engleski

Effect of high voltage electrical discharge treatment and drying technology on properties of cocoa shell

Cocoa bean shell is a by-product of a chocolate industry that is separated from cocoa beans before or after roasting. It is rich in fibres, proteins, and bioactive components and very interesting material for the enrichment of nutritionally poor food products. Since the shell is very exposed to external factors during the whole processing of the beans, it can be contaminated with different microorganisms, toxins, polycyclic aromatic hydrocarbons, acrylamide, 5-hydroxymethylfurfural, etc. High voltage electrical discharge treatment (HVED) is known to reduce some of those contaminants. HVED is conducted in water by generating electrical discharge (emission of different radicals and UV-light) between two submerged electrodes. After the treatment, drying of the treated material is needed. In this study, we examined the influence of freeze- and oven drying of HVED treated cocoa shell on water activity, water and oil binding capacity, colour, and total phenolic content. Control samples were prepared by shearing in water and freeze- and oven drying. Results showed that the water activity of control and HVED-treated samples was lower than in untreated cocoa shell. Freeze-drying and HVED had an even greater impact on the reduction of these values. Water and oil binding capacity are important for the potential use of the cocoa shell in food production. These parameters showed that HVED increased water binding and decreased oil binding compared to control samples. In addition, HVED treated samples had a greater total colour change compared to control samples. Oven drying caused a darkening of the samples, while freeze- drying had a brightening effect. Total phenolic content of cocoa shell decreased with all applied treatments, and freeze drying was less detrimental for the phenolics than oven drying.

cocoa shell ; high voltage electrical discharge ; drying technology ; phenols ; water activity

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