps was related to the quality of oil in the frying medium, it was found that the shelf-life of the product is only slightly affected when the oil had deteriorated beyond the acceptable limit of quality of frying oil, where the acceptable limit was taken as 27-30% polar components and 1–2 mg potassium hydroxide g^?1 oil. TBHQ does have a protective carry-through effect. The protective effect is more pronounced when TBHQ is topped up to a level of 200 μg g^?1 at the beginning of each frying day.     

Effectiveness of antioxidants on the stability of banana chips

The effectiveness of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in improving the stability of banana chips stored at 65°C were compared. Criteria used in the assessment of the stability of the chips included the determinations of peroxide, p-anisidine, acid and iodine values, E_1cm ^1% at 232 amd 268 nm and the C18:2/C16:0 ratio of oil extracted from banana chips. It was found that chips fried in refined, bleached and deodorised (RBD) olein containing BHA or BHT were more stable than chips fried in RBD olein without antioxidants. BHT was more effective than BHA in prolonging the shelf-life of of banana chips. The same order of effectiveness of the antioxidants was observed at 65°C and at room temperature (25°C).     

Effects of variety and stage of fruit ripeness on the physicochemical and sensory characteristics of deep‐fat‐fried banana chips

The quality of banana chips prepared from two different varieties of banana, Pisang Abu and Pisang Nangka, at the ‘green’ and ‘trace of yellow’ stages of ripeness was studied. The fruits were peeled, sliced to a thickness of 2 mm and deep‐fat fried in refined, bleached and deodorised (RBD) palm olein at 180 ± 5 °C for 3 min. The quality parameters determined for fresh bananas were total soluble solids, pH, acidity, carbohydrate, sugar content, fat, protein, moisture content, ash, fibre, colour and fruit firmness. The results showed that Abu had a higher carbohydrate content than Nangka at both stages of ripeness before frying. No sucrose was detected in Nangka. The quality parameters determined after deep‐fat frying were moisture content, water activity, oil absorption, crispness and sensory evaluation. The moisture content and water activity of Abu chips were lower than those of Nangka chips. The texture of chips prepared from Abu at stage ‘green’ showed more crispness than the other three samples. Sensory evaluation showed that chips prepared from Abu at both stages of ripeness presented better colour, flavour, odour, texture and overall acceptability than those prepared from Nangka. Based on the matrix of correlation coefficients, fresh bananas with higher fruit firmness and carbohydrate content gave banana chips with higher crispness and oil absorption. © 2001 Society of Chemical Industry     

Effects of silicone and ascorbyl palmitate on the quality of palm olein used for frying of prawn crackers

The effects of ascorbyl palmitate (AP) and silicone on the quality changes of refined, bleached and deodorised palm olein (RBD olein) during intermittent frying of prawn crackers for 4.5 h per day were evaluated. The percentage polar components, the C18:2/C16:0 fatty acid ratio, and the acid value of used frying oil without additives were comparable to those for oil containing 200 mg kg^?1 AP. Oil with 2 mg kg^?1 silicone as well as oil containing 200 mg kg^?1 AP plus 2 mg kg^?1 silicone that had been used for frying had lower percentage polar components, higher C18:2/C16:0 ratios and lower acid values than RBD olein without additive. The results showed that silicone had a protective effect on the oil but that the rate of deterioration of the oil in the presence of AP was comparable to that of oil without additive during frying of prawn crackers. The results also showed that the extent of oil oxidation in RBD olein subject to static heating at 180°C for 4.5 h per day for four consecutive days was comparable to that of RBD olein without additive that had been used for frying of prawn crackers.     

Performance of a lipase-catalyzed transesterified palm kernel olein and palm stearin blend in frying banana chips

The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1:1 by weight) blend was compared with its control (physical mixture or no enzyme added) and a commercial plastic frying shortening (CS). The samples were used as deep-fat frying media at 180°C for banana chips for seven consecutive days. The samples were then analysed for iodine value (IV), free fatty acid (FFA) content, peroxide value (PV), thiobarbituric acid (TBA) value, p-anisidine value (AV), total polar compounds (TPC), fatty acid composition, specific extinction, E^1%_1cm at 233 and 269 nm, polymer contents, viscosity and colour indices. The fried banana chips were analysed for acceptability by sensory evaluations. Storage properties of the banana chips were also evaluated by trained sensory panellists and a modified TBA test. The transesterified blend was found to have significantly (P<0.05) higher IV, FFA, PV, TBA value, AV, TPC, E^1%_1cm at 233 and 269 nm values, polymer content, viscosity and colour indices compared to the control, indicating that the transesterified blend was more susceptible to oxidative deterioration during deep-fat frying. CS generally showed the largest changes in most of the parameters, basically due to its high polyunsaturated fatty acid levels. There was no significant difference (P>0.05; for all the attributes tested) between the acceptability of the banana chips fried by the transesterified and control blends. However, the banana chips fried in CS had significantly (P<0.05) lower scores in terms of flavour, aftertaste and overall acceptability. This might be due to the typical hydrogenation flavour of CS. In the storage stability study of the banana chips, it was found that the banana chips fried in the transesterified blend were significantly (P<0.05) more rancid (lower score in sensory evaluations) and had a higher TBA value at the end of the storage time than the control.     

Deep Frying Performance of Enzymatically Synthesized Palm-Based Medium- and Long-Chain Triacylglycerols (MLCT) Oil Blends

The main aim of this work was to assess the frying strength of the enzymatically synthesized palm-based medium- and long-chain triacylglycerols (MLCT) oil with the aid of different antioxidants under deep-frying conditions. Palm-based MLCT oil in the presence of synthetic or natural antioxidants showed significantly better (P < 0.05) thermal resistance and oxidative strength than refined, bleached, and deodorized (RBD) palm olein throughout the five consecutive days of frying. Rancimat induction period, free fatty acid content, anisidine value, E^\text1% _1\textcm E^{{\text{1\% }}} _{1{\text{cm}}} at 232 and 268 nm, color, percentage of oil uptake, and viscosity measurement can be used as oil quality parameters to indicate the degree of oil deterioration under continuous stressed frying conditions. No significant changes (P > 0.05) in the saturated/unsaturated fatty acids ratio across frying periods indicated good oxidative stability of the palm-based MLCT oil. Due to the polarity of medium- and long-chain triacylglycerols in palm-based MLCT oil, total polar compounds determination may not be a suitable oil quality measures. Sensory evaluation of fried chips showed no significant differences (P > 0.05) between chips fried in RBD palm olein and palm-based MLCT oil over the 3-month storage period.     

Loss of tocopherols and formation of degradation compounds at frying temperatures in oils differing in degree of unsaturation and natural antioxidant content

Samples of oils of different degrees of unsaturation, namely palm olein, olive oil, high‐linoleic sunflower oil, high‐oleic sunflower oil, rapeseed oil and soybean oil, were heated at 180 °C for 2, 4, 6, 8 and 10 h in the presence or absence of their natural antioxidants. Also, tocopherol‐stripped oils were supplemented with α‐tocopherol (500 mg kg^?1), δ‐tocopherol (500 mg kg^?1) or a mixture of α‐, β‐, γ‐ and δ‐tocopherols (250 mg kg^?1 each) and heated under the same conditions. Losses of tocopherols and formation of polymeric triacylglycerols were followed. Total polar compounds were also evaluated after 10 h of heating. Results demonstrated that tocopherols were lost very rapidly, in the expected order, with α‐tocopherol being the least stable. Polymeric and polar compound formation during heating was inhibited to a variable extent, being more dependent on the natural content and type of tocopherols than on the degree of unsaturation of the oil. For example, polymeric and polar compound contents in soybean oil were significantly lower than those found in high‐linoleic sunflower oil. However, the expected influence of the degree of unsaturation was evident when oils were unprotected or possessed identical initial antioxidant contents. Finally, levels of degradation compounds after 10 h of heating were not dependent on the remaining content of antioxidants. © 2002 Society of Chemical Industry     

Effect of α‐tocopherol and α‐tocotrienol on the performance of Chilean hazelnut oil (Gevuina avellana Mol) at high temperature

The high temperature antioxidant efficiency of α‐tocopherol, α‐tocotrienol and a mixture of both on hazelnut oil were evaluated. Crude hazelnut oil (HZO), crude hazelnut oil treated with alumina (THZO), as well as three samples of THZO to which 150 mg kg^?1 of α‐tocopherol, 140 mg kg^?1 of α‐tocotrienol or a mixture containing 70 mg kg^?1 of α‐tocopherol and 70 mg kg^?1 of α‐tocotrienol, were added and submitted to thermal treatment at 180°C for 18 h. The addition of tocols to THZO decreased the formation of polar compounds and increased its oxidative stability in all the systems studied. However, α‐tocopherol showed a higher antioxidant capacity than α‐tocotrienol at high temperature. In addition, α‐tocotrienol showed a more rapid degradation rate than α‐tocopherol under the conditions studied. Copyright © 2004 Society of Chemical Industry     

Effect of tertiarybutylhydroquinone on lipid oxidation in fish crackers

The effect of tertiarybutylhydroquinone (TBHQ) in retarding lipid oxidation in fish crackers fried in refined, bleached and deodorised palm olein (RBD olein) during storage was evaluated. The indices of lipid oxidation used were the peroxide and p-anisidine values and u.v. absorbances at 232 and 268 nm of oil extracted from fish crackers stored at 60°C. Two methods for TBHQ incorporation into the fish crackers were used. Fish crackers that were prepared by frying of fish chips in RBD olein containing TBHQ were more stable towards oxidative rancidity than control fish crackers prepared with RBD olein without TBHQ. The rate of lipid oxidation in fish crackers prepared from fish chips that were made with TBHQ in the dough formulation and fried in RBD olein without TBHQ was slightly higher than in control fish crackers. A storage study carried out at room temperature (30°C) showed the same trend in relative rates of lipid oxidation. The study showed that the incorporation of TBHQ into the frying medium was an effective means of retarding the onset of rancidity in fried fish crackers while the incorporation of TBHQ into the dough mixture made the fish cracker slightly more susceptible towards lipid oxidative reactions.     

Oxidative stability of palm‐ and soybean‐based medium‐ and long‐chain triacylglycerol (MLCT) oil blends

BACKGROUND: Medium‐ and long‐chain triacylglyerols (MLCT) enzymatically esterified using Lipozyme RM IM lipase has very low oxidative stability as it does not contain any antioxidants. The aim of this work was to study the ability of various antioxidants to increase the oxidative stability of palm‐ and soybean‐based MLCT blends which assist to bring up the oxidative stability of both MLCT blends. In this study, the effectiveness of rosemary extracts, sage extracts, tert‐butylhydroquinone (TBHQ) and mixtures of tert‐butyl‐4‐hydroxyanisole (BHA) and tert‐butyl‐p‐hydroxytoluene (BHT) in protecting against oxidation of various MLCT blends was investigated. RESULTS: Blending of MLCT oil with either palm olein or soybean oil improved its smoke point values and oxidative stability. TBHQ addition to both palm‐ and soybean‐based MLCT blends increased oxidative stability. Combination of BHA and BHT showed no significant improvement (P > 0.05) in ability to protect blends from oxidation compared to natural antioxidants such as sage or rosemary extracts. CONCLUSION: Blended oils with 500 g kg^?1 MLCT and 500 g kg^?1 palm olein (MP5) were the most suitable for use at high temperature based on the fatty acid composition of the MLCT blends, which subsequently had an effect on thermal oxidative stability. In general, addition of either natural or synthetic antioxidant assisted in improving the antioxidative strength of both MLCT blends. MLCT blends with added TBHQ showed the highest thermal oxidative stability among the antioxidants used. Copyright © 2008 Society of Chemical Industry     

稻米油调和油煎炸应用研究

通过与棕榈油对比180℃下炸制薯片以及评估薯片感官喜好度、质构、口感及粘牙性等差异来评价稻米油调和油的煎炸应用性能。结果表明:采用稻米油调和油煎炸的薯片中多不饱和脂肪酸含量显著高于棕榈油(P<0.05),且其薯片的整体感官喜好度、质构口感、酥脆度、粘牙喜好度,均显著优于棕榈油薯片(P<0.05)。在加速氧化条件下,采用稻米油调和油炸制的薯片的酸价、过氧化值均与棕榈油炸制的薯片无显著性差异(P>0.05),且远低于GB 16565-2003的规定。在加速存储过程中,谷维素却得到了很好的保留。总之,稻米油调和油具有良好的煎炸性能。     

Change in α‐tocopherol contents,lipid oxidation and fatty acid profile in eggs enriched with linolenic acid or very long‐chain ω3 polyunsaturated fatty acids after different processing methods

The influences of dietary supplementation with α‐tocopheryl acetate (α‐TA) and of processing (by hard‐boiling and scrambling) of eggs enriched with ω3 fatty acids, either very long‐chain ω3 polyunsaturated fatty acids (VLC ω3 PUFAs) or linolenic acid (LNA), on fatty acid composition, α‐tocopherol content and lipid oxidation (thiobarbituric acid (TBA) values) were studied. Four dietary treatments were formulated from a basal diet containing 40 g kg^?1 linseed oil (LO) or fish oil (FO) combined with either 0 or 100 mg α‐TA kg^?1 of feed. Eggs from LO treatments were enriched with LNA and those from FO treatments were rich in VLC ω3 PUFAs. Neither processing nor dietary supplementation with α‐TA modified greatly the fatty acid profile of eggs. Dietary supplementation with α‐TA increased the α‐tocopherol content of eggs (187.2 versus 407.9 µg g^?1 dry matter). Eggs from FO treatments showed lower α‐tocopherol content than those from LO treatments (273.5 versus 321.6 µg g^?1 dry matter), and processing of eggs enriched with VLC ω3 PUFA reduced the α‐tocopherol content by a significant 16%. Moreover, processing of eggs increased lipid oxidation two‐ to nine‐fold. Oxidation levels of hard‐boiled eggs were 30.4% higher than those of scrambled eggs. TBA values in hard‐boiled and scrambled eggs were significantly reduced when 100 mg α‐TA kg^?1 of feed supplemented the diet only in those eggs enriched with VLC ω3 PUFA (from FO treatments). Copyright © 2003 Society of Chemical Industry     

QUALITY CHANGES OF REFINED-BLEACHED-DEODORIZED (RBD) PALM OLEIN, SOYBEAN OIL AND THEIR BLENDS DURING DEEP-FAT FRYING

The quality changes of refined, bleached and deodorized palm olein (RBDPO) and soybean oil (SBO) and their blends were investigated in this study. The oils were studied during intermittent frying of potato chips at 180PT5C for 5 h per day for 5 consecutive days. The indices used for assessment of changes in quality of the oils were fatty acid composition (FAC), peroxide value (PV), anisidine value (AnV), % free fatty acid (FFA), iodine value (IV), % polar component, polymer content, color, viscosity, smoke point and foaming tendency. The results showed that RBDPO was superior to SBO in frying performance in terms of resistance to oxidation, changes in IV, AnV, foaming tendency, % polar component and polymer content. However, SBO performed better than RBDPO with respect to color, viscosity, FAA content and smoke point. Sensory evaluation showed that potato chips fried in both RBDPO and SBO were equally acceptable by the panelists.     

Effect of superheated steam prefrying treatment on the quality of potato chips

Superheated steam drying (SSD) was used as a prefrying treatment prior to deep‐fat frying for potato slices. The effect of SSD at 130, 150 or 180 °C and steam velocity of 2.0 m s^?1 on the fat uptake, colour and texture of fried potato chips was evaluated; microstructure and degree of starch gelatinization were also evaluated to help explain the fat uptake results. SSD and frying yielded potato chips with the fat content from 0.263 ± 0.002 to 0.304 ± 0.002 kg kg^?1 (d.b.), while frying without SSD led to chips with the fat content as high as 0.359 ± 0.003 kg kg^?1 (d.b.). SSD did not promote starch gelatinization. Lower fat uptake was correlated to modified surface structure and lower moisture content of potato slices prior to frying. Frying with/without SSD pretreatment yielded potato chips of similar hardness, crispness and lightness. On the other hand, SSD significantly increased redness and yellowness of the fried chips.     

Supercritical CO2 extraction of Chilean hop (Humulus lupulus) ecotypes

Hops (Humulus lupulus L) have very stringent requirements of diurnal light hours during flowering. Thus, the beer industry is permanently assessing new agricultural land to grow hops, southern Chile being an excellent candidate for their introduction. Supercritical carbon dioxide extraction procedures were implemented to assess Chilean hop ecotypes. Based on results of a preliminary study with commercial samples (cv Nugget), 200 bar and 40 °C were selected as extraction conditions. Very limited increases in extraction rate were observed when applying pressures >200 bar; such pressures did not speed up the extraction of α‐acids (bitter flavor principles), but rather increased the co‐extraction of undesirable compounds (hard resins and chlorophyll pigments). On the other hand, the effects of retrograde condensation phenomena were just starting to subside at 200 bar, and thermal damage of samples could increase at >40 °C. Ground cone samples of five local hop ecotypes, originating from Osorno, La Junta, Coyhaique and Elizalde Lake, were subsequently tested. Osorno exhibited a higher yield (65 g kg^?1 oleoresin/substrate) than other Chilean ecotypes. Moreover, Osorno extract had a light yellowish color, as well as a higher content of bitter flavors (157 g kg^?1 α‐acid/extract) and 1.5–7.1 times more representative aroma compounds than extracts of the other ecotypes. However, all these indicators were very low compared with the commercial Nugget sample (134 g kg^?1 oleoresin/substrate, 383 g kg^?1 α‐acid/extract, 14 times more aroma compounds than Osorno ecotype). Copyright © 2003 Society of Chemical Industry     

Determination of acrylamide in Thai-conventional snacks from Nong Mon market,Chonburi using GC-MS technique

Acrylamide in Thai-conventional snacks was analysed by GC/MS with a linear response ranged of 5–50?µg and r ^2?>?0.99. The limit of detection (s/n?=?(3) and limit of quantification (s/n?=?10) were 4 and 15?µg?kg^?1, respectively, and RSD?<?2%. Acrylamide in 19 food samples ranged from <15?µg?kg^?1 to 1.26?mg?kg^?1 with highest concentrations in Kanom Jak. Moderate levels (150–500?µg?kg^?1) were detected mostly in deep-fried products, especially sweet potato and taro crisps, Kanom Kai Hong, banana fritters, durian chips and spring rolls. Thai-conventional snacks possessed low concentrations (<150?µg?kg^?1) including Khao Larm, Pa Tong Koo, sweet banana crisps and deep-fried Chinese wonton. Acrylamide was lowest (<15?µg?kg^?1) in fish strips, rice crackers, Hoi Jor and fried fish balls. Dietary habits by 400 tourists indicate a daily intake of acrylamide <150?ng, well below a toxic dose.     

Supercritical CO₂extraction of oleoresin from marigold (Tagetes erecta L.) flowers and determination of its antioxidant components with online HPLC-ABTS(·+) assay

BACKGROUND: Marigold is a traditional medicine herb which shows good pharmacological activity in many aspects. It is very important to obtain and investigate the specific bioactive compounds from marigold. The objective of the study was to extract the oleoresin from marigold with supercritical CO₂ (SC‐CO₂) at different pressures and temperatures, detect the fatty acid composition by gas chromatography–mass spectrometry and investigate the antioxidative components in the extracts by combined online high‐performance liquid chromatography‐2,2‐azinobis‐(3‐ethylbenzothiazolin‐6‐sulfonic acid (HPLC‐ABTS^?+) post‐column assay and HPLC‐tandem mass spectrometry. RESULTS: For the pressure range (20–40 MPa) and temperature range (30–70 °C), 30 MPa/70 °C gave the highest yield of oleoresin (58.9 g kg^?1). The dominant fatty acids of marigold flower oleoresin were linoleic acid (>26.41%), palmitic acid (>24.22%) and oleinic acid (>20.12%). Significant effects of the extraction pressure and temperature on the antioxidant activity were observed (P < 0.05). Lutein esters, α‐tocopherol, β‐tocopherol, γ‐tocopherol and δ‐tocopherol were the dominant antioxidant compounds in the extracts. CONCLUSION: The study has shown that the yield and total antioxidant activity of the marigold extracts were affected by the pressure and temperature of SC‐CO₂, and that online HPLC technique could be used as an efficient and rapid method for separation and identification of bioactive compounds from a complex mixture. Copyright © 2011 Society of Chemical Industry     

COMPARISON OF THE FRYING PERFORMANCE OF REFINED, BLEACHED AND DEODORIZED PALM OLEIN AND COCONUT OIL

The frying performance of refined, bleached and deodorized palm olein (RBDPO) and refined, bleached and deodorized coconut oil (RBDCO) was compared in this study. The oils were studied during intermittent frying of potato chips at 180C for 5 h/day for 5 consecutive days. The indices used for assessment of frying performance of the oils were fatty acid composition (FAC), peroxide value (PV), anisidine value (AnV), % free fatty acid (FFA), iodine value (IV), % polar component, polymer content, color, viscosity, smoke point and foaming tendency. The results showed that RBDPO was superior to RBDCO in frying performance in terms of % FFA, iodine value, foaming tendency and smoke point. However, RBDCO performed better than RBDPO with respect to % polar component, polymer content, resistance to oxidation, color and viscosity. Flavor evaluation showed that potato chips fried in RBDPO were preferred by the panelists.