Effect of microwave treatment on the physicochemical properties of potato starch granules

Abstract

BackgroundThe degree of polymerization of amylose starch in potato was so large that the gel was hardness after gelatinization. Therefore, it is one of the most important ways that the microwave treatment was used to change the physicochemical properties of starch gel to make it suitable for the preparation of instant food.ResultsThe effect of microwave treatment on the physicochemical properties including morphology, crystalline structure, molecular weight distribution and rheological properties of potato starch granules was evaluated by treating time of varying duration (0, 5, 10, 15, 20 s) at 2450 MHz and 750 W. Scanning electron micrographs (SEM) of potato starch granules showed flaws or fractures on the surface after 5 to 10s of microwaving and collapse after 15 to 20 s. Polarized light microscopy (PLM) indicated that microwave treating damaged the crystalline structure of potato starch, such that the birefringence of starch granules gradually decreased after 5 to 10s and even disappeared after microwaving from 15 to 20 s. The molecular weight (Mw) values of potato starch and the proportion of large MW fraction were considerably reduced with increasing the microwave treating time from 0 to 20s. The molecular weight slowly decreased over 5 ~ 15 s microwave treating but decreased abruptly at the time of 20s microwave treating. The apparent viscosity decreased as shear rate increased and presented shear-thinning behavior. The magnitudes of the storage modulus (G’) and loss modulus (G”) obtained at each shear rate increased with duration of microwave treating from 0 to 15 s but decreased from 15 to 20 s.ConclusionsThese results demonstrated that the morphology and crystalline structure was damaged by microwave treatment. The high molecular weight of potato starch above 2 × 108 Da was so sensitive to the vibrational motion of the polar molecules due to the application microwave energy and broke easily for longer dextran chains. The fracture of starch granules, molecular chains leached from the starch granules and degradation of dextran chains contributing to the development of rheological properties.

Prediction of the Postprandial Blood Sugar Response Estimated by Enzymatic Kinetics of In Vitro Digestive and Fine Molecular Structure ofArtocarpus heterophyllusLam Seed Starch and Several Staple Crop Starches

“…According to Zhang et al, Rg reflects the molecular size, indicating that JFSS has a relatively large molecular size. The M w values in RS and PS were 0.42 × 10 7 g mol −1 and 4.74 × 10 7 g mol −1 , respectively, similar to the results of Xie et al and Viturawong et al who reported that the M w of RS and PS were 4.05 × 10 6 g mol −1 and 4.59 × 10 7 g mol −1 , respectively . According to Liu et al, the M w , M n , and R g of cereal starches with A‐type crystalline structures were lower than those in starches with B‐type crystalline structures, such as bean starch .…”

Temperature‐responsive alginate‐g‐poly(N,N‐diethylacrylamide) copolymer: Synthesis, characterization, and swelling behavior

“…As shown in the figure, elution volume of graft copolymers shifted to higher values compared to that of alginate, which resulted in a significant decrease in the molecular weights as presented in Table . This result demonstrates that microwave irradiation used in the grafting reaction may cause cleavage of some bonds in the alginate chains . However, when grafting percentages increased from 58% to 88%, all types of average molecular weights increased proportionally, due to the formation of much longer PDEAAm chains in the copolymer structure.…”

Physical Modification of Food Starch Functionalities

“…Alternative HMT processing methods include reduced-pressure HMT (RP-HMT) (Maruta et al 1994;Bahrani et al 2012Bahrani et al , 2013, direct-vapor HMT (DV-HMT) (Bahrani et al 2012(Bahrani et al , 2013, and instantaneous controlled pressure drop (DIC, for détente instantanée contrôlée) processing (Maache-Rezzoug et al 2008, 2010Bahrani et al 2012Bahrani et al , 2013) (see Section 3.3.2), all of which involve direct steam injection under varied processing or pressure conditions. Other reported HMT processing adaptations include pre-or postannealing in conjunction with HMT (Stute 1992;Chung et al 2009aChung et al , 2010, dual-stage HMT (Klein et al 2013), use of microwave irradiation for rapid HMT treatment (Lewandowicz et al 1997;Stevenson et al 2005;Anderson & Guraya 2006;Luo et al 2006;Zhang et al 2009Zhang et al , 2010aXie et al 2013) (see Section 2.5), and use of aqueous alcohol as an HMT heating medium (Kurakake et al 1997). HMT may be conducted following pretreatment with an acid (Brumovsky & Thompson 2001, Shin et al 2004, under varied pH conditions (Kim & Huber 2013), or in the presence of high concentrations of a salt-termed osmotic pressure treatment (OPT) ) (see Section 2.6)-or xylitol (Sun et al 2014a).…”