Effect of starch concentration and resistant starch filler addition on the physical properties of starch hydrogels

Effect of freezing rates on α-amylase enzymatic susceptibility, in vitro digestibility, and technological properties of starch microparticles

The aim of this study was to evaluate the effect of freezing rates using direct (LF: Liquid nitrogen) and indirect (RF: Cryogenic refrigerator and UF: ultra-freezer) methods at temperatures of (-20, -80, and - 196 °C) on the enzymatic susceptibility with α-amylase for microparticles. In vitro digestibility parameters and technological properties were also analyzed. Lower rates resulted in larger ice crystals, damaging the starch structure. Hydrolysis was more pronounced at slower rates RF: 0.07 °C/min and UF: 0.14 °C/min, yielding maximum values of RDS: 37.63% and SDS: 59.32% for RF. Type A crystallinity remained unchanged, with only a noted increase in crystallinity of up to 6.50% for FR. Starch pastes were classified as pseudoplastic, with RF exhibiting superior textural parameters and apparent viscosity. (RF: 7.18 J g-1 and UF: 7.34 J g-1) also showed lower values of gelatinization enthalpy. Freezing techniques were viable in facilitating the diffusion of α-amylase and reducing RS by up to 81%.

Different effects of pea protein on the properties and structures of starch gel at low and high solid concentrations

In the context of starch-protein composite gels, the influence of protein on gel formation significantly shapes the textural attributes of starch gels, leading to distinct outcomes. This study aimed to evaluate how different ratios of pea protein (PP) affect the properties and structures of starch-protein composite gels at low (10 wt%) and high (40 wt%) solid concentrations. The addition of PP had opposite effects on the two gels. Compared to the pure starch gel, the low-concentration composite gel (LCG) with 20 % PP experienced a 48.90 ± 0.33 % reduction in hardness, and the storage modulus (G') decreased from 14,100 Pa to 5250 Pa, indicating a softening effect of PP on LCG. Conversely, the hardness of the high-concentration composite gel (HCG) with 20 % PP exhibited a 62.19 ± 0.03 % increase in hardness, and G' increased from 12,100 Pa to 41,700 Pa, highlighting the enhancing effect of PP on HCG. SEM and fluorescence microscopy images showed that PP induced uneven network sizes in LCG, while HCG with a PP content of 20 %, PP, together with starch, formed a three-dimensional network. This study provides valuable insights and guidance for the design and production of protein-enriched starch gel products with different textural properties.

Structure and properties of starch - BaSO4 composite obtained using mechanical activation techniques

The aim of this study is to obtain and characterize starch films structurally modified by in situ precipitation of BaSO4 combined with mechanical activation of casting dispersion in a rotor-stator device. By the rheological method, it was found that the modification causes a decrease in the ability of casting dispersions to structure over time. Composite films with a filler content of 0 %-15 % (w/w) were characterized using optical and SEM microscopy, FT-IR spectroscopy, and tensile and moisture resistance testing data. The maximum increase in strength (by 70 %) and elongation at break (by 870 %) is achieved with a filler content of 5 % and 15 %, respectively. An increase in the filler content to 5 % causes an increase in starch recrystallization rate, but at concentrations above 5 % of BaSO4, it inhibits retrogradation. The films obtained by mechanical activation with optimized parameters were uniformly translucent, had lower water vapor permeability than films made from starch alone, had high flexibility, and did not warp or shrink. The developed high-performance, environmentally friendly method can be recommended for the large-scale production of starch-based composite materials.

Development of Novel Cornstarch Hydrogel-Based Food Coolant and its Characterization

The food, pharmaceutical, and supply transport storage chain is seeking coolants that come with plastic-free packaging, are nontoxic, environmentally friendly, robust, reusable, and reduce water waste. To meet this demand, a new food coolant based on cornstarch hydrogel was developed and tested using the regeneration method. This study investigated the reusability, water retention, rehydration, and surface cleanliness of the hydrogel, along with its application in freshness retention for fruits. The results of the gel strength and differential scanning calorimetry (DSC) analysis showed that the ideal concentration of cornstarch hydrogel was 8%. Freezing and thawing experiments demonstrated that the hydrogel had the potential to be used as a cooling medium for refrigerated fresh foods. Moreover, the gel strength, scanning electron microscopy images (SEM), DSC, and thermogravimetric analysis (TG) revealed that the freeze-thaw reuse only slightly affected its freezable water content and that its gel strength gradually increased during reuse. Water retention and rehydration tests showed that the hydrogels could be better preserved at -20 °C compared to 4 °C, and the water lost during reuse could be replenished through rehydration. The flexibility in terms of shape and size also allows the hydrogel ice to be used as a customized coolant for various food shapes, as demonstrated by preservation experiments. Additionally, washing the hydrogel after each use can result in a significant reduction in Escherichia coli, Salmonella, and Staphylococcus aureus concentrations by 3.03, 3.47, and 2.77 log CFU/hydrogel, respectively. Overall, the new cornstarch hydrogel coolant is a promising alternative to conventional ice, with the potential to serve as a food coolant.

Physicochemical properties, in vitro digestibility, and pH-dependent release behavior of starch-steviol glycoside composite hydrogels

Steviol glycosides possess Bola-form amphiphilic structure, which can solubilize hydrophobic phytochemicals and exert physical modification to the hydrophilic matrix. However, the effect of steviol glycosides on the starch hydrogel is still unclear. Herein, the physicochemical properties, in vitro digestibility, and release behavior of starch hydrogel in the presence of steviol glycosides were investigated. The results showed that the addition of steviol glycosides promoted the gelatinization and gelation of starch, and endowed the starch hydrogel with softer texture, larger volume, and higher water holding capacity. The hydrophobic curcumin was well integrated into hydrogel by steviol glycosides, providing the gel with improved colour brilliance. The introduction of steviol glycosides hardly affected the digestibility of starch gel, but it promoted the release rate of curcumin. Notably, this release behavior was pH dependent, which tended to target the alkaline intestine. This work provided some theoretical supports for the development of sugar-free starchy foods.

Green banana flour as a novel functional ingredient in retorted feline diets

Green banana flour (GBF) is a novel ingredient that is high in resistant starch and could be a dietary fiber source in companion animal nutrition. In addition, with its light brown color and pectin content, GBF could potentially serve as a natural color additive and thickening agent in pet food manufacturing. The purpose of this research is to evaluate different sources of GBF, the effect of GBF on texture and color in canned foods, and its effect on apparent total tract digestibility (ATTD), fecal characteristics, and fecal fermentative end-products in healthy adult cats. Prior to the feline study, different sources of GBF were analyzed for chemical composition, manufacturing properties, true metabolizable energy, and fermentability. For the feline feeding trial, all treatment diets were formulated to meet or exceed the Association of American Feed Control Officials (Association of American Feed Control Officials (AAFCO) 2020. Official Publication. Champaign, IL.) guidelines for adult cat maintenance. There were five dietary treatments: rice control (4% rice flour), potato control (4% dehydrated potato flakes), 1% GBF (1% GBF and 3% rice flour), 2% GBF (2% GBF and 2% rice flour), and 4% GBF. All treatment diets were analyzed for texture and color. The animal study was conducted using a completely randomized design with 39 adult domestic cats. There was a 7-d diet adaptation period followed by a baseline fresh fecal collection to determine fecal score, pH, short-chain fatty acid, branched-chain fatty acid, phenol, indole, ammonia, and microbiota. The treatment period lasted for 21 d and a total fecal collection was performed during the last 4 d of this period to determine the ATTD. A fresh fecal sample was also collected during the total fecal collection to evaluate fecal score, pH, metabolites, and microbiota. The MIXED model procedures of SAS version 9.4 were used for statistical analysis. Treatment diets containing GBF had a lower hardness from the texture profile analysis (P < 0.05). For color analysis, the 4% GBF diet was darker in color compared with the rice diet (P < 0.05). There was no difference in food intake, fecal output, or ATTD of macronutrients among the treatment groups (P > 0.05). There was no interaction of treatment and time or main effects shown in fecal score, pH, metabolites, or microbiota diversity (P > 0.05). In conclusion, adding GBF to canned diets may affect the texture and color of the product, but GBF was comparable to traditional carbohydrate sources, rice, and potato, from a nutritional aspect.

Characterization and Evaluation of Heat-Moisture-Modified Black and Red Rice Starch: Physicochemical, Microstructural, and Functional Properties

This study sought to evaluate starch from black and red rice modified by heat-moisture, investigating the extraction yield, starch and amylose content, color, and phenolic compounds. The water and oil absorption capacity, whole milk and zero lactose absorption index, syneresis index, and texture were also analyzed. Microstructural analysis included Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The heat-moisture treatment (HMT) reduced the extraction yield and the starch and amylose content, with native black rice starch having the highest values for these parameters. The modification also affected the color and phenolic compounds of the starch, making it darker and changing its appearance. The modification improved the absorption of water, oil, and milk, reducing syneresis and increasing stability during storage. The starch surface was altered, especially for modified black rice starch, with larger agglomerates. The type of starch also changed from A to Vh, with lower relative crystallinity. The textural properties of modified red rice starch were also significantly altered. The HMT proved to be a viable and economical option to modify the analyzed parameters, influencing the texture and physicochemical properties of pigmented rice starch, expanding its applications, and improving its stability during storage at temperatures above 100 °C.