Bio-detheobromination of cocoa pod husks: reduction of ochratoxin A content without change in nutrient profile

Abstract

BackgroundUtilization of cocoa pod husks (CPH) in animal feed is hindered by the presence of theobromine, which is variably toxic to animals. Treatment of this agro-waste to remove theobromine, while preserving its nutrient content, would allow beneficial use of the millions of metric tonnes discarded annually. The aim of this study was to assess the suitability of selected theobromine-degrading filamentous fungi for use as bio-tools in degradation of theobromine in CPH.ResultsThe candidate fungi assessed in this study were an Aspergillus niger (AnTD) and three Talaromyces spp. (TmTD-1, TmTD-2, TvTD) isolates. All the fungi eliminated CPH theobromine, 0.15% w/w starting concentration, within 7 days of start of treatment, and were capable of degrading caffeine and theophylline. The fungi decreased CPH ochratoxin A content by 31–74%. Pectin was not detectable in fungus-treated CPH whereas parameters assessed for proximate composition were not affected.ConclusionsThe data provide ample evidence that the four isolates can be applied to CPH for the purpose of eliminating theobromine and decreasing ochratoxin A content without affecting nutrient profile. Comparatively, Talaromyces verruculosus TvTD was considered as most suitable for use as a bio-tool in detheobromination of CPH for animal feed.

Nutritional enhancement of cocoa pod husk meal through fermentation using Rhizopus stolonifer

“…There was a 46.97 to 77.2% decline in theobromine content of the cocoa pod husk meal postfermentation which is indicative of the ability of R. stolonifer to degrade the methylzanthine backbone of theobromine in the substrate. This reduction coefficient in theobromine agrees with the reports of Adamafio et al, (2011), Bentil et al, (2015), Amorim et al, (2017) and Oduro-Mensah et al, (2018) who recorded significant decline in theobromine concentration after microbial fermentation. A significant reduction in coefficient by 72% was reported for theobromine by Oduro-Mensah et al (2018) after employing a solid state fermentation of cocoa pod husk for 7 days using two strains of fungi, namely: Aspergillus niger and Talaromyces species which is still lower than 77% reported in this current study for the same fermentation period.…”

“…This reduction coefficient in theobromine agrees with the reports of Adamafio et al, (2011), Bentil et al, (2015), Amorim et al, (2017) and Oduro-Mensah et al, (2018) who recorded significant decline in theobromine concentration after microbial fermentation. A significant reduction in coefficient by 72% was reported for theobromine by Oduro-Mensah et al (2018) after employing a solid state fermentation of cocoa pod husk for 7 days using two strains of fungi, namely: Aspergillus niger and Talaromyces species which is still lower than 77% reported in this current study for the same fermentation period. The degradation of theobromine by R. stolonifer could have been made possible by using theobromine as a sole carbon and energy source via the demethylase oxidase, xanthine dehydrogenase, xanthine oxidase, urease and uricase pathway (Yamaoka-Yano and Mazzafera, 1999;Dash and Gummade, 2006;Huq, 2006).…”

“…The advent of biotechnological innovations, mainly in the area of enzyme and fermentation technology might offer potential economic utilization of cocoa pod husk. The application of effective bio-treatment approaches such as fungal biotechnology is worth considering for the improvement of the nutritional value of CPH as higher fungi have the ability to bio-transform fibrous agroresidues into value-added products through their extracellular enzyme activities (Oduro-Mensah et al, 2018).…”

Cocoa Bean Shell—A By-Product with Nutritional Properties and Biofunctional Potential

“…Among these strategies, physicochemical treatments have been proposed, such as the boiling of CBS [143,144] or hydrotropic extraction [144]. Also, several studies have proposed fungi fermentation treatments of CBS for bio-detheobromination, showing that species such as A. niger, Talaromyces, or P. ostreatus spawn are capable of metabolizing theobromine, obtaining up to a 78.13% theobromine content reduction in CBS [69,130,145,146].…”

“…Aroyeun and Adegoke [216] found an OTA reduction efficiency of 64.3%-95% by employing essential oils, while Manda et al [217] observed an average OTA decrease of 23.8% with just a controlled roasting process at 140 • C for 30 min. Oduro-Mensah et al [146] proposed a method employing filamentous fungi that degraded 31%-74% of the OTA contained in cocoa pods. Besides, CBS have been affirmed to be especially susceptible to fungi spoilage, due to the pulp residues that can remain on it after bean separation from the pods and fermentation, thus the occurrence of mycotoxins could also be partially prevented if special attention is directed to bean cleanliness after fermentation [218].…”