title: Optimization of low-temperature blanching combined with calcium treatment to inactivate Escherichia coli O157:H7 on fresh-cut spinach.
abstract: OBJECTIVE
  To develop a mild blanching method with calcium salts to ensure microbiological safety and quality of fresh-cut spinach.
  
  
  RESULTS
  The antimicrobial efficacy of eight calcium salts was evaluated on Escherichia coli O157:H7 at 45-65°C and calcium hydroxide (Ca(OH)2 ) 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)2 (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(2) = 0·98, P < 0·001) and the optimum condition (64·9°C with 0·52% Ca(OH)2 for 42·4 s) was drawn by reducing 6·6 log CFU g(-1) of E. coli O157:H7 on fresh-cut spinach. Blanching at 61·9°C with 0·52% Ca(OH)2 for 41·7 s can inactivate E. coli O157:H7 on spinach by 5·4 log CFU g(-1) . The new method was comparable to the CDC recommendation for safe spinach cooking (71·1°C, 15 s; 5·0 log CFU g(-1) 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.
  
  
  CONCLUSIONS
  This blanching method will enhance microbiological safety of fresh-cut produce while minimizing the use of energy and chemicals.
authors: Department of Food Bioscience and Technology, Korea University, Seoul, Korea.
authors: N H
authors: NH
authors: Kim
authors: Department of Food Bioscience and Technology, Korea University, Seoul, Korea.
authors: N Y
authors: NY
authors: Lee
authors: Food Microbiology Division, National Institute of Food and Drug Safety Evaluation, Osong, North Chungcheong Province, Korea.
authors: S H
authors: SH
authors: Kim
authors: Food Microbiology Division, National Institute of Food and Drug Safety Evaluation, Osong, North Chungcheong Province, Korea.
authors: H J
authors: HJ
authors: Lee
authors: BK 21 Plus Graduate Program, Department of Animal Science and Institute of Rare Earth for Biological Application, Chonbuk National University, Jeonju, Korea.
authors: Y
authors: Y
authors: Kim
authors: Department of Food Bioscience and Technology, Korea University, Seoul, Korea.
authors: J H
authors: JH
authors: Ryu
authors: Department of Food Bioscience and Technology, Korea University, Seoul, Korea.
authors: M S
authors: MS
authors: Rhee
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D003080:Cold Temperature; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005519:Food Preservation / Q000295:instrumentation / Q000379:methods*; D018724:Spinacia oleracea / Q000382:microbiology*
chemical_list: D002118:Calcium
keywords: EHEC (enterohaemorrhagic E. coli); antimicrobials; food safety; infection; postharvest