ABSTRACT
With the unprecedented development of the food
industry, food preservatives have gained a leading role in food processing. In
this study, investigations were carried out to assess the cytological effects
of potassium metabisulphite (PMB) to onion (Allium cepa), one of the
most used plants for determining the cytotoxic and genotoxic effects of
different chemicals. Meristematic roots of A. cepa were treated with PMB
solutions in different concentrations, ranging from 10 mg/l to 35 mg/l for 6,
12 and 24 h alongside an untreated control. The quantified parameters for the
different concentrations of the PMB were mitotic index (MI %), mitosis phases
index (PI %) and total abnormalities index (TAI %) meaning chromosomal
aberrations and nuclear abnormalities. The results indicated that PMB reduced
MI in A. cepa with increasing the concentrations and time exposure as
compared with the untreated control. Thus, at concentration of 10 - 35 mg/l
PMB, these values were reduced from 8.34% to 4.81% (6 h); 7.18% to 2.35% (12 h)
and 4.12 to 1.43 (24 h). Also, the TAI value increased with increasing PMB
concentrations and time: 0.51% to 9.98% (6 h), 7.11% to 19.84% (12 h) and 17.79
to 41.21 (24 h). The types of abnormalities induced by PMB in A. cepa meristematic cells were micronucleus, C-metaphase, star anaphase, stickiness,
laggards, fragments, binucleated cells and pulverised nucleus. These alarming
findings indicate the cytotoxic and genotoxic effect of PMB to A. cepa and suggest necessity to adopt more natural alternatives for food preservation
in the future.