Potential of Near-Infrared Fourier Transform Raman Spectroscopy in Food Analysis

Authors: Ozaki, Y.1; Cho, R.2; Ikegaya, K.3; Muraishi, S.4; Kawauchi, K.4

Source: Applied Spectroscopy, Volume 46, Issue 10, Pages 1447-1592 (October 1992) , pp. 1503-1507(5)

Publisher: Society for Applied Spectroscopy

Buy & download fulltext article:

OR

Price: $29.00 plus tax (Refund Policy)

Abstract:

The 1064-nm excited Fourier transform (FT) Raman spectra have been measured in situ for various foods in order to investigate the potential of near-infrared (NIR) FT-Raman spectroscopy in food analysis. It is demonstrated here that NIR FT-Raman spectroscopy is a very powerful technique for (1) detecting selectively the trace components in foodstuffs, (2) estimating the degree of unsaturation of fatty acids included in foods, (3) investigating the structure of food components, and (4) monitoring changes in the quality of foods. Carotenoids included in foods give two intense bands near 1530 and 1160 cm−1 via the pre-resonance Raman effect in the NIR FT-Raman spectra, and therefore, the NIR FT-Raman technique can be employed to detect them nondestructively. Foods consisting largely of lipids such as oils, tallow, and butter show bands near 1658 and 1443 cm−1 due to C=C stretching modes of cis unsaturated fatty acid parts and CH2 scissoring modes of saturated fatty acid parts, respectively. It has been found that there is a linear correlation for various kinds of lipid-containing foods between the iodine value (number) and the intensity ratio of two bands at 1658 and 1443 cm−1 (I 1658/I 1443), indicating that the ratio can be used as a practical indicator for estimating the unsaturation level of a wide range of lipid-containing foods. A comparison of the Raman spectra of raw and boiled egg white shows that the amide I band shifts from 1666 to 1677 cm−1 and the intensity of the amide III band at 1275 cm−1 decreases upon boiling. These observations indicate that most α-helix structure changes into unordered structure in the proteins constituting egg white upon boiling. The NIR FT-Raman spectrum of old-leaf (about one year old) Japanese tea has been compared with that of its new leaf. The intensity ratio of two bands at 1529 and 1446 cm−1 (I 1579/I 1446), assignable to carotenoid and proteins, respectively, is considerably smaller in the former than in the latter, indicating that the ratio is useful for monitoring the changes in the quality of Japanese tea.

Keywords: Carotenoid; FT spectroscopy; FT-Raman; Fatty acids; Food analysis; Near-infrared; Proteins; Raman spectroscopy

Document Type: Research Article

DOI: http://dx.doi.org/10.1366/000370292789619368

Affiliations: 1: Department of Chemistry, School of Science, Kwansei Gakuin University, Nishinomiya 662, Japan 2: Department of Agricultural Chemistry, College of Agriculture, Kyungpook National University, Taegu 702-701, Korea 3: Harada Green Tea Co., Ltd., Shimada 427, Japan 4: Analytical Instruments Division, JEOL Ltd., Akishima 196, Japan

Publication date: October 1, 1992

More about this publication?
Related content

Tools

Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content

Text size:

A | A | A | A
Share this item with others: These icons link to social bookmarking sites where readers can share and discover new web pages. print icon Print this page