In order to develop a method for producing fuel ethanol from cassava pulp using cell surface engineering (arming) technology, an arming yeast co-displaying α-amylase (α-AM), glucoamylase, endoglucanase, cellobiohydrase, and β-glucosidase on the surface of the yeast cells was constructed. The novel yeast strain, possessing the activities of all enzymes, was able to produce ethanol directly from soluble starch, barley β-glucan, and acid-treated Avicel. Cassava is a major crop in Southeast Asia and used mainly for starch production. In the starch manufacturing process, large amounts of solid wastes, called cassava pulp, are produced. The major components of cassava pulp are starch (approximately 60%) and cellulose fiber (approximately 30%). We attempted simultaneous saccharification and ethanol fermentation of cassava pulp with this arming yeast. During fermentation, ethanol concentration increased as the starch and cellulose fiber substrates contained in the cassava pulp decreased. The results clearly showed that the arming yeast was able to produce ethanol directly from cassava pulp without addition of any hydrolytic enzymes.

Natural rubber (NR) is sensitive to oxidative degradation, which needs to add commercial antioxidant for NR compounding to improve its aging properties.The aim of this study is to apply natural antioxidant obtained from extracted rambutan peel powder (RE) by methanol compared to commercial antioxidants for NR compounding in a conventional vulcanization (CV system). Two types of commercial antioxidants were N-(1,3-dimethylbutyl)-N'phenyl-pphenylenediamine (6PPD) and 2,2,4-Trimethyl-1,2dihydroquinoline (TMQ).The main phenolic compounds in RE were geraniin, corilagin, ellagic acid and gallic acid which had greater antioxidant activity based on all methods, especially for 2,2-Diphenyl-2-picrlhydrazyl radical-scavenging assay (DPPH) and had a similar antioxidant activity to 6PPD. The antioxidants were applied in NR vulcanizates at 1 phr and 2 phr to study their physical and mechanical properties. The decomposition temperature of RE was higher than for 6PPD but similar to TMQ. The decomposition temperature of the rubber vulcanizates containing RE was higher than for the commercial antioxidants. Rubber vulcanizates with RE retained similar tensile strength and modulus at 100% strain as the commercial antioxidants. Furthermore, the addition of RE in rubber vulcanizates helped to resist thermal aging at 70 C and ozone aging, particularly at 1 phr at least as well as in the commercial antioxidants. Therefore, RE can be used as an alternative natural antioxidant in natural rubber to replace commercial antioxidants.

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This study extracted ellagitannins from rambutan peel using the Soxhlet technique. The extract was further partitioned and fractionated to get extract rich in ellagitannin and geraniin, respectively. The partitioning of the extract significantly increased total phenolic content (TPC) by 36.3% and its biological properties. Mineral elements such as Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn were identified in both peel and extract. Ellagitannins such as geraniin and corilagin with metabolites (gallic acid and ellagic acid) were identified as the major compounds. Analysis of antioxidant activities shows that the ellagitannin rich extract is as powerful as vitamin C. Geraniin was the main contributor to the free radical scavenging activity. The study also revealed that extract with a fraction rich in geraniin has antioxidant activity equivalent to commercial geraniin (1.56 ± 0.11 Trolox equivalent g/g). It also showed low cytotoxicity on fibroblast L929 cells, moderate tyrosinase activity, and good efficacy against Staphylococcus aureus , Staphylococcus epidermidis , and Cutibacterium acnes strains. Successive fractionation of the extract is a promising technique to produce geraniin rich fractions with enhanced antioxidant property. Rambutan peel, as a natural product, is a good source of mineral elements and biologically active compounds for pharmaceutical, nutraceutical, and cosmetic formulations.