By Dr. H C Sudeeksha
India is one of the largest producers of food and beverages products and has the potential to grow at a significant rate (CAGR ∼ 10%) over the next few years. Keeping in line with this rapid growth, there is a periodic influx of new products in the food and beverages market. The major challenges faced by this industry are to identify and estimate the nutritional value and adulteration in food and beverages products. We require appropriate food detection technologies which play a vital role in ensuring food safety in the supply chains. The conventional food component and adulterant detection methods like HPLC, GC-MS and LC-MS are labour intensive, expensive, time consuming and may alter food samples. We need alternative techniques which are non-destructive, easy to operate, rapid, inexpensive, and low levels of detection must be possible. All these considerations bring us to a specific question: can we use spectroscopy as a quality control tool? HORIBA Scientific has just the right technologies to address these problems in the food and beverages industry. HORIBA has been at the forefront of producing advanced instruments for a wide range of applications in various fields. In this context, we seek introduce the particle size analyzer and optical spectroscopy to tackle the afore-mentioned challenges.
Characterization of milk compounds by laser diffraction and Raman spectroscopy
The characterization of food components is a critical step to ensure the product quality or provide information to customers who are sensitive to allergies, especially for a specific product like milk. One of the main consumer and critical products in the market is milk. Milk can be characterized using a combination of particle size analysis and Raman spectroscopy. Each of these techniques provides information about milk chemical composition such as vitamins, fatty acids etc. The particle size analysis discussed in this article is based on laser diffraction. The principle of laser diffraction is that the particles scatter light at specific angles which will determine the particle size. Refer to our article published in the June 2023 edition of this magazine for a further understanding of the technique. The HORIBA Partica LA-960V2 stands out as the preferred instrument for measuring particles in the range 10 nm to 5 mm in both wet and dry modes.
The predominant particles present in milk are proteins (casein and others) and fatty acids. The expected particle size for proteins and fatty acids are 40 nm to 400 nm and 400 nm to 10 µm respectively.1 As shown in figure 2, the particle size range between 0.5 µm to 10 µm displays the level of fat i.e., fatty acid present in various types of milk available in the market. The presence of this range in the analysis indicates a first assessment of fat composition of milk samples. The lower values of particle size provide a qualitative analysis of casein micelles.
Figure 2. a) Particle size distribution of different cow milks. b) Raman spectra of five different milk samples. c) Correlation curve – Raman band intensity at 2875 cm-1 vs theoretical fat.
Particle size analysis offers valuable qualitative information about the composition of milk samples, but to understand the chemical composition Raman spectroscopy is essential. Raman spectroscopy is a non-destructive technique which provides detailed information about chemical structure, crystallinity, and molecular interactions. HORIBA XploRA Plus Raman microscope is suitable for understanding the chemical composition. The Raman spectra of five milk samples are shown in figure 2. The spectra were recorded in 1s for each sample. These spectra are a mixture of fatty acids (2600-3100 cm-1) and water (3150-3600 cm-1). The linear correlation reveals that high intensity of fatty acid Raman band is associated with high content of fats. So, particle sizing technique along with Raman spectroscopy can be used to understand the properties of milk.
A-TEEM molecular fingerprinting for classification and phenolics analysis of red wine
A-TEEMTM molecular fingerprinting is a HORIBA patented technology. This method employs simultaneous detection of Absorbance-Transmission and Fluorescence Excitation Emission Matrix spectroscopy. It is rapid analysis technique with high throughput and low levels of detection. Aqualog and Duetta are two instruments from HORIBA which can measure the A-TEEM spectra. The A-TEEM data along with the Multivariate Analysis (MVA) tools like Classical Least Squares (CLS) is a potent analytical tool for quality control assessment.
The quality of wine is fundamentally determined by the phenolic content of the ripening grape berries. The different classes of phenolics (anthocyanins, tannins, catechins) affect the colour, mouthfeel, flavour, and aroma to various extent.2 The individual components and their respective compositions give wines their unique character. A-TEEM is a useful technique to both identify and quantify the components. The A-TEEM spectra shown in figure 3 reveals a unique fingerprint for different wine brands depending on the differences in the basic components. The CLS analysis of the A-TEEM spectra shows the differences in composition.
Figure 3. Left: The A-TEEM spectra of different brands of Red Wines. Right: Composition of each Red Wine determined by CLS analysis.
Traditional analysis of food and beverages depends on the use of HPLC, GC-MS and LC-MS techniques which requires sophisticated laboratory instruments and expert sample preparation by trained personnel. On the contrary, the HORIBA Scientific instruments are simple, easy-to-use, and inexpensive techniques which are equipped with software capabilities to perform quality control analysis rapidly. We can quite strongly conclude that the question that we sought to answer at the beginning of the article: whether we can use spectroscopy as a QC tool in food and beverages industry, has been answered in an affirmative.
- Brule, T. et al. Application Note, Multitechniques AN04, HORIBA Scientific, France
- Waterhouse et al. Understanding wine chemistry ed. Wiley and Sons (2016)
Contact details: Dr. H C Sudeeksha, email@example.com
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About the Author
Applications Scientist, HORIBA India Scientific