Increased shelf life of a bioherbicide through combining modified atmosphere packaging and low temperatures

Abstract

The effects of air temperatures (4, 14 and 24°C) and modified atmosphere packaging (MAP) (0% CO₂/100% N₂; 20% CO₂/80% N₂ or 40% CO₂/60% N₂) on vigour of a Sclerotinia minor barley formulation during 6 months storage were evaluated. The study was performed using a multilevel factorial experimental design and response surface methodology (RSM) and aimed to determine the optimum combination of the above factors that resulted in retention of S. minor vigour during storage. Temperature and storage duration are the main factors that affect S. minor vigour. CO₂ concentration had no effect on S. minor vigour during storage. However, oxygen displacement from storage containers by CO₂ and N₂ resulted in significant decrease of vigour reduction of S. minor as compared to ambient air control. An acceptable level of S. minor vigour reduction (ALVR) during storage was developed and determined to be ALVR=31.7±14.8% (mean±95% CI). Contour plot analysis indicated that the S. minor barley formulation at 0.4 water activity could be stored for 6, 12 or 26 weeks without exceeding the upper ALVR threshold (ca. 46%) at air temperatures not higher than 20, 17 or 11°C, respectively.

Keywords:

• Sclerotinia minor
• barley formulation
• storage
• modified atmosphere packaging (MAP)
• storage temperature
• acceptable level of vigour reduction (ALVR)

Acknowledgments

Authors grateful for the financial support from the Natural Sciences and Engineering Research Council of Canada Discovery and I to I programs and the valuable contributions from colleagues: Simona Teshler and Boris Touvykine (McGill University, Canada) for S. minor vigour testing and data preparation for statistical analysis; Professor E. Mencher (Tiraspol University, Moldova) and Dr V. Catana (Oklahoma State University, USA) for useful suggestions on RSM applications; Bernard Cayouette for help with MAP set up, gas composition and water activity monitoring throughout the experiment; Allison Pollock for reviewing the manuscript and Professor J. P. Smith (Food Science Department, McGill University) for sharing his extensive knowledge of various methods used in food technology; the two anonymous reviewers for their valuable suggestions to improve the manuscript.