Use of gas chromatography in combination with pancreatic lipolysis and multivariate data analysis techniques for identification of lard contamination in some vegetable oils

A study was conducted to investigate the use of gas liquid chromatography (GLC) to identify lard contamination in palm oil (PO), palm kernel oil (PKO), and canola oil (CLO). Vegetable oils were deliberately adulterated with animal fats such as lard (LD), beef tallow (BT), and chicken fat (CF) in varying proportions. In order to monitor the fatty acid (FA) compositional changes due to adulteration, GLC analysis of fatty acid methyl esters (FAME) were performed on 2-monoacylglycerol (2-MG) and neutral triacylglycerol (TAG) isolated from each sample. For the evaluation of FA data, multivariate statistical techniques were employed. The results showed that canonical discriminant (CANDISC) analysis was the most effective technique in discriminating lard adulterated series from those adulterated with other animal fats. Additionally, mathematical equations obtained by simple regression analysis could be used for quantification of lard content in admixtures

DSC as a valuable tool for the evaluation of adulteration of oils and fats

Authentication is part of quality assessment to maintain purity standards in oils and fats. It is highly useful for oils and fats as it helps to combat adulteration practices taking place in trade and industries. Among the different analytical techniques, DSC is a valuable tool for establishing identity of pure oils and fats for authentication purposes. It is nondestructive technique and works with minimal sample preparation. DSC analyses of palmitic, lauric, and oleic oils can provide well-defined thermal curves, which can be compiled as a data base to become a reference for investigations leading to detection of adulterations. As DSC curves of plant oils and fats differ considerably from those of animal fats, adulterations in plant oils and fats caused by animal fats can be detected easily. There is basis for detection of adulteration qualitatively, if significant deviations are noticed in the DSC curve of a particular oil or fat with respect to that of the reference authentic sample. However, based on the characteristic composition of individual oil and fat, the detection approaches and limits of detection for either LD or BF differ considerably. DSC could also be used effectively for quantification of adulterations as DSC variables associated with adulteration peaks were found to show high correlation with the increasing levels of adulteration. For most oils, predictive models for estimation of lard adulteration can be obtained using stepwise multiple linear regression (SMLR) analysis with % LD (adulteration level) as the dependent variable and DSC parameters (peak area, A; peak height, HT; and peak onset, ON) of adulteration peak as independent variables

Effect of Moringa oleifera oil blending on fractional crystallization behavior of palm oil.

The objective of this study was to see the effect of Moringa oleifera oil blending on the fractional crystallization behavior of palm oil. Palm oil blended with Moringa oleifera oil at 20% (w/w) was subjected to crystallization using a dry process at 21 and 18°C and a solvent process at 15 and 10°C. After recording the quantitative recoveries of the liquid and solid fractions, their fatty acid and triacylglycerol compositions, and the thermal profiles were determined by using gas liquid chromatography, high performance liquid chromatography, and differential scanning calorimetry, respectively. Results showed that the yield recoveries of liquid fractions under solvent-assisted crystallization were higher than those obtained by dry-crystallization conditions. Almost all of the liquid fractions isolated had experienced a significant (p < 0.05) increase in oleic acid as well as triolein contents. Among the solid fractions, those isolated by dry-crystallization were found to be higher (p < 0.05) in oleic acid and triolein contents than the reference stearin sample. Although the thermal profiles of the solid and liquid fractions derived by different methods looked similar to those of the two reference samples, remarkable differences were noticed with regard to the onset of crystallization and the position of the thermal transitions

Differentiation of pork from other meat species by lipid analysis methodologies

A study was conducted to establish various lipid analysis methodologies to differentiate pork from other meat species such as cow, lamb, and chicken for halal authentication purposes. Extraction of lipids from meat species was done using a chloroform–methanol mixture according to the methodology of Folch et al. (1957). The isolated lipid samples were analyzed using instrumental techniques such as gas liquid chromatography (GLC), reversed-phase high performance liquid chromatography (RP-HPLC), elemental analyzer–isotope ratio mass spectrometry (EA-IRMS), and differential scanning calorimetry (DSC). According to GLC, lard and chicken fat shared common characteristics by having palmitic, oleic and linoleic acid as major fatty acids while beef and mutton fats shared common characteristics by possessing palmitic, stearic and oleic acid as major fatty acids. As direct comparisons among the fatty acid data may not be suitable for discrimination of different animal fats, the percent palmitic acid enrichment factor [PAEF (%)] was found to be very much useful to differentiate lard from other meat species. RP-HPLC analysis showed that triacylglycerol profile of lard was quite different from that of beef fat, but appeared to be closely related to that of chicken fat. Because of this, some peak ratios based on stearoyl-palmitoyl-oleoyl glycerol (SPO), linoleoyl-palmitoyl-oleoyl glycerol (LPO) and dioleoyl-palmitoyl glycerol (OPO) were found to be useful parameters to differentiate lard from other meat species. According to EA-IRMS analysis, determination of the carbon isotope ratios (δ13C) would be a good indicator for discriminating lard from other animal fats. In the DSC analysis, lard displayed cooling and heating profiles which were completely different from those of other animal fats. In conclusion, all these techniques provide some basis for halal authentication of meat species, and one technique can become a confirmatory to another technique

Distinguishing coconut oil from coconut pairing oil using principle component analysis of fatty acid data.

A study was carried out to distinguish coconut oil from coconut pairing oil by the application of principal component analysis (PCA) to fatty acid compositional and iodine value data. Five samples of ordinary coconut oil extracted from five different batches of copra and five samples of coconut pairing oil obtained from five batches of dried coconut pairings were employed. Fatty acid composition and iodine values of oil samples were determined individually and the data were analyzed statistically. PCA analysis showed that lauric and oleic acid contents and iodine value data are the most influencing parameters to discriminate coconut oil from coconut pairing oil. Hence, the application of PCA to fatty acid compositional and iodine value data was successful in distinguishing coconut oil from coconut pairing oil

Effect of varietal differences on composition and thermal characteristics of avocado oil.

A study was carried out to compare the characteristics of oils from three Malaysian avocado (Persea americana) cultivars with those of the oil from the Australian Hass avocado variety. Oil samples extracted from matured-avocado fruits were assessed for basic physico-chemical parameters, fatty acid and triacylglycerol (TAG) compositions, and melting and solidification characteristics. In comparison to Hass variety, the oil contents of the local avocado cultivars were significantly lower and found to be mostly in semisolid form. As a common feature, oils of both local cultivars and Hass variety are found to have oleic acid as the most dominant fatty acid. However, there are differences between them with regard to the proportional distributions of palmitic and linoleic acids. While the major TAG of local avocado cultivars were POO, followed by POL, OOO and PPO, the dominant TAG of Hass variety were OOO, followed by PPO, OOL and POL. Due to these differences in fatty acid and TAG distributional patterns, the oils of local avocado cultivars are found to possess iodine value, slip melting point, melting and solidification characteristics, which are completely different from those of the imported Hass avocado variety

Analytical approaches for discriminating native lard from other animal fats

Establishing the distinguishable characteristics of lard from other common animal fats might be helpful for authentication initiatives in foods and feeds. In this study, fatty acid and triacylglycerol compositions, thermal and spectroscopic characteristics of native lard (NL), respectively, were compared with those of beef tallow (BT), mutton tallow (MT), and chicken fat (CF) by using gas liquid chromatography (GLC), high-performance liquid chromatography (HPLC), and differential scanning calorimetry (DSC). GLC analysis showed that the comparison of the overall fatty acid data might not be suitable for the discrimination of different animal fats, but the use of the principal component analysis and the percent palmitic acid enrichment factor [PAEF (%)] calculations were useful. HPLC analysis showed that NL displayed a TAG profile, which was quite different from those of either BT or MT, but appeared to be closely similar to that of CF. Results of DSC thermal analysis showed that both melting and crystallization curves of NL were remarkably different from those of other animal fats

Effect of chemical and enzymatic modifications on the identity characteristics of lard: a review

Lard is a fat substance extracted from the adipose tissues of swine. Due to its specific physical and functional characteristics, lard has found numerous uses in the food and feed industry. Lard has often been subjected to modification through techniques, such as fractionation, partial hydrogenation, and interesterification. Although the application range of lard in food would have widened, these modification techniques could also change the original identity characteristic properties of lard, which enable its detection in food by various analytical methods. The purpose of this review is to present an update of the current literature in this topic and provide some directions for future research

Composition and thermal characteristics of Madhuca longifolia seed fat and its solid and liquid fractions

This study was to characterize the seed fat from Madhuca longifolia known as Mee fat and its solid and liquid fractions with the objective of distinguishing them. A sample of Mee fat was partitioned into solid and liquid fractions using acetone as the solvent medium. The isolated fractions were compared to the native Mee fat sample with respect to various physico-chemical parameters using standard chemical methods as well as instrumental techniques such as, gas liquid chromatography (GLC), reversed-phase high performance liquid chromatography (RP-HPLC), and differential scanning calorimetry (DSC). Basic analyses indicated that there were wide variations between the native sample and its fractions with respect to iodine value (IV), and slip melting point (SMP). The cloud point (CP) of the liquid fraction was found to be 10.5 degrees C. Fatty acid compositional analyses showed that the proportion of saturated fatty acids (SFA) such as palmitic and stearic went up in the high-melting fraction (HMF) while in low-melting fraction (LMF) the proportion of unsaturated fatty acid (USFA) such as oleic and lenoleic increased. According to the HPLC analyses, Mee fat had a tiacyl glycerol (TAG) sequence similar to that of palm oil. After fractionation, the solid and liquid fractions obtained were found to have TAG profiles very much different from the native sample. Thermal analyses by DSC showed that Mee fat had two-widely separated high and low melting thermal transitions, a feature which was beneficial for the effective separation of solid and liquid fractions. The thermal profiles displayed by the fractions were clearly distinguishable from that of the native sample