Physicochemical studies of nanocrystals of starches from two rice (Oryza sativa L.) types and their characteristics using various modern instrument techniques

Abstract

BACKGROUNDStarch nanocrystals have received considerable attention, due to their biodegradability, nontoxicity and renewable and abundant sources. The objective of this research is to compare the morphology, physicochemical characteristics and rheological properties of native (NSNC) and waxy rice starch nanocrystals (WSNC).RESULTSBoth NSNC and WSNC exhibited a platelet‐like shape, and they tended to show square‐like platelet morphology with increasing initial amylopectin content. Compared to native starches, three weight loss stages of NSNC and WSNC in thermogravimetric analysis curves were observed, while the thermal depolymerization of NSNC started earlier than that of WSNC. The relative crystallinity of NSNC and WSNC was 38.6% and 48.3%, respectively, which were markedly higher than that of native starches. Fourier transform infrared spectra revealed that NSNC presented the highest ratio of 1045/1014 cm−1 bands among the tested samples, which was probably due to the re‐association of retrograded amylose to double‐helices structure in NSNC. Moreover, the introduction of sulfur atoms on the surface of NSNC and WSNC was confirmed from the results of X‐ray photoelectron spectroscopy. At 5% (w/v) and 10% (w/v) concentration levels, all SNC suspensions exhibited a shear‐thinning behavior as the shear rate increased from 0.1 to 100 s−1.CONCLUSIONSStarch nanocrystals obtained from native and waxy rice starch can be potentially used as reinforcement in biodegradable nanocomposites for packaging, fat replacers, thickening agents and emulsion stabilizers. © 2020 Society of Chemical Industry

Effect of Molecular Weight and Degree of Substitution on the Physical-Chemical Properties of Methylcellulose-Starch Nanocrystal Nanocomposite Films

“…FTIR spectra for MC films and MC-SNC nanocomposite films are summarized in Figure 4 . The band around 3441 cm −1 in all samples was attributed to O-H stretching vibration [ 16 ]. The bands at around 2973, 2932, 2903, and 2837 cm −1 were due to the symmetric and asymmetric stretching vibration of C-H bonds, while the bands around 1420 and 1374 cm −1 were determined by the deformation vibrations of CH 2 and bending vibration of CH groups, respectively, due to the presence of the CH 3 groups of MC and CH and CH 2 groups of SNC [ 29 ].…”

“…For the SNC spectrum, the absorbance bands at 1105, 1075, and 1059 cm −1 were attributed to the stretching vibration of C-C, bending vibration of C-O-H, and stretching vibration of C-OH, respectively. The bands at around 1048, 1013, and 995 cm −1 were due to the C-O-H, deformation vibration of C-OH, and bending vibration of C-O-C in the glucose ring, respectively, while 955 cm −1 was due to the coupled vibration of C-C and C-O [ 16 , 31 ]. Thus, a new band at around 1048 cm −1 was observed for all MC-SNC nanocomposite films ( Figure 4 C), which was associated with the ordered double helix structure of SNC [ 16 ].…”

“…Three MC samples, with trade name of M20 (Sinopharm Chemical Co., Ltd., Shanghai, China), A4C, and A4M (Ashland Co., Shanghai, China), were used as received from the manufacturers. Waxy rice starch SNC was prepared using the method reported by our previous study [ 16 ]. Sulfuric acid, NaNO 3 , methylbenzene, o-xylene, adipic acid, hydroiodic acid, and methyl iodide (Aladdin Bio-Chem Technology Co., Ltd., Shanghai, China) were used as received from the manufacturers.…”

“…In our previous study, SNC from waxy rice starch displayed a square-like platelet morphology with a diameter distribution range from 85.24 to 182.48 nm, while it showed an A-type crystalline structure with a highly crystalline nature [ 16 ]. Thus, this SNC could potentially be the promising nanofillers for reinforcement of polysaccharide films.…”

Effect of Physical Pretreatments on the Hydrolysis Kinetic, Structural, and Thermal Properties of Pinhão Starch Nanocrystals

“…[ 2–5 ] Acid hydrolysis process could be divided into two phases: first 2 days belonging to the first phase, and the last 3 days belonging to the second phase. [ 6,7 ] The regular yield is about 15%, after 5–40 days of hydrolysis, with size ranging from 20 to 450 nm [ 3–5,8,9 ] and crystallinity around 28%–58%, [ 9–11 ] with variations depending on the botanic origin and amylose content. [ 12 ] Widespread use of starch nanocrystals is currently limited due to the long preparation time and low yield.…”