The Importance of UV-Vis Spectroscopy: Application in Food Products Characterization

Prisna JS Leder and Ornella Maria Porcu*

• Department of Chemistry, Federal University of Technology-Paraná (UTFPR), Campus Medianeira /PR, Brazil

Received: May 30, 2018;   Published: June 08, 2018

*Corresponding author: Ornella Maria Porcu, Department of Chemistry, Federal University of Technology-Paraná (UTFPR), Campus Medianeira /PR, Post Graduation Program of Chemical and Biochemical Process (PPGTP), Pato Branco/PR, Brazil

DOI: 10.32474/SJFN.2018.01.000111

Abstract PDF

There is a great concern about the quality of food products in the current market, since adulterations of them can lead to financial loss and damages to consumer health. In this context, the techniques for food characterization have been useful tools, specially the spectroscopic techniques, since they do not destroy the sample under analysis nor do they produce toxic residues. One of these techniques is the absorption spectroscopy in the Ultraviolet and Visible region, which is used for qualitative and quantitative characterization of sample compounds. This study is a bibliographical review that seeks to demonstrate the effectiveness and relevance of using this technique in food products characterization. Therefore, a bibliographic survey of publications in national and international journals in the last eight years was carried out.

All the analytical techniques used to collect physicochemical data obtained by absorbing, transmitting or reflecting the incident radiant energy in a sample are called spectrophotometry [1]. Among these analytical techniques, there is the light absorption spectroscopy in the Ultraviolet and Visible region (UV-Vis) (200- 800nm) as one of the most used technique for the characterization and determination of several organic and inorganic substances [2]. The UV-Vis analytical method has become very important and widespread in different scientific areas around the world due to its availability, simplicity, flexibility and wide applicability in several areas, including biochemistry and analytical chemistry. Currently, it is necessary to reduce sample and reagents quantity to develop an analytical measurement, especially for scarce samples or toxic solvents; therefore, a UV-Vis microvolume spectrometric instrumentation has been developed [3].

Currently, spectroscopy techniques and chemometric methods are largely used in the food industry analyses to improve quality control of foods and beverages, such as: detection of falsification or adulteration, identification of origin [4], differentiation of caffeinated and decaffeinated coffee, origin and variety of wine or the origin of olive oils [5], and others. This study presents a bibliographic review in order to evaluate the effectiveness and the relevance of using the analytical technique of molecular spectrophotometry in the Ultraviolet and Visible region in the food industry.

The literature survey was carried out through searches in ScienceDirect journal portal (www.sciencedirect.com), which provided nine international paper, by using the following search terms: “Use of UV-Vis spectroscopy in food” and “Application of UVVis spectroscopy in food analysis”. These search terms were also used in the CAPES journal portal (www.periodicos.capes.gov.br) and one national paper was also selected. The collected papers were published in the last eight years in order to maintain the updated data. The parameters analyzed in the paper are presented in Table 1: The study objectives, the methodology applying UV-Vis analysis, and the main results. It could be noted various objectives of using UV-Vis spectroscopy in food industry, highlighting the analyses to identificate possible frauds in general foods and beverages.

Table 1 presents ten papers selected in the bibliographic survey, describing the objectives of the authors, the methodology used to reach these objectives and the main results obtained in the studies. Problems involving food adulteration can be identified in two ways: using quantitative analysis, when the adulterant is known,otherwise, the qualitative analysis is able to provide satisfactory results. The qualitative methods such as UV-Vis, for example, have been highlightly applied in quality control of food and beverages, and they have increasingly attracted interest due to their screening potential, which allows the identification of possible frauds that may occur in food products [6].

Table 1: Relação dos artigos selecionados por meio de levantamento bibliográfico (2010-2017).

Source: Author, 2018.

According to Darra, et al. [7] food fraud is a serious ethical and economic problem that affects food industries around the world. In their study, the determination of frauds occurrence in pomegranate molasses syrup was performed using polyphenol characteristics such as its diversity, quantity and bioactivity. The UV-Vis spectroscopy was used as a screening method to determine the adulteration level of pomegranate molasses with date syrup, the HPLC was used to perform an identification of sample adulterants, and ATR-FTIR provided an additional evidence for the perceived differences in the analyzed samples.

In the study accomplished by Martins, et al. [4] the UV-Vis technique was used in order to identify counterfeit Whiskey, which is an high value alcoholic beverage and widely commercialized. It has been constantly adulterated with the substitution with another whiskey of lower quality using the original commercial bottle. The UV-Vis spectroscopy technique was combined with partial least squares for discriminant analysis (PLS-DA), which showed great efficiency in the discrimination of different brands and identify adulteration such as dilution and mixing.

The UV-Vis technique has a very wide application also in vegetable oils, this can be validated by four papers showed in Table 1. One of these studies was developed by Milanez, et al. [8] who verified the adulteration of extra virgin olive oil with soy oil. The results showed the screening approach as very promising, and could support other official analytical methods currently used to identify adulterations in oils. One of the most important concern related to food adulteration is the possible risk for consumer health or an economic benefit. Olive oil has high nutritional value and pleasant sensory characteristics and also a higher commercial value than common oils, therefore, olive oil is constantly adulterated with the addition of vegetable oils with lower quality [9].

Coffee is one of the most consumed beverages in the world, due to its intrinsic characteristics, stimulant property and some benefits to health. The variety of coffee types is relatively large, due to this, the normative instruction n. 16 of Ministry of Agriculture, Livestock and Food Supply (MAPA) has established a maximum limit of 1 g/100 g for some impurities (stones, peels, stick) in roasted coffee, in order to avoid illegal practices of adulteration [10-18]. In this context, Souto, et al. [19] used UV-Vis spectroscopy associated with linear descriptive analysis to identify irregularities in coffee extracts. According to authors, the technique presented advantages over other methods normally used for this kind of analysis because it provided a simple and quick analysis of coffee extracts, besides it may offer safety to consumers and regulatory agencies, avoiding fraudulent labeling of these products. The bibliographic survey carried out in this study showed a great concern of food industries to use analytical methods that present easy access, low cost, simplicity and reliable experimental parameters. Among these analytical techniques, the UV-Vis spectroscopy congregates numerous and important methodologies applied in the improvement of food products quality control.

The spectroscopy in the visible ultraviolet region is a very useful technique for qualitative and/or quantitative studies related to characterization of organic and inorganic compounds in food matrices. In this context, the scientific community has used this technique in several research areas of food science and technology sector; its application in quality laboratories of food industries has been very important, because it satisfies both the economic scope and the public health issues, since it allows the quality verification of various products widely commercialized and consumed around the world.

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