Date of Award

8-2009

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Alfred Bushway

Second Committee Member

Beth Calder

Third Committee Member

Renae Moran

Abstract

FDA recently set limits on concentration of patulin in apple cider at 50 parts per billion (ppb). One method to reduce patulin in cider involves reducing patulin-producing molds on apples destined for cider pressing. Fumigations with peracetic acid (PAA) and with vinegars have shown to cure infestations of various molds. Treatment with Pseudomonad biocontrol agents (BCA) has shown to protect against further infestation by molds. However, fumigation is prohibitively expensive for many cider producers, and there is not yet a sufficient process that both cures and protects against mold infestation. The efficacy of white distilled vinegar fumigation in curing an infestation of Penicillium expansum on apples using a home humidifier was assessed. Other treatments evaluated were vinegar pretreatment in combination with BCA and vinegar fumigation versus PAA fumigation. Apples were treated with or without BCA, inoculated by dipping in a suspension containing 103 P. expansum spores mL-1, placed inside a sealed room, and vinegar or PAA was vaporized using a humidifier. Next, apples were treated with or without BCA, inoculated again or not, wounded with a sterile glass rod, and stored in plastic tubs, at room temperature, under a laminar flow hood for 2-3 weeks. After incubation, apples were visually inspected for mold infestation; wounds were sampled, and viable mold spores enumerated, using 3M™ Quick Swabs and 3M™ YM Petrifilms. Vinegar fumigation was effective at reducing endemic molds to below detectable levels on 89% of apples and reducing the 3 Log10 P. expansum inoculation to undetectable levels on 89% of apples. Vinegar fumigation was found to significantly improve the efficacy of BCA at protecting against infestation of P. expansum (p<0.001). Vinegar fumigation was found to be significantly more effective than PAA fumigation (pO.OOl). This research provides another measure for cider producers developing HACCP plans that address the reduction of patulin in their cider.

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