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BULK HANDLING, STORAGE & LOGISTICS
Analysing apple chip production using
NIR spectroscopy
D
ried snack foods such as NIR works by scanning the prodapple chips are becoming uct with invisible light, Kamruzzaincreasingly popular as man explains. a convenient alternative “With our eyes we can see the to fresh fruit. In order to meet the size, shape and colour of food, demand for variety, food manufacbut we cannot see the nutritional turers are coating such snack foods composition. The near-infrared with fruit and vegetable powders to light reads the chemical bonds in enhance taste and sensory appeal. the food, so you can analyse any A new study from the University biological matter and determine of Illinois explores the drying process features such as moisture content, of coated and uncoated apple chips protein, fat, fibre, or carbohydrates. University of Illinois graduate students Ragya using near-infrared (NIR) spectrosThe NIR spectroscopy will give Kapoor, Food Science and Human Nutrition, and Amir Malvandi, Agricultural and Biologicopy to measure moisture content you many data points; we extract cal Engineering. in real time. the data and use machine learning Image credit: College of ACES, University of Illinois. The purpose of coating is to make to interpret the results,” he states. dried apple chips more functional “The combination of NIR specand nutritional, as well as more appealing to eat, explains troscopy and machine learning is very powerful.” Ragya Kapoor, graduate student in Food Science and Human Kapoor, Kamruzzaman, and study co-authors Amir Malvandi, Nutrition (FSHN) at U of I and lead author on the paper. graduate student in ABE, and Hao Feng, professor of food and “The idea is to get school-aged children to include apple chips bioprocess engineering at U of I, had two main research goals. in their diet. We use a cranberry powder coating to make the They wanted to explore edible coating on apple slices and test apple slices more attractive in terms of colour and taste,” Kapoor the use of NIR spectroscopy to monitor the drying process for said. “We dip the apple slices in a liquid-based solution for coated versus uncoated slices. 60 seconds twice, and then conduct the hot air-drying operation.” “The moisture content is different for coated and uncoated The researchers check the moisture content at various points samples, and we wanted to see how drying behaviour differs throughout the drying process with miniature NIR spectroscopy for them. We found that with NIR technology we are able to to ensure the chips are dry enough. differentiate between the two samples based solely on the difNIR technology offers advantages compared to standard ference in their composition,” Kapoor explains. monitoring techniques, said Mohammed Kamruzzaman, assisThe results showed that the miniature NIR spectroscopy was tant professor in the Department of Agricultural and Biological able to monitor the drying process and discriminate between the Engineering (ABE) at U of I and co-author on the paper. coated and uncoated apple slices and drying times, primarily by “In traditional methods, you take samples from the production the differences in sugar and water absorption bands. for lab analysis. The process takes at least 24 hours, the samples As the NIR allows the user to see the product’s changing are destroyed, and some analyses require harsh chemicals,” moisture content in real time, the researchers said the process Kamruzzaman said. can be used to enhance production efficiency. In contrast, NIR spectroscopy takes a few seconds, does “You can continuously monitor the drying process, observe not require the removal of samples, and uses no chemicals. the amount of dry matter, and decide the right time to stop,” “Traditional lab techniques need experts to handle the equip- Kamruzzaman said. ment and interpret the data. NIR is easy to use, and almost The paper, “Real-time moisture monitoring of edible coated anyone can handle the instrument and take the measurement apple chips during hot air drying using miniature NIR spectroswith just a few minutes of training. And the equipment is copy and chemometrics”, is published in LWT – Food Science and Technology. small and portable.” 58
January/February 2022
www.foodprocessing.com.au
