White waxy wheat: the new waxy wheat bred in Shandong Agricultural University. Glutinous rice flour purchased from a local market in Shandong province of China was sieved into a particle size of 100 μm. α-amylase with enzyme activity 2000 U/g. Glucamylase with enzyme activity 120,000 U/g. Analytically pure sodium acetate, benzoic acid, glacial acetic acid, sodium potassium tartrate, sodium hydroxide, 3,5-dinitrosalicylic acid, phenol, sodium sulphite and glucose.

We choose no mildew and no sprout wheat, after 80 mesh sieve to remove the impurities. Millet grains were thoroughly cleaned by removing unviable seeds and then washed with cold tap water and thoroughly rinsed with distilled water, then the water was drained and grains were solar dried, milled,

Solubility and swelling power of white waxy wheat flour and glutinous rice flour were determined as follows. Add 1 g white waxy wheat flour and glutinous rice flour to centrifuge tube and transfer purified water to a 50 mL volumetric flask. Then heated at the temperature of 50˚C, 60˚C, 70˚C, 80˚C, 90˚C in electronic oscillator for 30 min, after this, this samples should be centrifuge at 3000 r/min for 20 min, water bath the supernate and dry to constant weight at 105˚C. At last, the solubility and swelling power can be calculated.

Paste retrogradation characteristic of white waxy wheat flour and glutinous rice flour were analyzed according to GB/T24853―2010 [8] .

Paste transparency, freezing and thawing stability of white waxy wheat flour and glutinous rice flour were analyzed according to the method described by Ma et al. [9] .

Water-retaining capacity of white waxy wheat flour and glutinous rice flour were measured according to the

method of AACC 56-20 with some modifications. 10 mL distilled water was added into a centrifuge tube A (g) containing 0.1 g sample, heated at a specific temperature (70˚C, 80˚C, 90˚C) in a water bath for 1 h, centrifuged at 3000 r/min (TG1650-WS, Shanghai) for 20 min. Discarded the supernatant and weigh the gel B (g). The water-retaining of flour was calculated by

Digestibility of white waxy wheat flour and glutinous rice flour were determined according to the methods described by Miao et al. [10] . The glucose standard curve is presented in Figure 1.

The digestibility of white waxy wheat flour and glutinous rice flour were examined by rapid digestive starch (RDS), slow digestive starch (SDS) and resistant starch (RS) using the following equations:

where G₂₀ is the total glucose content (mg) after enzyme hydrolysis 20 min; TS is the total starch content (mg) of sample; FG is the glucose content (mg) before enzyme hydrolysis; G₁₂₀ is the total glucose content (mg) after enzyme hydrolysis 120 min.

6% (W/V) soluble starch was prepared by adding 50 mL distilled water into sample 3.00 g, gelatinized by heating in a water bath for 30 min, then cooling down to room temperature. A certain amount of sample was added into a centrifuge tube, frozen at −18 - −20˚C in a refrigerator for 24 h, unfroze in room temperature, centrifuged at 3000 r/min (TG1650-WS, Shanghai) for 20 min. Discarded the supernatant and weigh the precipitate. The water segregation rate (better Freezing and thawing stability with lower water segregation rate) of flour was calculated by the following equations:

Water segregation rate = (soluble starch weigh − precipitate weigh)/soluble starch weigh × 100%.

Paste retrogradation characteristics of white waxy wheat flour and glutinous rice flour were determined according to the methods described by Ding [11] .

All of determinations were done triplicates and calculated the averaged. SPSS software version 16.0 and sigma plot 10.0 was used to evaluate the analysis (ANOVA) and draw the figures, respectively.

Interaction between starch and water can be reflected by solubility. As shown in Figure 2, both the solubility of two samples increased with the increasing temperature. It is due to the liquid water associate together loosely with hydrogen bond, the proportion of single molecule water increase with higher temperature, then quantity of the starch molecule which participate in dehydration increase accordingly [12] . The solubility of white waxy wheat flour is lower than that of glutinous rice flour when the temperature is lower than 60˚C and whereas in the temperature higher than 60˚C. The possible reason is that wheat gluten reticular structure formed by water absorption of gliadin and glutenin in flour hindered the starch dissolution. Water absorbing capacity of starch suspension liquid in the gelatinization and water-retaining capacity centrifuged under a certain conditions can be reflected by swelling properties which also could be describe the gelatinization properties of starch. It can be observed from Figure 3 that the swelling power of white waxy wheat flour and glutinous rice flour increases with temperature rise.

A number of factors contributed to the gelatinizatin properties such as source, particle morphology, grain diameter, relative molecular weight and the proportion between amylose and amylopectin. Variations were obvious between the gelatinizatin properties of white waxy wheat flour and glutinous rice flour as shown in Table 1. There are higher peak viscosity, trough viscosity, breakdown, final viscosity, setback and peak time in

glutinous rice flour, indicating it has better water combining capacity, fast rate and large extent of decay, poor anti-shearing and heat-resistant quality, and better gelatination after cooling while worse ageing resistance in glutinous rice flour. Compared with it, white waxy wheat has lesser breakdown and setback, indicating that the swelled starch has better particle strength which not easy to break, better anti-shearing and heat-resistant quality, worse gelatination but better ageing resistance.

As far as the results that white waxy wheat has higher pasting temperature than glutinous rice flour, it may be mainly influenced by the molecular weight of white waxy wheat is much bigger than that of glutinous rice flour.

Swelling and distribution degree of starch granule in water were reflected by transparency. Transparency is higher with unanimous distribution and strong hydroscopicity, whereas transparency is lower by the reflection, refraction and diffusion of the light passed through due to the insufficient swelling, uneven distribution or retrogradation resulting in flocculation of starch in solution [13] . Transparency is one of the important external characteristics of starch paste which relates directly to the appearance and use of starch product, and then affects the acceptability of product [14] .

It can be seen in Table 2, the transparency of white waxy wheat flour significantly lower than that of glutinous rice flour. It maybe due to there were a small quantity of bran in the wheat flour, which had reflection, refraction and diffusion of the light passed through, resulting in lower transparency. During the storage period, the both transparency of two samples reduced, maybe related to the retrogradation which has negative correlation with transparency. Compared with white waxy wheat flour, glutinous rice flour has worse stability transparency attributed to it has relative smaller molecular weight easily formed network structures such as hydrogen bond then reduce the transparency.

Water-retaining capacity has a significant effect on shape and structure preserving of white waxy wheat flour and glutinous rice flour food product. As shown in Figure 4, there is no significant difference between tow samples at room temperature while white waxy wheat flour has lower water-retaining capacity than that of glutinous rice flour at higher temperature. Both of them increase with increasing of the temperature. The reason of water-retaining capacity increase at high temperature should be that starch lose crystallinity for high temperature, more hydrone permeate into and hydrate freely with starch molecules nearby microcrystal resulted in increase of water-retaining capacity.

Frozen foods should maintain original structure after storing in cold condition or freezing and thawing many times. So the starch paste used in frozen foods were required good freezing and thawing stability which is better with more freezing and thawing times and lower water segregation rate. Water precipitation appeared until in the second time of white waxy wheat flour and glutinous rice flour’s unfreeze procedure (Figure 5). The higher water segregation rate of white waxy wheat flour after same freezing and thawing times than that of glutinous rice flour indicated that it had a better freezing and thawing stability than glutinous rice flour.

Englyst et al. [15] felled starch into three categories by the character of digestion and absorption in the human

body: Rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS).

As shown in Table 3, white waxy wheat flour had higher RDS, SDS and lower RS than glutinous rice flour which indicating that white waxy wheat flour is easily digestible.

The heat absorbed in crystal melting and gave off in crystal formation can be measured by DSC. The content of crystal was determined by caloric content comparison indicating that higher caloric content of samples means higher crystallinity they had. Retrogradation is a reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves, causing the liquid to gel. The change trend of thermodynamic parameters such as the initial temperature T₀, the peak temperature T_p, the finishing temperature T_c and the caloric content ΔH were shown in Table 4. The results show that the T₀ and T_c of both samples are approximately same, T_p and enthalpy ΔH of white waxy wheat flour were higher than that of glutinous rice flour respectively during the gelatinizing phase possibly because white waxy wheat flour had higher particle crystallinity.

None retrogradation of white waxy wheat flour and glutinous rice flour was detected in the first and the third day. White waxy wheat flour had lower retrogradation characteristics than glutinous rice flour around the same time declaring that white waxy wheat flour has good ageing resistance.