| Yam is a kind of medicinal and at the same time it is also a kind of edible food.It is favored by consumers,because it is good for spleen、kidney health. In this study, we use three different kinds of yam as the main research object analyzing its main nutrients.Meanwhile, we extract three kinds of starch form Hainan local yam,studying its physical and chemical properties and processing characteristics.On this basis,we elected one kind of yam that relatively is used for processing into berverage varieties of yam and optimizing the best parameters that is used for producting of compound beverage.Results showed that:1.The basic nutritional analysis: The three kinds of fresh yam respectively contained water were 80.49%,78.06%,71.35%; protein were 2.43%,2.06%,1.93%;starch were 18.7%,17.3%,15.9%; In which the amylase content were 22.34%、27.43%、34.29%.2.The study of apparent structure and polymorph of three kinds of yam starch:By using a scanning electron microscope,we can observe the apparent of three kinds of yam starch granules.Cloud huai No.1,2 starch granules were relatively similar.The Cloud huai No.l relatively uniform in size and the surface was smooth.The size of Cloud huai No.3 was different from each other.Some of it is very small.The surface of it was relatively the most rough with some cracks on it.Using polycrystalline X-ray diffractometer to determinate three kinds of yam starch,we can see that the Cloud Huai No.1,2 starch both were belong to the C-type,and the Cloud huai No.3 starch belongs to the A-type.3.The study of physicochemical properties of three kind of yam:(1) The solubility of Cloud huai No.1,2,3 starch are all increasing with the increase of temperature. While the solubility of Cloud huai No.l is slightly higher than the cloud huai No.2 starch paste, which was significantly greater than the Cloud huai No.3 starch paste, were 14.55%,13.87%,7.84%;The overall swelling power of the starch paste was low, cloud Huai starch expansion was significantly higher than the other two limited expansion starch, was 30.34%. (2)The stability of three starch paste: Cloud huai starch No. 1(the change of transmittance was 16.92%)>Cloud huai starch No.3(the change of transmittance was 46.05%)> cloud huai starch No.2(the change of transmittance was 55.47%). After standing for 48 hours,the transmittance of three kinds of starch were: Cloud huai starch No.1 was 7.12%> Cloud huai starch No.2 was 6.68%> Cloud huai starch No.3 was 1.98%. (3) The retrogradation characteristics of three yam starch paste:cloud huai starch No.3 paste retrogradation> cloud huai No.1, 2 starch. (4) The comparison of the freeze-thaw stability:Cloud huai No.l>Cloud huai No.3>Cloud huai No.2.Meanwhile, analysis thermal characteristics of three yam starch by using differential scanning calorimetry, the results showed that: the gelatinization temperature of cloud huai No.1,2 starch is close and the cloud huai No.1 is higher, respectively 68.44℃,67.60℃,81.08℃.Among them,the largest starch phase transition temperature range is cloud huai No.2 (Tc-To,17.51℃) and the smallest is Cloud huai No.3(Tc-To,10.11℃). The three kinds of yam starch gelatinzation enthalpy were: cloud huai No.3>cloud huai No.2>Cloud huai No.1.In addition,studied the yam starch pasting properties and the feed additives on its characteristics by using rapid viscosity analyzer, results showed that:(1) When the concentration of yam starch is 6%, three kinds of starch of paste temperature is as follows:cloud Huai starch into a paste temperature of 85.4℃ into a paste of cloud Huai temperature of 81.8℃ > Cloud Huai No.1 into a paste 80.2℃ C; peaks in chronological order: cloud Huai cloud Huai 2> cloud Huai on the 1st; highest viscosity value size:cloud Huai 2 starch viscosity 1957cp> Cloud Huai starch viscosity 1729cp> Cloud Huai 3 starch viscosity 1572cp; return value: Cloud Huai 3 starch return value significantly smaller than the cloud Huai No.1, No.2 starch; the breakdown: Cloud Huai 3 starch significantly lower, cloud Huail,2, and Huai-3, starch paste, thermal stability is relatively good. (2) When the starch in the range of 4% to 12% starch concentration changes of yam starch RVA value has little effect. (3) When the NaCl amount is in the range of 2% to 7%, NaCl can increase the peak viscosity of the the cloud huai starch paste, trough viscosity, temperature into a paste, to extend the starch paste to achieve the highest viscosity peak time, improve cold starch paste viscosity stability, while the decreased stability of the starch thermal paste. While improving cloud huai 2,3 starch, starch paste, hot paste stability. (4) When the sucrose concentration is 3% to 9%, sucrose can be improved the three yam starch paste peak viscosity, trough viscosity, temperature into a paste, the deferral of starch paste to the highest viscosity peak time, to improve starch paste cold viscosity stability, the same time, so that the shear resistance and heat capacity of the starch paste decline. (5) When the pH= 6, the cloud huai No.1 and No.2 cloud huai starch paste, thermal stability and cold viscosity stability significantly greater than the higher than pH= 4, and other characteristic values did not change significantly. Relatively when the pH= 6 of cloud huai 3 starch,the peak viscosity, trough viscosity less than pH= 4, and other characterized values did not change significantly.4.The experimental studied the influence of liquefaction affecting,such as the slurry water ratio, reaction temperature, enzyme dosage, reaction time, pH and other factors were studied, and through the design of response surface methodology to optimize the conditions of the enzymatic hydrolysis of starch. The results show that:When using 1:9 water ratio beating, hydrolysis temperature 60℃, the amount of enzyme 34U/g raw materials, liquefaction time 127min, the DE can be the highest value. At the same time, by controlling the degree of hydrolysis to control the distribution of the DE value to obtain a different degree of hydrolysis yam drinks. It was found that the degree of hydrolysis of starch and the process can significantly affect the flavor of the beverage.Therefore,draw the conditions by further studing considering the beverage flavor quality and stability of enzymatic hydrolysis that:when the temperature is 60℃ , the enzyme dosage is of 34 U/g raw material, react 60min can achieve better enzymatic.5.The production process of yam beverage:In the process of yam beverage,thest ability is always a key issue. After a long-time storage, is easy to prone hie-rarchical precipitation, and aging the flocculation phenomenon that can seriouslyaffect the appearance of product quality and commercial value. In this study, using fuzzy comprehensive evaluation value indicators,get the optimal formula:add 7% sugar in the 10% yam paste,keep pH at 6.7 to 6.8. On the basis of the recipe, record beverages allowed to stand at room temperature for 7 days after the turbidity, and the stand for precipitation rate and viscosity. First, select the most beneficial to increase the stability of the beverage three stabilizersand their dosages from six bean gum stabilizer, and then optimized by orthogonal experiment to determine the stabilizer complex program:0.10% xanthan gum melon ch-ild bean gum,0.10% and 0.05% CMC. Beverage pH value was controlled between 6.7 to 6.8, colloid milling one time, homogenizate twice at the temperature of 75-85℃ and 25 MPa, then sterilization at 110℃ for 15 min, a uniform and stable yam beverage can get.6.Yam coconut milk compound beverage research:Combined with the characteristics of the product itself, local characteristics, study the compound beverag optimization formula: the amount of sugar 7%,yam drinks:coconut milk= 4:1,the stable is contained 0.10% CMC、0.10% melon child bean gum,0.15%xanthan gum. Yam-coconut milk compound beverage is flavor and nutrient-rich, white color, soft texture, and has broad market prospects. |
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