Aims: To develop a mild blanching method with calcium salts to ensure microbiological safety and quality of fresh-cut spinach. Methods and Results: The antimicrobial efficacy of eight calcium salts was evaluated on Escherichia coli O157:H7 at 45-65°C and calcium hydroxide (Ca(OH)<inf>2</inf>) showed the greatest synergistic antimicrobial effect with heat. Combinations of low temperature treatments (45, 55, 65°C), time (20, 40, 60 s) and Ca(OH)<inf>2</inf> (0·25, 0·50, 0·75%) were applied for E. coli O157:H7 disinfection on fresh-cut spinach to develop a predictive model using a Box-Behnken experimental design. A suitable quadratic model was produced (R<sup>2</sup> = 0·98, P < 0·001) and the optimum condition (64·9°C with 0·52% Ca(OH)<inf>2</inf> for 42·4 s) was drawn by reducing 6·6 log CFU g<sup>-1</sup> of E. coli O157:H7 on fresh-cut spinach. Blanching at 61·9°C with 0·52% Ca(OH)<inf>2</inf> for 41·7 s can inactivate E. coli O157:H7 on spinach by 5·4 log CFU g<sup>-1</sup>. The new method was comparable to the CDC recommendation for safe spinach cooking (71·1°C, 15 s; 5·0 log CFU g<sup>-1</sup> reduction) with lower levels of weight loss of the spinach (P < 0·05). Conclusions: This study suggests an efficient spinach blanching method for E. coli O157:H7 disinfection. Significance and Impact of the Study: This blanching method will enhance microbiological safety of fresh-cut produce while minimizing the use of energy and chemicals.
- EHEC (enterohaemorrhagic E. coli)
- Food safety
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology