Physical Modification Of Dietary Fiber From Bamboo Shoot Shell And Its Effect On Physicochemical And Digestibility Of Lotus Root Starch

Starch is the main source of carbohydrate intake by the human body.However,in food industry applications,gelatinized starch is easy to age,has a short storage period,and has a high glycemic index,which affect the processing quality and practical value of starchy foods.Studies have shown that adding dietary fiber can increase the dietary fiber content in starch-based foods,improve the physical and chemical properties of starch paste,and slow down the rate of digestion.Bamboo shoot shell is a by-product of bamboo shoot processing,with abundant yield and low price.Therefore it is a good source of dietary fiber.However,the dietary fiber from bamboo shoot shell(BSSDF)has a rough taste and poor physicochemical properties,which limits its wide application in the food industry.In this study,BSSDF was modified by different ultrasonic pretreatments and high-pressure homogenization treatments to improve its physicochemical characteristics.Then the modified BSSDF is applied to lotus root starch to explore the effect of sexual conditions and addition ratio of BSSDF on the physicochemical properties and digestibility of lotus root starch.The main research contents and results are as follows:(1)The effect of ultrasonic treatment with different power and high pressure homogenization on the physicochemical properties of BSSDF was explored.The results showed that: with the increase of ultrasonic power,the breaking degree of dietary fiber increased,the particle was refined,and the water holding capacity,oil holding capacity and expansion capacity were significantly improved(P < 0.05),especially at 960 W,which increased by 120%,179% and 230% compared with those without ultrasonic pretreatment;Fourier transform infrared spectroscopy showed that there was no new absorption peak of BSSDF before and after modification;Scanning electron microscopy showed that the degree of breakage of the BSSDF increased,the flaky structure was more dispersed,and the degree of defibrillation increased;XRD results showed that the crystallinity of BSSDF increased at first then decreased with the increase of ultrasonic power,reaching the maximum at 720 W;TGA and DSC results showed that the thermal stability of BSSDF decreased,which was closely related to crystallinity;monosaccharide composition analysis showed that the type of monosaccharide composition remained the same,consisting of six monosaccharides: arabinose,xylose,mannose,rhamnose,galactose and glucose.(2)Taking lotus root starch as raw material to study the effect of modified BSSDF with different ultrasonic power(0 W,240 W,480 W,720 W and 960 W)on the gelatinization,viscosity,rheological,thermal characteristics and crystal structure and microstructure of lotus root starch.The results showed that the modified BSSDF could significantly influence the gelatinization characteristics of lotus root starch,which included gelatinization viscosity increasing and the disintegration value increases,which indicated that the mixed gel system of lotus root starch and modified BSSDF was not suitable for continuous thermal shear processing.The regeneration value decreased,indicating that the modified BSSDF had a certain inhibition effect on the short-term aging of lotus root starch.Lotus root starch is a pseudoplastic fluid,whose viscoelasticity and shear stability were enhanced,after the modified BSSDF added.DSC results showed that the gelatinization enthalpy of the lotus root starch compound system gradually increased.SEM results showed that the surface pores of the BSSDF/lotus root starch compound system became smaller,indicating that the modified BSSDF can inhibit the weight of amylopectin.Crystallization effectively delayed the long-term aging of lotus root starch.(3)The effect of different addition ratios(0%,3%,6%,9% and 12%)of the modified BSSDF on the physical and chemical properties of lotus root starch was studied.The results showed that with the increase of the addition ratio,the gelatinization viscosity of lotus root starch first increased and then decreased;the disintegration value increased,indicating that the stability of lotus root starch paste decreased;the regenerative value reached the lowest when the supplemental proportion was 9%,which was 42.69% lower than that of lotus root starch,indicating that the modified BSSDF had a certain inhibitory effect on the short-term aging of lotus root starch.Lotus root starch is a pseudoplastic fluid,whose viscoelasticity and shear stability were enhanced when modified BSSDF was added.DSC results showed that the enthalpy value of the lotus root starch compound system gradually decreased with the increase of the modified BSSDF addition.SEM results showed that the different addition ratios of modified BSSDF had different effects on the morphology of the compound system obvious.(4)The effects of high pressure homogenized BSSDF treated with different ultrasonic power(0 W,240 W,480 W,720 W and 960 W)on starch digestibility of lotus root were compared.The results showed that with the increase of ultrasonic power,the modified BSSDF could increase the proportion of resistant starch in the regenerated lotus root starch samples,and slow down the digestion rate of lotus root starch.At the same time,the study showed that the proportion of dietary fiber of modified bamboo shoot shell had a significant effect on the digestibility of lotus root starch.With the increase of the adding proportion,the digestion speed of the gelatinized lotus root starch decreased firstly and then increased,and the slowest rate was at 9%,indicating that the combination of modified bamboo shoot shell dietary fiber and lotus root starch was the closest at this time,which was consistent with the law measured in RVA.