Vol. 14(1), pp. 1-9. May, 2024. 

ISSN: 2384-616X

https://doi.org/10.14662/arjb2026340

 

Full Length Research

 

Abstract

This study investigated the biochemical differences between intact and naturally decayed onion tissues (Allium cepa L.) using spectrophotometric assays and pH profiling. Fresh onion bulbs were purchased from local markets in Sapele, Delta State, Nigeria, and stored under ambient laboratory conditions prior to analysis. Visibly decayed onion tissues were compared with intact tissues to evaluate changes associated with natural spoilage. Hydrolytic enzyme activities (pectinase, cellulase, and protease), DNPH-reactive carbonyl compounds, absorbance at 370 nm, tissue pH, total phenolics, reducing sugars, and soluble protein content were quantified using standard biochemical methods. Decayed tissues showed significantly higher pectinase, cellulase, and protease activities, indicating extensive degradation of structural polysaccharides and proteins. Carbonyl compounds, reducing sugars, tissue alkalinity, and dark pigment index also increased markedly, while total phenolic and soluble protein contents declined substantially. These biochemical alterations suggest enhanced oxidative metabolism, cell wall degradation, and depletion of antioxidant compounds during spoilage. Statistical analysis confirmed significant differences between intact and decayed tissues (p < 0.00625 after Bonferroni correction). The findings demonstrate that integrated spectrophotometric profiling combined with pH measurement provides a rapid, low-cost, and culture-independent approach for assessing onion spoilage. Although the assays used are semi-specific and do not identify particular spoilage organisms, the biochemical patterns observed provide useful indicators of tissue deterioration and may support the development of practical post-harvest monitoring systems, especially in resource-limited settings.

 

Keywords: Onion spoilage; spectrophotometry; pH; pectinase; DNPH‑reactive carbonyls; total phenolics; reducing sugars; soluble protein; post‑harvest biochemistry

 

	Cite This Article As: Agbini, O.A., Akpobire, O (2026). Spectrophotometric and pH Profiling of Biochemical Changes in Intact and Naturally Decayed Onion Tissues (Allium cepa L.). Acad. Res. J. Biotech. 12(1): 1-9