18D-28

M. LIN¹, M. Al-Holy¹, B. Rasco¹, A. Cavinato², D.-H. Kang³, and S.-S. Chang⁴. (1) Food Science & Human Nutrition, Washington State Univ., PO Box 646376, Pullman, WA 99164-6376, (2) Chemistry and Biochemistry Program, Eastern Oregon Univ., One University Blvd., La Grande, OR 97850-2899, (3) Dept. of Food Science & Human Nutrition, Washington State Univ., PO Box 646376, Pullman, WA 99164-6376, (4) Food Science & Human Nutrition, Washington State University, POBox 646376, Pullman, WA 99164-6376

Alicyclobacillus, a thermoacidophilic bacterium, causes spoilage in pasteurized and heat-treated apple juice products. This microorganism is an important target spoilage organism in the quality control of acidic foods because some Alicyclobacillus spores are able to germinate and grow in highly acidic environments producing guaiacol which causes medicinal or antiseptic off-flavor in apple juice. It is difficult to visibly detect the spoilage in apple juice caused by Alicyclobacillus because the spoiled juice usually looks normal with light sediments, and has no gas production or incipient swelling of packages. The aim of this study was to investigate the feasibility of using Fourier transform infrared spectroscopy (FT-IR) to discriminate between isolates of Alicyclobacillus recovered from apple juice samples. FT-IR was used to discriminate between eight Alicyclobacillus isolates in apple juice. Multivariate statistical methods [the principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA] were used to analyze the spectral data. FT-IR vibrational combination bands reflected differences in the biochemical composition of Alicyclobacillus bacterial cell membrane components in the “fingerprint region” at wavenumbers between 1500 and 800 cm-1. Distinctive segregation among spectral sample clusters of different Alicyclobacillus isolates was observed using PCA, suggesting that this method can be highly selective. Results of SIMCA analysis demonstrated that a sound classification of guaiacol producing and non-guaiacol producing Alicyclobacillus isolates can be achieved. This technique may provide a tool for fruit juice producers to detect Alicyclobacillus more rapidly and therefore to monitor and control the potential formation of guaiacol.

Session 18D, Food Microbiology: General
2:00 PM - 5:30 PM, Sunday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana