Detection of lard adulteration in RBD palm olein using an electronic nose

The use of surface acoustic wave (SAW) sensing electronic nose (zNose™) for detection of lard as an adulterant in refined, bleached, deodorized (RBD) palm olein was investigated. Mixing of animal fats, especially lard in any form in food products, is a cause of concern for certain religions. RBD palm olein spiked with lard at levels ranging from 1% to 20% (w/w) was analyzed. The zNose™ produced a two-dimensional olfactory image called VaporPrint™, which could be used for immediate detection (qualitatively) of lard substances in sample admixtures. Lard adulteration could be determined by a few distinct peaks in the zNose™ chromatogram. The best relationship between percentage of lard in adulterated RBD palm olein and SAW detector response was observed in adulterant peak E (R² = 0.906). Pearson’s correlation coefficient (r) was calculated using this parameter. An ideal correlation was observed between the zNose™ data and other chemical tests (r > 0.90).     

Crystallisation kinetics of palm stearin,palm kernel olein and their blends

The kinetics of isothermal crystallisation of palm stearin, palm kernel olein and their blends (20–80 g/100 g palm stearin with 20 g/100 g increment) were determined using differential scanning calorimetry (DSC). The mechanism of crystallisation (n) was calculated by applying the Avrami equation using the crystallisation curves obtained at 10, 15 and 20 °C. The DSC isothermal crystallisation data at 10, 15 and 20 °C fitted well into the Avrami equation over the entire fractional crystallisation with correlation coefficient always greater than 0.98. Based on the Avrami exponent obtained, the palm stearin and palm kernel olein have different nucleation and growth mechanisms. The suggested mechanism for palm kernel olein was high nucleation rate at the beginning of crystallisation, which decreased with time, and plate-like growth (n = 2). On the other hand, the mechanism for palm stearin was instantaneous heterogeneous nucleation followed by spherulitic growth (n = 3). For blends of palm stearin and palm kernel olein, the mechanisms of crystallisation were 2 and 3 depending on the composition of the blends and crystallisation temperatures.     

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.     

Effects of chemical interesterification on physicochemical properties of blends of palm stearin and palm olein

Chemical interesterification is an important technological option for the production of fats targeting commercial applications. Fat blends, formulated by binary blends of palm stearin and palm olein in different ratios, were subjected to chemical interesterification. The following determinations, before and after the interesterification reactions, were done: fatty acid composition, softening point, melting point, solid fat content and consistency. For the analytical responses a multiple regression statistical model was applied. This study has shown that blending and chemical interesterifications are an effective way to modify the physical and chemical properties of palm stearin, palm olein and their blends. The mixture and chemical interesterification allowed obtaining fats with various degrees of plasticity, increasing the possibilities for the commercial use of palm stearin and palm olein.     

基于棕榈油软脂的甘油二酯油结晶特性研究

采用Lipozyme 435脂肪酶催化棕榈油软脂与甘油进行酯交换反应制得两种不同甘油二酯含量(62.7%与82.6%)的甘油二酯油。通过差示扫描量热仪、X射线衍射仪等表征了两种产品的熔化结晶特性和晶型等物理特性,并通过Avrami方程对其等温结晶动力学进行了研究。结果表明:脂肪酸组成相似而纯度不同的甘油二酯油,纯度高的甘油二酯油的熔点、结晶起始点均高于纯度低的甘油二酯油。非等温结晶中,两者表现出相似的热力学性质。等温结晶中,两者成核方式均为异相成核,但存在两种晶体生长机制。此外,高纯度的甘油二酯油较低纯度的甘油二酯油含有更多的β'晶型,形成的结晶网络更加细腻。     

棕榈油硬脂和大豆油酶法酯交换的研究

进行了固定化脂肪酶Lipozyme TL IM催化棕榈油硬脂和大豆油酶法酯交换的研究,考察了酶法酯交换分批操作的反应动力学曲线,发现5%的加酶量、70℃下反应,反应3 h内达到平衡,反应温度在70~90℃对反应速度无明显影响。采用填充床式反应器进行连续反应,结果表明通过装有10 g脂肪酶柱子的最佳流速为30 g/h。对化学酯交换和酶法酯交换产品性质的比较发现,二者SFC无明显差异。采用填充床式反应器对40∶60和30∶70的棕榈油硬脂和大豆油的混合物进行酶法酯交换反应,测定了反应产物的SFC曲线,为将来的应用开发提供参考数据。     

Flow properties of table margarine prepared from lipase-catalysed transesterified palm stearin:palm kernel olein feedstock

The flow properties of an experimental table margarine prepared from Rhizomucor miehei lipase-catalysed transesterified palm stearin:palm kernel olein (PS:PKO) blend at 40:60 was stored for 3 months at test temperatures of 20 and 30°C and determined using a controlled-rate rheometer. A commercial table margarine was used as a comparison. The shear stress-shear rate data was represented well by the Herschel–Bulkley model (r > 0.99). The mean yield stress values during storage were the highest for the experimental table margarine. However, the effect of storage on the mean yield stress was insignificant (p > 0.001). The Power Law model with a yield stress also represented the margarine flow well (r > 0.99) and the Power Law intercepts and slopes were also the highest for the experimental margarines, indicating a higher degree of firmness in the experimental samples. Storage effect was also insignificant (p > 0.05).     

Zero trans shortening using rice bran oil, palm oil and palm stearin through interesterification at pilot scale

Fat blends, formulated by mixing refined, bleached and deodorised (RBD) palm oil (PO) or RBD palm stearin (PS) with RBD rice bran oil (RBO) in various ratios were subjected to chemical interesterification (CIE) at pilot scale using sodium methoxide (NaOMe) as catalyst. The resultant interesterified fat was processed through a margarine crystalliser under optimised conditions. The blends before and after CIE were investigated for triacylglycerol (TAG) composition, solid fat content (SFC) and melting characteristics, polymorphic form, fatty acid composition (FAC), bioactive (tocols, sterols, oryzanol) constituents and trans fatty acids (TFA). CIE was found to be very effective in terms of rearrangement of fatty acids (FAs) among TAGs and consequent changes in the physical characteristics. The SFC of the interesterified PS/RBO blends decreased significantly ( P  ≤ 0.05) when compared with those of PO/RBO blends. The interesterified binary blends with 50–60% PS and 40–50% RBO, and 70–80% PO and 20–30% RBO had SFC curves in the range of all-purpose type shortenings. CIE facilitated the formation of β' polymorphic forms. FAC of shortenings prepared using the optimised blends contained 15–20% C_18:2 polyunsaturated fatty acid (PUFA) and no TFA. Total tocol, sterol and oryzanol content of zero trans shortenings were 650–1145, 408–17 583 and 1309–14 430 ppm. CIE using NaOMe did not affect the bioactive constituents significantly ( P  ≤ 0.05).     

Application of hydrogenated palm kernel oil and palm stearin in whipping cream

Non-dairy creams made from hydrogenated palm kernel oil (HPKO) are generally more stable than dairy creams. However, in summer the emulsion tends to separate. This paper outlines some steps that were taken to modify the HPKO with the intention of increasing the stability without affecting whipping performance. This was achieved by blending HPKO with palm stearin (POs). Interesterification was employed to eliminate the increase in solid fat content at 37°C and 40°C. Results of the experiment showed that an interesterified HPKO: POs 66:34 blend proved to have satisfactory whipping performance when compared to creams made with HPKO alone.     

Discrimination of the origin of commercial red ginseng concentrates using LC-MS/MS and electronic nose analysis based on a mass spectrometer

The geographical origin of commercial red ginseng concentrates was studied using LC-MS/MS and electronic nose analysis based on mass spectrometry. For LC-MS/MS, the Ra1, Rb1, Rg2 ginsenosides showed large differences between Korean and Chinese varieties. Rh2 and F2 were found only in Chinese red ginseng concentrate. Ion fragments were obtained using an electronic nose. Discriminant function analysis of fragment patterns allowed grouping into Korean, Chinese, and suspect origin concentrates. The mixing ratios of suspect origin specimens were predicted based on analysis of different mixing ratios of known specimens of Korean and Chinese origin. LC-MS/MS and electronic nose analysis together allowed method advantages and disadvantages to complement and compensate.     

亚麻籽油和棕榈液油煎炸油条过程中的品质变化

为了获得亚麻籽油的最适煎炸条件,在（180±5） ℃下,以GB 2716—2018中规定极性化合物含量达到27%为煎炸终点,对亚麻籽油和棕榈液油在油条连续煎炸过程中理化指标进行检测和比较,同时对油条进行感官评定。结果表明：在连续煎炸油条过程中,两种植物油的酸值、总氧化值、极性化合物及聚合物含量均随着煎炸时间的延长而不断增加,但在4 h以内,亚麻籽油极性化合物含量较低;亚麻籽油的极性化合物含量在煎炸13 h后达到27.78%,而棕榈液油的极性化合物含量在煎炸18 h后达到27.27%;相较于棕榈液油,在油条煎炸过程中,亚麻籽油中多不饱和脂肪酸含量不断减少,尤其是α-亚麻酸下降幅度更大;亚麻籽油140 ℃下的氧化诱导期均在1 h以内,远低于棕榈液油;油条感官评定表明棕榈液油更适宜于油条煎炸。研究表明亚麻籽油适合短时（<4 h）高温煎炸,不建议长时间深度煎炸。     

棕榈液油在调和油中应用研究

将熔点18℃棕榈液油分别与大豆油、菜籽油、玉米油和葵花籽油进行调配,得出不同季节条件下最佳调配比例;结果表明,棕榈液油作为一种调和油原料油,在春、夏、秋季均能应用于食用调和油。     

Scaled-up production of zero-trans margarine fat using pine nut oil and palm stearin

An interesterified structured lipid was produced with a lipid mixture (600 g) of pine nut oil (PN) and palm stearin (PS) at two weight ratios (PN:PS 40:60 and 30:70) using lipase (Lipozyme TL IM, 30 wt.%) as a catalyst at 65 ^°C for 24 h. Major fatty acids in the interesterified products were palmitic (35.1–40.4%), oleic (29.5%), and pinolenic acid (cis-5, cis-9, cis-12 18:3; 4.2–5.9%). α-Tocopherol (1.1–1.3 mg/100 g) and γ-tocopherol (0.3–0.4 mg/100 g) were detected in the interesterified products. Total phytosterols (campesterol, stigmasterol, and β-sitosterol) in the interesterified products (PN:PS 40:60 and 30:70) were 63.2 and 49.6 mg/100 g, respectively. Solid fat contents at 25 ^°C were 23.6% (PN:PS 40:60) and 36.2% (PN:PS 30:70). Mostly β′ crystal form was found in the interesterified products. Zero-trans margarine fat stock with desirable properties could be successfully produced from pine nut oil and palm stearin.     

棕榈硬脂大豆油相容性分析及调和性研究

以棕榈硬脂和大豆油为研究对象,采用ΔSFC分析两者的相容性,利用单因素实验和正交实验优化调和技术参数。结果表明,在考察的温度范围内棕榈硬脂和大豆油存在共晶现象,相容性较差,而使用卵磷脂、斯潘60和分子蒸馏单甘酯作为调和剂,能达到稳定的调和效果。调和剂的种类和添加量对调和油样的稳定性有显著影响,调和剂之间存有交互作用。在斯潘60添加量0.6g/kg、调和温度60℃、时间20min条件下,按照棕榈硬脂和大豆油1∶9的比例制备的调和油,常温存储稳定性较好,离心分离率为1.3%,氧化稳定性优于大豆油。      

Optimizing palm oil and palm stearin utilization for sensory and textural properties of chicken frankfurters

This study was designed to explore the potential of refined, bleached and deodorized (RBD) palm oil (PO) and palm stearin (POs) utilization in chicken frankfurters. A 10 points augmented simplex-centroid design was used to study the effect of chicken fat (CF), PO and POs as well as the interaction of these fats on the emulsion, textural and sensory properties of chicken frankfurters. All frankfurters were formulated to contain approx 25% fat, 52% moisture and 10% protein. No significant difference was found in end chopping temperatures of all meat batters even though the temperature of PO and POs upon incorporation into meat batters was 50°C higher than CF. Strong emulsions were formed as no fluid losses were observed in all the meat batters tested after heating. Texture profiles of the frankfurters containing PO and/or CF were quite similar, but increment of POs raised hardness, chewiness, and shear hardness of the frankfurters. Acceptability of the frankfurters was evaluated using hedonic test. Panelists found no difference in hardness preference between frankfurters made from totally CF and PO, while frankfurters made from POs were rated as hard and brittle. CF was important in determining acceptability of the frankfurters, as reduction of CF in formulation resulted in lower scores in chicken flavor, juiciness, oiliness and overall acceptance of the frankfurters. Frankfurters with sensory acceptability comparable to a commercial one were found to comprise of more than 17% CF, and less than 67% PO and 17% POs of the fat blend.     

Thermal behavior of concentrated oil-in-water emulsions based on soybean oil and palm kernel olein blends

Droplet size distribution and thermal behavior of concentrated oil-in-water emulsions based on soybean oil (SBO)/palm kernel olein (PKO) blends were investigated. The emulsions were prepared using 70% (wt./wt.) oil blends of SBO/PKO as dispersed phases and stabilized by egg yolk. An increase in PKO level (0–40% wt./wt.) in the oil dispersed phase volume fraction caused significant increases (p < 0.05) in volume-weighted mean diameter (d_4,3). The DSC data suggested that crystallization of the emulsions was induced by a ‘template effect’ of yolk constituents via a surface heterogeneous nucleation. Emulsions with 0–20% (wt./wt.) PKO levels in the dispersed phase demonstrated a good cool–heat stability even after three successive thermal cycles (from 50 °C to ?70 °C at 10 min/°C). After the first thermal cycle, emulsions with 30% and 40% PKO levels in the oil dispersed phase were destabilized due to strong coalescence and crystallized via volume-surface heterogeneous nucleation. The unstable emulsions were attributable to high level of saturated triacylglycerols from PKO, with high droplet size characteristic, causing them to be more prone to partial coalescence.     

核桃油与棕榈硬脂复配体系在涂抹脂基料油中的应用

对棕榈硬脂与核桃油复配体系的相容性及结晶性质变化进行探究,考察复配体系在涂抹脂基料油中的应用。结果表明,当核桃油含量达到20%以上时,复配体系的固体脂肪含量(Solid Fat Content,SFC)变化趋势符合涂抹脂的最佳SFC曲线特征,适合用作涂抹脂基料油;在温度高于33.3℃时,核桃油与棕榈硬脂在复配比例(1∶9、2∶8、3∶7、4∶6)下可以完全相容;在核桃油比例达到3∶7以上时,复配体系的屈服值符合涂抹脂的最佳屈服值范围;在温度低于30℃时,棕榈硬脂及复配体系具有较强的晶体网络结构,能在运输和贮藏过程中维持稳定的形态,在接近体温时也能快速熔化,产生涂抹脂类似的口感,复配体系中晶体以β′晶型为主。该结果为棕榈硬脂及核桃油复配体系在涂抹脂中的应用奠定基础。     

电子鼻对市售花椒油商品的鉴别

花椒油风味独特,是重要的川菜味型必备调味品。市售的花椒油质量参差不齐,品质鉴评主要依靠人为感官评价,主观影响较大。本文希望通过电子鼻技术的主成分分析法,探索花椒油质量快速检测的新方法。