88E-24 |
Alteration of texture and yield of processed mushrooms (Agaricus bisporus) |
S. ZIVANOVIC and R. W. Buescher. Department of Food Science, University of Arkansas, 2650 North Young Avenue, Fayetteville, AR 72704 During retorting fruits and vegetables soften while mushrooms undergo different textural changes. Moreover, shrinkage of thermally processed mushrooms can reach 40% and is speculated to be related to amount of proteins, dry matter and calcium. Identification of responsible factors and mechanisms involved in structural changes that occur during processing will assist with designing improvements. Our objectives were to 1) characterize textural changes that occur during retorting of mushrooms, 2) alter texture and yield of processed mushrooms by of oxidation, reduction, and cross-linking agents, and to 3) determine the effect of those alterations on proteins, carbohydrates and chitin. Mushrooms were blanched and processed at 121°C for 25min. Fill ratio was 60% mushrooms and 40% brine. The cover brines were prepared to achieve equilibrated concentration of 1% salt, and chosen levels of azodicarbonamide, cysteine, or CaCl2. Samples were evaluated after 7 days and 3 months storage at the room temperature. Texture was determined as force for puncturing of single cap and as peak force for shearing 100g mushrooms. Yield was recorded as drained weight. Proteins, carbohydrates, and chitin were analyzed in alcohol insoluble solids and in sequential extracts. Thermal processing increased force for puncturing (4.36N vs. 2.33N for fresh) but reduced shear press readings (96kg vs. 159kg for fresh). In processed mushrooms, texture was affected only by calcium: shear force was 112kg with 25mM CaCl2 vs. 97kg for control, while force for puncturing was 4.96N, 4.91N, and 4.36N for 25mM, 5mM CaCl2, and control, respectfully. Treatments with cysteine enhanced yield by 5% but did not affect texture. Cysteine enhanced solubilization of polysaccharides and chitin, while calcium caused cross-linking between proteins and polysaccharides that reduced structural degradation. The results indicated that texture and yield of processed mushrooms could be altered by the calcium and reducing agent, respectfully.
Session 88E, Fruit & Vegetable Products: Processing
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