Research paper: Journal of Raman Spectroscopy 57(10), online 29 May 2026 (Crossref metadata; print issue October 2026) • News: The Hindu, 31 May 2026
Prelims • Science and Technology: Food safety and analytical chemistry
Why in the News
According to The Hindu (31 May 2026), researchers of IIT (BHU), Varanasi showed that fake ghee can be made by adding a carotenoid-rich carrot extract to pig fat (lard) or palm oil, which can fool the popular Raman spectroscopy test for identifying cow ghee. According to the press, this finding, based on a small sample size, raises two questions: concern about fraud in India's premium dairy market, and the effectiveness of this quick test widely used in regulatory laboratories.
The Key Point to Remember:
In earlier studies, three Raman peaks of beta-carotene - 1006, 1157 and 1520 cm⁻¹ - were considered reliable markers of cow ghee. According to the paper, the same peaks can be produced in non-dairy fat with carrot extract; the lowest detection limit was 0.22 mg/g (0.022% w/w). According to the authors, authentication relying only on these peaks is "highly vulnerable".
Fake ghee from carrot extract
J. Raman Spectroscopy 57(10); news: The Hindu 31 May 2026
Method
Lard/palm oil + beta-carotene extract → ghee-like Raman peaks
Marker peaks
1006, 1157, 1520 cm⁻¹ (standards of earlier studies)
Limit/complement
LOD 0.22 mg/g; fat unchanged in ATR-FTIR
Diagram: original table.
What Is in the Paper?
It is in the paper "Carotenoid-Fortified Lard Mimics Cow Ghee in Raman Spectra" (Vineet Sharma, Ajay Kumar Bind, Shreyans K. Jain, Venkatanarayanan Ramanathan; Journal of Raman Spectroscopy 57(10); DOI: 10.1002/jrs.70180; online 29 May 2026 according to Crossref metadata). Cow ghee naturally contains beta-carotene, which gives it its yellow colour; from here this testing tradition arose. According to the abstract, the researchers mixed a carotenoid extract taken from carrot (qualitatively confirmed by HPLC at 453 nm) into lard and palm oil - the Raman spectra of both became similar to that of cow ghee, and the colour also became yellow-orange.
According to the abstract, in a controlled dilution series (Master-LC21) the prominence of the carotenoid band fell systematically as lard was increased, and the lowest detection limit was 0.22 mg/g (0.022% w/w in lard). In the complementary ATR-FTIR analysis only lipid signatures were found; the carotenoid peaks were invisible in it - that is, Raman is essential to catch the beta-carotene peaks, but the structure of the fat had not changed: the similarity was only of the added pigment. According to the authors, the study is an "anti-fraud proof-of-concept", not a survey of adulteration of real ghee; authentication relying only on the beta-carotene peaks is "highly vulnerable". According to the press, Raman spectroscopy is named after Nobel laureate C.V. Raman and verifies structure like a molecular fingerprint.
Where Does Confusion Arise in the Exam?
The three peaks (1006/1157/1520 cm⁻¹) are markers of earlier studies, not a discovery of this paper - this paper showed their fragility. Carotenoid peaks were not seen in ATR-FTIR (only lipid signatures were found) - it would be wrong to say that FTIR showed ghee similarity. 0.22 mg/g = 0.022% w/w (in lard, Master-LC21 series); this is a laboratory detection limit, not a regulatory safety limit. The study did not test adulteration of real ghee in the market; the conclusion is about the fragility of the test, not the scale of market adulteration. A fat mixed with carrot extract does not become nutritious or dairy - the similarity is spectral and of colour. Dates: paper online 29 May 2026 (Crossref metadata), news 31 May 2026.
Direction of Preparation from Past Questions:
In the official Prelims 2023 Paper-I of UPSC, statement-based questions have come; prepare technique names, peak values and the scope of the study separately. The questions below are original practice, not actual PYQs.
Prelims Style: Practice Questions
1. On the basis of the paper, consider the following statements:
Statement 1: On adding carrot extract, the Raman spectra of lard and palm oil became similar to those of cow ghee.
Statement 2: Carotenoid peaks were clearly visible in the ATR-FTIR analysis.
Statement 3: The study was designed as an "anti-fraud proof-of-concept".
Which of the statements given above is/are correct?
(a) Only Statement 1
(b) Only Statements 1 and 3
(c) Only Statements 2 and 3
(d) All three statements
See answer and reason
Answer: (b) Only Statements 1 and 3. Statement 2 is wrong: only lipid signatures were found in ATR-FTIR, the carotenoid peaks stayed invisible - that is why Raman was stated to be essential for the beta-carotene peaks.
2. Which are the Raman peaks of beta-carotene considered markers of cow ghee in earlier studies?
(a) 1006, 1157 and 1520 cm⁻¹
(b) 453, 721 and 1100 cm⁻¹
(c) 2200, 3400 and 3650 cm⁻¹
(d) 57, 110 and 226 cm⁻¹
See answer and reason
Answer: (a). 1006, 1157 and 1520 cm⁻¹. (453 nm is the wavelength of the HPLC confirmation of the carrot extract, not a Raman peak; 57(10) is the issue of the journal.)
3. What was the lowest detection limit of the carotenoid extract in the Master-LC21 dilution series?
(a) 0.22 mg/g (0.022% w/w)
(b) 2.2 mg/g (0.22% w/w)
(c) 22 mg/g (2.2% w/w)
(d) 0.022 mg/g (0.0022% w/w)
See answer and reason
Answer: (a). 0.22 mg/g = 0.022% w/w (in lard). Number conversion: 0.22 mg per 1000 mg = 0.00022 = 0.022%.
Sources:
J. Raman Spectroscopy 57(10): research paper (abstract from Crossref/Wiley metadata) • The Hindu: fake ghee from carrot extract, 31 May 2026 • UPSC Prelims 2023 question paper.
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