# Identification and Evaluation of Composition in Food Powder Using Point-Scan Raman Spectral Imaging
## 1 Introduction  
Food authentication is important in food supply chain operations, as illustrated by various incidents of food fraud that have caused public outcry around the world, raised public concerns, and highlighted the need for effective ingredient authentication methods. The toxic addition of melamine to dairy products and infant formula for the purpose of counterfeiting protein content was a high profile example of economically motivated food adulteration that posed significant health risks. Other forms of food fraud can include products that may be safe but have been made with ingredients omitted from product labels, as well as products whose labels over represent the content of desirable or costly ingredients. A variety of highly accurate analytical methods, such as DNA-based methods [1], polymerase chain reaction [2], mass spectrometry [3], and gas and liquid chromatography [4], can be used for food authentication but are limited in practical application due to high operational costs, long sampling times, and limited sampling volumes. Alternatively, interest in the development and use of non-destructive optical analysis methods for food safety and quality applications has been increasing due to their greater simplicity, lower operational costs, and suitability for rapidlyanalyzing larger sample volumes for a variety of safety and quality parameters. Optical spectroscopy and imaging techniques have been used for a variety of food safety and quality inspection applications, including inspection of poultry eggs for freshness and for micro cracks [5; 6]; evaluation of tenderness, color, and pH of beef [7; 8]; identification of systemically diseased chickens [9; 10]; detection of citrus canker disease [11]; detection of contaminants and pathogens in fresh produce and meat [12; 13; 14; 15]; and detection of meat adulteration [16; 17; 18]. Among the optical techniques, visible/near infrared spectroscopy, fluorescence spectroscopy, hyperspectral imaging, and Raman spectroscopy and imaging are extensively utilized for food authentication research and application [19; 20; 21; 22; 23; 24; 25]. Raman spectroscopy and imaging techniques are valuable tools for food production and quality control applications, largely due to their specificity, sensitivity, simplicity, and non-sensitivity to water, which permit use with a wide variety of food and food products. Some examples include real-time monitoring of multiple components during wine fermentation and vinegar fermentation [26; 27]; detection of adulteration of olive oils [28]; prediction of meat spoilage [29]; discrimination of meats such as beef and horsemeat [30]; and detection of adulteration of food powders such as melamine in milk, benzoyl peroxide in flour, maleic acid in starch, and metanil yellow dye in turmeric [31; 32; 33]. Although Raman spectroscopy is a proven tool for chemical analysis, its use is often limited to very small sample volumes. The inability to acquire information from large surface areas is a major drawback in the measurement of heterogeneous samples such as food powder mixtures. Raman spectral imaging is an alternative technique that combines Raman spectroscopy and imaging to acquire Raman chemical images containing pixel-based spatial and spectral information. From this data, simultaneous spectral analysis and image processing can be performed for a wide range of food samples for safety and quality purposes [25]. Given the widespread consumption of food powders, it is important to detect the ingredient composition in it. [PERSON] et al. (2013) used Raman imaging for detection of multiple chemical adulterants in skim milk powder [34]. The study has shown Raman imaging as a potential tool for the detection of multiple components in skim milk powder. In addition to detecting components, it is equally important to evaluate its concentration in food powder mixture. This study provides a method for the detection and evaluation of percentage composition of different components in food powder.