Detection of possible adulteration in commercial ghee samples using low-resolution gas chromatography triglyceride profiles

Detection of soybean oil adulteration in cow ghee (clarified milk fat): an ultrafast study using flash gas chromatography electronic nose coupled with multivariate chemometrics

BACKGROUND

Cow ghee is one of the expensive edible fats in the dairy sector. Ghee is often adulterated with low-priced edible oils, like soybean oil, owing to its high market demand. The existing adulteration detection methods are time-consuming, requiring sample preparation and expertise in these fields. The possibility of detecting soybean oil adulteration (from 10% to 100%) in pure cow ghee was investigated in this study. The fingerprint information of volatile compounds was collected using a flash gas chromatography electronic nose (FGCEN) instrument. The classification results were studied using the pattern recognition chemometric models principal component analysis (PCA), soft independent modelling of class analogy (SIMCA), and discriminant function analysis (DFA).

RESULTS

The most powerful fingerprint odor of all the samples identified from FGCEN analysis was acetaldehyde (Z)-4-heptenal, 2-propanol, ethyl propanoate, and pentan-2-one. The odor analysis investigation was accomplished with an average analysis time of 90 s. A clear differentiation of all the samples with an excellent classification accuracy of more than 99% was achieved with the PCA and DFA chemometric methods. However, the results of the SIMCA model showed that SIMCA could only be used to detect ghee adulteration at higher concentration levels (30% to 100%). The validation study shows good agreement between FGCEN and gas chromatography-mass spectrometry methods.

CONCLUSION

The methodology demonstrated coupled with PCA and DFA methods for adulteration detection in ghee using FGCEN apparatus has been an efficient and convenient technique. This study explored the capability of the FGCEN instrument to tackle the adulteration problems in ghee. © 2022 Society of Chemical Industry.

Simple chromogenic test for detection of adulterated milk with vegetable oil at village milk collection center- A preliminary study

In the present investigation, a novel chromogenic test has been developed to ascertain the presence of vegetable oil in milk. This standardized protocol did not show any false-positive results in the genuine milk samples. Adulteration of milk with vegetable oil @ 1% level could be detected by this chromogenic test protocol. This said protocol is convenient to use in the rural dairy industry especially rural-based milk collection centers; as no costly instrument or trained manpower is required for this said test.

A barcode-DNA analysis method for the identification of plant oil adulteration in milk and dairy products

In the present work, a barcode-DNA analysis method is described for the detection of plant oil adulteration in milk and dairy products. The method relies on the fact that plant DNA should not be present in readily detectable amounts in a dairy product unless it contains undeclared plant material. Thus, a universal plant barcode is chosen as the target to be amplified from dairy samples. Accordingly, barcode PCR-CE (PCR-capillary electrophoresis) assays are described, which do not require preliminary information on the species source of the adulterant oil type. Two PCR-CE assays, one operating on the plastid trnL (UAA) intron and the other targeting its inner P6 loop in nested format, were shown to detect corn, soybean, rapeseed and sunflower oils in clarified butter, milk and yogurt. Both barcodes are robustly amplified with extremely conserved primers. While the intron provides the species discrimination ability, the P6 loop provides superior detection sensitivity.

A novel approach to detect highly manipulated fat adulterant as Reichert-Meissl value-adjuster in ghee (clarified butter) through signature peaks by gas chromatography of triglycerides

Ghee, the clarified butter fat being the costliest fat among other edible oils and fats in India, prone to adulteration with highly manipulated cheaper oils/fats, especially during lean season. The present investigation carried on triglycerides profile of one of the latest components of the adulterant fat i.e. RM (Reichert-Meissl)-adjuster, has been exploited to check the adulteration of ghee with a newly emerged highly manipulated fat. Using standardized (S)-limits specified by the ISO/IDF for cow milk fat, the minimum level of detection of the adulterant fat was observed as 7.5%. However, in case of buffalo ghee, due to non-availability of the ISO/IDF limits, the detection of this adulterant fat in buffalo ghee was not possible. Gas chromatograms showed specific signature peaks of large size in the retention time region of 4.5 to 6.5 min for RM-adjuster and adulterant fat, whereas no such peaks were observed in pure cow and buffalo ghee samples. The new approach of zooming in and superimposing of selected peaks in the chromatograms of triglycerides of suspected ghee has been used as a strategy to find adulterant fat's presence. Through this approach, the addition of RM-adjusted highly manipulated foreign fat (adulterant fat) to the tune of even 0.5% could be achieved in both cow as well as buffalo ghee.

Detection of goat body fat adulteration in pure ghee using ATR-FTIR spectroscopy coupled with chemometric strategy

Ghee forms an important component of the diet of human beings due to its rich flavor and high nutritive value. This high priced fat is prone to adulteration with cheaper fats. ATR-FTIR spectroscopy coupled with chemometrics was applied for determining the presence of goat body fat in ghee (@1, 3, 5, 10, 15 and 20% level in the laboratory made/spiked samples). The spectra of pure (ghee and goat body fat) and spiked samples were taken in the wavenumber range of 4000-500 cm^-1. Separated clusters of pure ghee and spiked samples were obtained on applying principal component analysis at 5% level of significance in the selected wavenumber range (1786-1680, 1490-919 and 1260-1040 cm^-1). SIMCA was applied for classification of samples and pure ghee showed 100% classification efficiency. The value of R² was found to be >0.99 for calibration and validation sets using partial least square method at all the selected wavenumber range which indicate that the model was well developed. The study revealed that the spiked samples of goat body fat could be detected even at 1% level in ghee.

Determination of triacyl glycerol and sterol components of fat to authenticate ghee based sweets

Method comparison of triacyl glycerol (TAG) and sterol components of fats of ghee based sweets was carried out on dairy ghee, laboratory prepared control sample and market samples. The fat was extracted from control and market samples. Determination of TAG and sterol composition of the fats was carried out using low resolution Gas Chromatography. The quantification of cholesterol and β-sitosterol and TAG classes of dairy ghee, control and market samples fat was also determined using single short column. Adulteration at 5 % level in milk fats showed varied TAG compositions of C50, C52 and C54 as compared to control and pure ghee sample. The cholesterol content of ghee and control sample was 2.30 ± 0.8, 2.00 ± 0.24 g/kg respectively and β-sitosterol content of control was 0.20 ± 0.11 g/kg. The adulterated samples showed varied cholesterol and β-sitosterol contents as compared to control sample fat.

A rapid reversed-phase thin layer chromatographic protocol for detection of adulteration in ghee (clarified milk fat) with vegetable oils

Detection of milk fat adulteration with foreign fats/oils continues to be a challenge for the dairy industry as well as food testing laboratories, especially in the present scenario of rampant adulteration using the scientific knowledge by unscrupulous persons involved in the trade. In the present investigation a rapid reversed-phase thin layer chromatographic (RP-TLC) protocol was standardized to ascertain the purity of milk fat. RP-TLC protocol did not show any false positive results in the genuine ghee (clarified butter fat) samples of known origin. Adulteration of ghee with coconut oil up to 7. 5 %, soybean oil, sunflower oil and groundnut oil up to 1 %, while, designer oil up to 2 % level could be detected using the standardized RP-TLC protocol. The protocol standardized is rapid and convenient to use.