This study aims to use of medicinal and edible ramie leaf(Boehmeria nivea L.) as a material for functional foods. The fresh ramie leaf was dried with hot-air, cold-air and freeze drying methods. They were powdered and analyzed their physicochemical compositions including proximate composition, vitamin C, amino acid, fatty acid, mineral, and color. The antioxidant activities of the powered ramie leaf were also analyzed by DPPH radical scavenging activity, ABTS radical scavenging activity, total polyphenol. In addition, quality characterization of pork patties added with varying amounts of freeze-dried ramie leaf powder were also investigated in this research.
Crude protein, crude fat, crude ash contents were highest in freeze-dried ramie leaf powder, while moisture content was highest in cold-air dried ramie leaf powder. Vitamin C content was higher in freeze-dried ramie leaf powder. The total and essential amino acid were higher in freeze-dried ramie leaf powder and the major amino acids were glutamic acid, aspartic acid, and leucine. The ratio of essential amino acid was highest in cold-air dried ramie leaf powder. The major fatty acids in ramie leaf powder were linolenic acid, linoleic acid, palmitic acid, oleic acid, palmitic acid, and stearic acid. The contents of unsaturated fatty acids was higher than that of saturated fatty acids, and unsaturated fatty acid contents were higher in freeze-dried ramie leaf powder. In mineral contents, Ca was the highest followered by K, Mg, P and Na. Brightness(L*) and yellowness(b*) of chromaticity was the highest, while redness(a*) was lowest in the freeze-dried ramie leaf powder.
The freeze-dried ramie leaf powder showed the highest DPPH radical scavenging activity, ABTS radical scavenging activity and total polyphenol content followed by hot-air dried powder and cold-air dried ramie leaf powder.
The moisture contents of pork patties containing freeze-dried ramie leaf powder were lower than that of control patty, but there was no significant difference in moisture and pH values between the patties. With increasing amounts of freeze-dried ramie leaf powder in pork patties, chromaticity decreased in brightness(L*) and redness(a*), but increased in yellowness(b*) in the raw and cooked patties. In texture analysis, hardness, springiness, cohesiveness, and chewiness of the pork patties increased as more freeze-dried ramie leaf powder was added to the pork patties. Cooking loss had a tendency to decrease in pork patties containing ramie leaf powder compared with the control group. Thiobarbituric acid reactive substances (TBARS) values increased during storage in pork patties without freeze-dried ramie leaf powder, but those formulated with freeze-dried ramie leaf powder showed lower TBARS values than those in the control groups. Sensory panels determined that pork patties containing 0.5%(w/w) freeze-dried ramie leaf powder had higher scores for overall acceptability.