# Comparison of Physicochemical Properties, Antioxidants, and Aroma Profiles of Water- and Sodium-Hydroxide-Treated Natural Cocoa Powder

## TL;DR

This study compares water and sodium hydroxide in cocoa powder alkalization, finding that water offers a greener alternative with similar color results and better antioxidant properties.

## Contribution

The study introduces water as a sustainable alternative to sodium hydroxide in cocoa alkalization, demonstrating its effectiveness in maintaining quality while improving antioxidant content.

## Key findings

- Water-treated cocoa powder showed higher antioxidant capacity compared to sodium hydroxide-treated samples.
- Water treatment preserved higher total phenolic content and improved aroma profiles with higher TrMP/TMP ratios.
- Both water and sodium hydroxide treatments achieved similar color attributes when optimized.

## Abstract

Cocoa powder alkalization is an essential process in
chocolate
manufacturing, and traditionally, this process involves the use of
alkaline agents, such as sodium hydroxide (NaOH), potassium hydroxide
(KOH), and potassium carbonate (K2CO3). However,
these methods involve harsh chemicals and energy-intensive procedures,
raising significant environmental concerns. Water (H2O)
has emerged as a promising alternative due to its safety, minimally
harmful byproducts, and accessibility. Green chemistry principles
have gained importance across industries, especially in food production,
where sustainable practices are highly valued. This study aimed to
develop a greener process by investigating the alkalization potential
of H2O and comparing the results with those of NaOH. The
particle size distribution, pH, color, antioxidant capacity, phenolic
composition, and aroma profile of cocoa powders treated with H2O and NaOH were evaluated. The alkalization temperature significantly
affected the color of the cocoa powders, and the alkali solution ratio
influenced the L* values of H2O-treated
powders. In industrial and commercial specifications, an ΔE value below 3 is considered standard for color measurements.
Both H2O-treated and NaOH-treated natural cocoa powders
had ΔE values exceeding 3 compared to the untreated
powder, indicating that H2O treatment darkens the color
in a similar way to that of traditional methods. While NaOH produced
a darker color, process optimization allowed both H2O and
NaOH treatments to achieve similar color attributes (ΔE < 3). Significant differences were observed in the
antioxidant capacity and total phenolic content (TPC) between the
H2O-treated and NaOH-treated cocoa powders. H2O treatment positively impacted the antioxidative properties of the
cocoa powder. The antioxidant capacity, measured by the DPPH and CUPRAC
methods, was significantly higher in H2O-treated samples
(295.5–317.7 TEAC mg/100 g and 835–1542 TEAC mg/100
g, respectively) compared to NaOH-treated samples (256.6–306.2
TEAC mg/100 g and 171–849 TEAC mg/100 g, respectively). Additionally,
the TPC of H2O-treated cocoa powder [281.3–321.6
gallic acid equivalent (GAE) mg/100 g] was significantly higher than
that of NaOH-treated powder (100.0–298.6 GAE mg/100 g). The
significant differences in the phenolic profiles suggested that the
alkalization process affects individual phenolic compounds differently.
Moreover, H2O-treated cocoa powders had significantly higher
trimethylpyrazine/tetramethylpyrazine (TrMP/TMP) ratios than those
of NaOH-treated samples, indicating notable differences in aroma profiles.
This study suggests that H2O can replace NaOH in the alkalization
process of the cocoa industry, particularly for lightly treated alkalized
cocoa powders that maintain high antioxidant activity and TrMP/TMP
ratios. This offers a more environmentally friendly, easily manageable,
and sustainable process for cocoa powder alkalization.