Comparison of the structural characterizatics and physicochemical properties of starches from sixteen cassava germplasms cultivated in China

Effect of continuous instant pressure drop treatment on the rheological properties and volatile flavor compounds of whole highland barley flour

Continuous instant pressure drop (CIPD) treatment effectively reduces microbial contamination in whole highland barley flour (WHBF). Base on it, this study further investigated its effects on flour properties (especially rheological properties) and volatile compounds (VOCs) profile of WHBF, and compared it with that of ultraviolet-C (UV-C), ozone and hot air (HA) treatments. The results showed that the damaged starch content (6.0%) of CIPD-treated WHBF was increased, leading to a rough surface and partial aggregation of starch particle, thereby increasing the particle size (18.06 μm of D10, 261.46 μm of D50 and 534.44 μm of D90). Besides, CIPD treatment exerted a positive influence on the structure and rheological properties of WHBF, including an elevation in pasting temperature and viscosity. Notably, CIPD-treated WHBF exhibited higher storage modulus and loss modulus compared to the other three groups of sterilization treatments, contributing to the formulation of a better-defined and stable gel strength (tan δ = 0.38). UV-C and ozone, as cold sterilization techniques, also induced alterations in specific characteristics of WHBF. UV-C treatment led to changes in WHBF's crystallinity, while ozone treatment caused modifications in the secondary protein structure of WHBF. A total of 68 VOCs were identified in raw WHBF (including 3 acids, 19 alcohols, 25 aldehydes, 1 alkene, 8 esters, 2 ethers, 3 furans, and 7 ketones). The maximum flavor-contributing VOC in CIPD-treated WHBF remained dimethyl sulfide monomer (cabbage aroma), consistent with the raw WHBF. Conversely, in HA-treated WHBF, the maximum flavor-contributing VOC shifted to 2-furanmethanethiol monomer (roasted coffee aroma), altering the initial flavor presentation. These findings will provide strong support for the application of CIPD technology in the powdery foods industry.

The effects of heat-moisture treatment on resistant starch levels in cassava and on fermentation, methanogenesis, and microbial populations in ruminants

Background and Aim

Resistant starch (RS) is difficult to digest in the digestive tract. This study aimed to evaluate the effects of heat-moisture treatment (HMT) on RS in cassava and examined its impact on rumen fermentation.

Materials and Methods

Cassava flour was used as a raw material and used in a randomized block design with four different cycles of HMT as the treatments and four different rumen incubations in vitro as blocks. Treatments included: HMT0: without HMT (control), HMT1: one HMT cycle, HMT2: two HMT cycles, and HMT3: three HMT cycles. Heat-moisture treatment processes were performed at 121°C for 15 min and then freezing at -20°C for 6 h. Analyzed HMT cassava starch characteristics included components, digestibility, and physicochemical properties. In in vitro rumen fermentation studies (48 h incubation) using HMT cassava, digestibility, gas production, methane, fermentation profiles, and microbial population assessments were performed.

Results

Heat-moisture treatment significantly reduced (p < 0.05) starch, amylopectin, rapidly digestible starch (RDS), and slowly digestible starch levels. In contrast, amylose, reducing sugars, very RDS, RS, and protein digestion levels were significantly increased (p < 0.05). Additionally, a reduced crystallinity index and an increased amorphous index were observed in starch using Fourier-transform infrared analyses, while a change in crystalline type from type A to type B, along with a reduction in crystallinity degree, was observed in X-ray diffraction analyses. Heat-moisture treatment significantly (p < 0.05) reduced rumen dry matter (DM) degradation, gas production, methane (CH₄ for 12 h), volatile fatty acid (VFA), and propionate levels. In addition, acetate, butyrate, and acetate/propionate ratios, as well as population of Streptococcus bovis and Bacteroides were significantly increased (p < 0.05). However, pH, ammonia, and organic matter digestibility were unaffected (p > 0.05) by HMT.

Conclusion

Cassava HMT altered starch characteristics, significantly increased RS, which appeared to limit rumen digestion activity, decreased rumen DM degradation, gas production, VFAs, and CH₄ production for 12 h, but increased S. bovis and Bacteroides levels.

New Model High Temperature Pasting Analysis of Fermented Cassava Granules

Cassava is a starchy food item eaten by millions worldwide in various forms. The product has been subjected to various analysis forms, including the viscosity capacity of different flours made from the product. In this study, cassava granules (Garri) were subjected to scanning electron microscopy (SEM) and laser diffraction particle size analysis to determine microstructure, after which the viscosity behavior was ascertained under high pressure with the new model high-temperature rapid viscosity analyzer (RVA HT 4800), which is capable of reaching a maximum of 140 °C. Viscosity comparisons were then made with the profiles obtained at 95 °C and 140 °C. The microstructure had intact starch cells and was free of extraneous materials or fungal hyphae. The granule size range was found to be 1–1800 µM. It was established that the holding, final, and setback viscosities were most affected and decreased by at least 80% when the samples were subjected to the 140 °C HT profile. The peak time at 95 °C in yellow and white Garri samples of both brands averaged nine minutes, whereas it was 5 min at 140 °C profile. The white Garri samples tolerated the high temperature better based on breakdown viscosity values and may be used for making food products that require tolerance to high temperatures. An opportunity exists to re-evaluate different Garri varieties with the new model RVA to establish behavior at very high temperatures.

Effect of drying treatment on the structural characterizations and physicochemical properties of starch from canistel (Lucuma nervosa A.DC)

This work investigated the effects of hot air drying pretreatment (HAD), freeze drying pretreatment (FD) and vacuum drying pretreatment (VD) on the physicochemical properties and structural characterizations of starch isolated from canistels. X-ray diffraction displayed that the starches separated from canistel by different drying pretreatments showed a typical A-type crystal structure. The SEM image showed that cracks and debris appeared on the surface of HVD and VD particles. The molecular structure of starches obtained by different drying pretreatments was studied using Fourier infrared and solid state ¹³C CP/MAS NMR analysis. The results indicated that vacuum drying pretreatment could promote the formation of the double helix of starch granules, and hot air drying and freeze drying destroyed the ordered structure of starch granules. These structural changed to affect the physicochemical properties of starch granules. The study of different drying pretreatments to separate starches provided practical value for drying pretreatments. Furthermore, the current study affords information for canistel starches cultivated in China that would be convenient for commercial applications.