Starter Culture‐Induced Fermentation Reveals Genotype‐Driven Variability in the Composition and Quality of Brazilian Amazon Forastero Cocoa Beans

TL;DR

This study shows that the genetic makeup of cocoa beans strongly affects their quality and chemical composition during fermentation, even when using starter cultures.

Contribution

The study reveals genotype-driven variability in cocoa bean fermentation outcomes using controlled starter cultures.

Findings

Genetic background strongly determines chemical composition and quality of fermented cocoa beans.

Nine genotypes showed significant decreases in polyphenol content after fermentation.

Principal component analysis grouped genotypes by chemical traits, highlighting differences in acidity, sugar levels, and fermentation completeness.

Abstract

Cocoa (Theobroma cacao L.) is a crop of major economic importance, with Brazil ranking sixth in global production and Pará leading national output. Bean quality is strongly influenced by genetic diversity and postharvest processing, particularly fermentation. To minimize batch heterogeneity, this study evaluated 18 Forastero genotypes from the Brazilian Amazon under induced fermentation with selected starter cultures. Pods were collected from the CEPLAC germplasm bank (Medicilândia, Pará). Small‐scale fermentations (800 g, 144 h) were conducted using Pichia kudriavzevii, Lactiplantibacillus plantarum, and Acetobacter pasteurianus, followed by sun drying. Beans were analyzed for physical traits, cut test, pH, fermentation index (FI), total polyphenols (Folin–Ciocalteu), sugars, and organic acids (UHPLC). After fermentation, the average pH reached 4.97, and the moisture decreased below 8 g/100 g, ensuring stability. The FI increased from 0.62 to 1.02, indicating adequate fermentation except for CAB324, MA11, MA15, and IMC67. Polyphenols decreased significantly in nine genotypes, ranging from 11.32 to 24.59 g GAE/100 g DM. Sucrose was almost completely hydrolyzed, resulting in higher fructose and variable glucose levels. Bean sizes varied from standard to very small. Principal component analysis grouped genotypes by chemical traits: CCN51 (larger beans, high fructose/glucose), PA195/PA121 (greater acidity), and IMC67 (pH 5.85, residual sucrose, violet cotyledons) showed incomplete fermentation. The results demonstrate that, even under controlled starter‐culture fermentation, genetic background strongly determines the chemical composition and quality of Brazilian Amazon cocoa beans.

This study provides insights for cocoa producers and chocolate manufacturers to optimize fermentation according to genotype‐specific responses. By using starter cultures and understanding genetic influences on bean chemistry, producers can achieve more consistent quality, supporting the development of traceable and high‐value Amazonian cocoa products.

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