Stability of sorbic acid in intermediate moisture systems

Area of Science:

• Food Science
• Food Chemistry
• Microbiology

Background:

• Intermediate foods have reduced water activity (aw ≈ 0.85) to inhibit bacterial growth.
• Moulds and yeasts can still grow at these water activities, necessitating antimycotics like sorbate.
• Sorbate is prone to oxidation, potentially leading to undesirable reactions in foods.

Purpose of the Study:

• To investigate the oxidation of sorbate in model systems and intermediate moisture meat products.
• To identify the reaction products of sorbate oxidation and their impact on food components.
• To assess the effect of sorbate on protein quality in intermediate moisture meat products.

Main Methods:

• Model systems and intermediate moisture meat products were prepared with sorbate.
• Water activity was adjusted to 0.85.
• Samples were stored at 38°C or 65°C.
• Oxidation products, pH, and thiobarbituric acid-reactive substances were measured.
• Protein covalent linkages and sorbate concentration were analyzed.

Main Results:

• Sorbate oxidation products reacted with lysine, glutamate, and haemoglobin in model systems.
• Oxidation increased pH and formed thiobarbituric acid-reactive substances.
• In meat products, sorbate induced protein covalent linkages at 38°C.
• Sorbate concentration decreased by half over 4 months at 38°C.

Conclusions:

• Sorbate oxidation can lead to non-enzymic browning reactions and protein modification in intermediate foods.
• These reactions negatively impact the quality of intermediate moisture meat products.
• Further research is needed to understand the full implications for food quality and safety.