Study On The Analysis Of Nutrition Composition In Watermelon Seeds

The seed of watermelon which is made of shell and nutlet can be eaten or medicinal. It is the popular snack food and the representative of daily snacks. Watermelon seeds are rich in protein, fatty acid, the vitamins B, calcium, magnesium, potassium, iron, selenium and other nutrients. In this paper, the basic components of watermelon seeds, trace elements, the volatile components in roasted and raw watermelon seeds, extraction technology of oil from watermelon seeds, main physical and chemical of oil from watermelon seeds, the purification of unsaturated fatty by urea saturation method were researched. The experiments were provided certain theoretical basis for the processing of the watermelon seeds.The moisture content, oil and protein were determined by HS20-1multifunctional moisture meter, Soxhlet extractor and Kjeldahl method, respectively. The thousand seed weight of roasted and raw watermelon seeds were127.86g and125.32g. the ratio of nutlet and shell were76.06%and87.56%.The moisture contents were6.89%and4.47%.The crude fat contents were32.84%and36.37%.The protein contents were31.61%and29.57%.Through the method of flame atomic absorption spectrometry, the contents of K, Ca, Na and Mg were6.185mg/g,0.372mg/g,1.515mg/g,3.440mg/g in the watermelon seeds, and the contents of K, Ca, Na and Mg were1.09mg/g,0.187mg/g,0.255mg/g,0.505mg/g in the seeds without shell, respectively.The method of SDE was used to extact the volatile components in roasted and raw watermelon seeds. There were22and17kinds of components in the identified results of the roasted and raw watermelon seeds by GC-MS. The main volatile components in raw watermelon seeds were linoleic acid, palmitic acid, oleic acid, stearic acid and so on. The main volatile components in roasted watermelon seeds were bombykol,2,4-decadienal, palmitic acid, oleic acid, stearic acid and so on. The contents of the oleic acid and bombykol were increased after roasting.This shows that the roasted watermelon seeds have a large amounts of aroma compositions in farther production, and the main functional ingredients was not damaged basically. The watermelon seeds kept the original nutrition and the health value.This experiment studied on the influence of watermelon seeds oil extraction rate by soxhlet extraction, ultrasonic wave assisted extraction, water-bath extraction and static extraction respectively. The extraction rates were31.83%,26.38%,22.07%,17.95%. Then studied on the influence of watermelon seeds oil extraction rate by petroleum ether, normal hexane and ether, the extraction rates were22.29%,20.04%,17.84%. Based on single factor experiments, liquid/material ratio, ultrasonic time and different organic solvents were selected as influencing factors. Response surface methodology was used for optimizing the extraction technology of oil from watermelon seeds. The optimum extraction conditions were as follow:the liquid/material ratiol:16.3(g/mL), ultrasonic time45.4min, organic solvents were petroleum ether, ultrasonic temperature30℃, ultrasonic power250W. Based on the optimum extraction conditions, the verification extraction yield was28.04%. Get the quadratic equation model of watermelon seeds oil extraction and other factors variables in this experiment. The regression of this model was notability extremely; it was good to the experimental fit and had a certain useful value.The Analysis to the physical and chemical indexes of watermelon seeds oil were that: color flaxen, refractive index1.4630±0.0005, acid value0.254±0.020mgKOH/g oil, peroxide value1.81±0.10mmol/Kg, iodine value32.8～38.5g12/100g oil, saponification value199.8±5.0mgKOH/g oil.The unsaturated fatty acid of watermelon seeds oil was separated and purified by the urea saturation method. At the four process parameters conditions as fatty acids:urea, urea: ethanol, closure temperature, closure time by the orthogonal experiments, we can get the best conditions of the urea saturation unsaturated fatty acid as follows:the ratio of the mixture of fatty acid and urea is1:6, the ratio and ethanol is1:3(M/V), conditions is14℃, time condition is24h. Under these conditions, the iodine value of was89.57gI2/100g oil, and the coefficient of the unsaturated fatty acid was56.78%.