Study On Utilization Of Chinese Bayberry (Myrica Rubra Sieb.et Zucc.) Stone

Bayberry (Myrica rubra Sieb. et zucc.) is mainly cultivated in China. As the byproduct of bayberry fruit juice or wine industries, the amount of bayberry stone, which comprise 10%or more by the weight of the bayberry fruits, is quite large. But bayberry stone has not been exploited at present, because of the lack of basic information on it. At first, the composition of bayberry stone and kernel was detemined and analyzed. A comprehensive and systematic research and discuss on bayberry stone, including oil, protein, activated carbon and wood vinegar was carried out. The objective of this study was to provide basis for exploitation of bayberry stone.The main results were presented as follows:(1) Forteen Chinese bayberry stones, include'Biqi','Dongkui','Wandao','Tanmei', 'Wuzi','Ding-ao','Zaoda','Chida','Lizhi','Zaose','Chise','Fenghong','Baiyangmei', 'Shujingyangmei'were collected from deferent areas of Zhejiang province, China, and main physico-chemical characteristics were measured. The main composition of bayberry stone was crude fibre (63.71-68.72%DW). Bayberry kernel was rich in fat (58.12-68.15%DW) and protein (22.06-26.17%DW). In acute toxicity test, the medium lethal dose of bayberry kernel on ICR rats was more than 20.0 g/kg (body weight), which indicated bayberry kernel was actually no toxicity according the standard of toxicity grade classification.(2) Bayberry fatty acids mainly were oleic acid (35.61-49.58%) and linoleic acid (34.04-49.30%). Compared to cold extraction method, ultrasonic extraction method has many advantages in oil quality and stability, and need shorter extraction time and lower extraction temperature. The influencing extents of the 4 factors are:material to liquid ratio> extraction time> ultrasonic power> ultrasonic frequency, and the optimal extracting parameters were obtained as the ultrasonic frequency 60 kHz, the ultrasonic power 10 W, the extracting time 30 min, and material to liquid ratio 1:12, and as result the yield is 59.22%. Antioxidant can improve the oxidative stability of bayberry kernel oil obviously, and TBHQ has the best effect.(3) Bayberry kernel protein possessed 18 amnio acids, and was rich in glutamic, arginine, aspartic and methionine acids while limited in lysine. The optimal alkaline extracting process of bayberry kernel protein was:pH10,50℃,45 min, and material to liquid ratio 1:15, and the extraction rate is 88.2%. The isoelectric point of bayberry kernel protein was 3.5. The protein content of bayberry kernel protein isolate prepared by alkali extraction and acid precipitation reached 91%. Under different conditions (protein concentration, pH, temperature, salt and sugar consentration), bayberry kernel protein isolate showed different functional properties (solubility, water hold capacity, oil hold capacity, foamability, emulsifying property and gelation), which provides theoretical basis for the application ranges of protein isolate in different food systems.(4) The iodine and methylene blue adsorption abilities of steam-activated carbon from bayberry stone reached 1219 and 162 mg/g, respectively. The optimal process of bayberry stone steam-activated carbon is:900-950℃,1.5-2 h and steam comsumption of 250-300 ml/50g bayberry stone carbon. Activation temperature had significant effect (P<0.05) on the yield and adsorption abilities of bayberry stone activated carbon. Activation time only had significant effect (P<0.05) on the yield, and steam consumption didn't have significant effect on yield nor adsorption abilities. Bayberry stone carbon could adsorb some toxic gas such as formaldehyde, benzene, chloroform and ammonia, and adsorption effect is: formaldehyde> chloroform> benzene> ammonia.(5) The compositions of wood vigenar from bayberry stone were mainly water, and then orgnic acids, phenol compound, ketones, aldehydes, esters, alcohols, pyridines, furans, alkanes and so on. Bayberry stone wood vigenar and its ethyl acetate extract showed good antioxidative capacity in antioxidant systems such as FRAP, DPPH and ABTS in vitro. The antioxidative capacity of bayberry stone wood vinegar was linear positive correlation with their total phenolic content (R₂=0.8636-0.9896), suggesting that phenol compound may be the key antioxiditive compositions. Bayberry had antibacterial effect on gram-positive bacteria (Staphyloccocus aureus, Bacillus subtilis and bacillus cereus) and gram-negative bacteria (Escherichia coli, Salmonella Lignieres and Pseudomonas putida), which is mainly due to its components except acidic components.