Abstract
Hyperspectral imaging (1000–2500 nm) was used for rapid prediction of moisture and total lipid content in intact green coffee beans on a single bean basis. Arabica and Robusta samples from several growing locations were scanned using a “push-broom” system. Hypercubes were segmented to select single beans, and average spectra were measured for each bean. Partial Least Squares regression was used to build quantitative prediction models on single beans (n = 320–350). The models exhibited good performance and acceptable prediction errors of ∼0.28% for moisture and ∼0.89% for lipids.This study represents the first time that HSI-based quantitative prediction models have been developed for coffee, and specifically green coffee beans. In addition, this is the first attempt to build such models using single intact coffee beans. The composition variability between beans was studied, and fat and moisture distribution were visualized within individual coffee beans. This rapid, non-destructive approach could have important applications for research laboratories, breeding programmes, and for rapid screening for industry.
Highlights
Coffee is one of the most popular beverages worldwide, and the quality of the final product is defined by several factors. Most of these strictly depend on the green bean composition (Illy and Viani, 2005), including moisture and fat, which are among the main constituents of green coffee beans
But even better performance (Rc2v 1⁄4 0.858 and RMSECV 1⁄4 0.276%) despite employing a Hyperspectral imaging (HSI) approach on intact coffee beans, as opposed to using a NIR instrument on ground coffee material as in Morgano et al (2008)
We demonstrated the wide distribution of lipid content within the same batch and between batches, and developed a moisture calibration that is capable of detecting problematic seeds within the population
Summary
Coffee is one of the most popular beverages worldwide, and the quality of the final product is defined by several factors Most of these strictly depend on the green bean composition (Illy and Viani, 2005), including moisture and fat, which are among the main constituents of green coffee beans. Rancidity as a food defect comprises oxidative or hydrolytic rancidity, and is strongly influenced by the fatty acid composition and the total amount of fat present. Diterpenes, both free and esterified, form 0.2e1.2% of coffee constituents. There is a layer of wax on their surface, accounting for 0.2e0.3% of the coffee weight (Farah, 2012)
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