Organic acids as a freshness indicator for tofu (soybean curd)

Area of Science:

• Food Science
• Microbiology
• Analytical Chemistry

Background:

• Tofu freshness is crucial for consumer acceptance and safety.
• Traditional microbial counts are time-consuming for assessing tofu quality.
• Organic acids may serve as rapid indicators of microbial spoilage in food products.

Purpose of the Study:

• To investigate organic acids as potential freshness indicators for tofu.
• To correlate organic acid concentrations with microbial growth during tofu storage.
• To compare organic acid analysis with microbial counts for tofu quality assessment.

Main Methods:

• Analyzed organic acids (phytic, oxalic, citric, lactic, formic, acetic) and total bacterial counts in packed and unpacked tofu.
• Stored tofu at 4°C, 10°C, and 25°C for 15 days, with analysis every 3 days.
• Utilized high-performance liquid chromatography for organic acid analysis and plate counting for microbial analysis.

Main Results:

• Oxalic, citric, and formic acid levels decreased during storage.
• Lactic and acetic acid levels significantly increased at 10°C.
• Acetic, lactic, and formic acids showed significant correlations with microbial levels in packed tofu.

Conclusions:

• Acetic, lactic, and formic acids are promising indicators for predicting tofu freshness.
• Organic acid analysis provides an effective and potentially faster method for tofu quality assessment compared to microbial counts.