Non-invasive discrimination of roasted and unroasted cocoa bean shell of cocoa clones in Ghana and quantification of nutritional and bioactive components: a chemometric approach

Abstract

Cocoa bean shell (CBS) remains a commonly produced by-product of cocoa bean processing. It is usually obtained from fermented and dried cocoa beans that are roasted. The study investigated the potential use of Near-infrared spectroscopy (NIRS) analysis for discriminating roasted and unroasted CBS among cocoa clones and quantifying some nutritional and bioactive components in Ghana. Five clones, comprising four important seed gardens clones used across West Africa and one criollo were evaluated. Cocoa beans from the different clones (T60/887, VENC 4, MO 20, PA 150 and T60/887 × POUND 7) were divided into two parts, with one part roasted at a temperature of 120 °C for 50 min while the other part was kept unroasted. The CBSs were milled and passed through a 425 μm pore-sized sieve to obtain the powder. A handheld portable NIRS was used to scan the CBS powder in Ziplock bags. The nutritional and bioactive characterisation was carried out using official methods. NIRS discriminated the various clones of roasted and unroasted CBS. Carbohydrate was the predominant macronutrient, and ash content ranged from 5.25 to 8.24%. The CBS was high in potassium (2382–3144 mg/100 g) and low in sodium (25.67–51.33 mg/100 g). Total flavonoids and phenolics ranged from 8.61 to 40.71 mgQE/g and 6.34–12.25 mgGAE/g, respectively, for the roasted and unroasted CBS. To ensure better differentiation of cocoa beans from different clones using NIRS, incorporating roasting as a processing parameter is recommended.