Food Structure


Permanganate, dioxane, ozone, and hydrogen peroxide, which delignify plant materials, were evaluated for their disruptive action on plant structure, the ir modification of histological reactions for Iignins, and their change in in vitro digestibility by rumen microorganisms of yollng-Tsecond internode from top) and old (fourth and fifth internodes) bermudagrass stems. Epidermis, sclerenchymaring, and vascular tissue (except phloem) gave positive reactions with acid phloroglucinol (AP) or chlorinesulfite (CS) in all samples , whereas cortex and parenchyma in older stems gave a positive reaction with CS. Treatment with delignifying agents reduced the reactions for lignin, with permanganate- treated tissues having the least reaction. Gravimetric data indicated that KMn04 removed about 25% of the dry matter, with the other treatments resulting in no loss with ozone to 34% with hydrogen peroxide. Scanning electron microscopy (SEM ) indicated that delignifying agents distorted parenchyma tissues, often resulting in collapsed cell walls . Permanganate especially disrupted parenchyma and the more rigid vascular bundle tissue and caused the most destruction of all the treatments. Ozone was effective in partially breaking downlignified vascular tissue in one sample set but not in a second , more mature set. Delignification resulted in improved in vitro dry matter digestibility by rumen microorganisms for the resultant fiber compared with neutral detergent fiber for all treatments, with permanganate causing the largest increase for both sample sets. SEM showed that chemical treatments improved degradation of the cortex and parenchyma, whereas the epidermis, sclerenchymaring, and vascular tissue (except phloem) still resisted microbial breakdown.

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