The influence of rice protein content and mixed stabilizers on textural and rheological properties of jasmine rice pudding

Rheology and stability mechanism of pH-responsive high internal phase emulsion constructed gel by pea protein and hydroxypropyl starch

There is an increasing demand for stable, highly viscoelastic, and printable emulsion gels based on pea protein (PeaP) as a substitute for animal fat. In this article, a simple pH modulation strategy was applied to regulate high internal phase (HIPE) gels prepared from PeaP and hydroxypropyl starch (HPS). The results showed that the interfacial tension of PeaP decreased from 11.9 to 7.1 mN/m at 5% PeaP and from 9.9 to 6.3 mN/m at 10% PeaP with increasing pH from 7 to 11. The incorporation of HPS improved the strength and physical stability of the HIPE gel. HIPE gels showed the best three-dimensional printing ability at pH 11. The main mechanism of HIPE gels at pH 3 was hydrophobic interaction, while electrostatic interaction dominated at pH 7, 9, and 11. This study may provide insights into the development of PeaP-based HIPE gels as a printable fat alternative.

Evaluation of rheological, textural, and sensory characteristics of optimized vegan rice puddings prepared by various plant-based milks

Nowadays, plant-based milks are being considered as an alternative to dairy milk due to their advantages, such as sustainability, reduced allergenicity, health benefits, and lactose-free nature. Plant-based milks are widely used in the preparation of desserts, cheese-like products, and beverages, among other applications. The aim of the present study was to formulate vegan rice puddings using various commercially available plant-based milks as a sustainable alternative to dairy milk. For this aim, central composition design was applied to optimize the key processing parameters of the Thermomix®, including temperature (80-90°C), time (6-14 min), and the amount of rice flour (6-10%, w/v), using response surface methodology (RSM). According to the RSM results, the optimum conditions were found to be 90°C for 12.5 min with 6.5% rice flour, as they exhibited minimal phase separation and similar rheological and textural properties to dairy rice pudding. Soya milk pudding had the highest hardness value among the other plant-based milk puddings, and whole fat milk, soya, oat, coconut, and cow's milks showed the best gel unity, according to the cohesiveness results. Phase separation, an important parameter for storage stability, was not observed during 7-day storage at 4°C in all groups, except for pistachio milk rice pudding. Rheological results demonstrated that all vegan pudding samples exhibited a gel-like structure with storage modulus (G') exceeding loss modulus (G″) values. According to the descriptive sensory evaluation, coconut, oat, and soya milk rice puddings received the highest scores in overall acceptability. Our findings suggest that industrial plant-based rice puddings have great potential as a novel product that meets the dietary needs of the vegan community by offering acceptable flavor and texture.

The Microstructure, Rheological Characteristics, and Digestibility Properties of Binary or Ternary Mixture Systems of Gelatinized Potato Starch/Milk Protein/Soybean Oil during the In Vitro Digestion Process

The in vitro digestibility of potato starch-based foods interacting with milk protein and soybean oil was investigated. Microstructures and rheological changes upon digestion were determined. The results showed that the addition of milk proteins (casein and whey protein) promoted gelatinized potato starch digestion, while soybean oil slowed down gelatinized potato starch digestion. A mixture of soybean oil and milk protein promoted the digestion of milk protein, while a mixture of gelatinized potato starch and milk protein inhibited the digestion of milk protein. The mixture of milk protein and/or gelatinized potato starch with soybean oil promoted the release of free fatty acids in soybean oil. The highest release rate of free fatty acids was attained by a mix of milk protein and soybean oil. The mixed samples were digested and observed with a confocal laser scanning microscope. The viscosity of the digestates was determined by a rheometer. Overall, the results demonstrated that the addition of milk protein and soybean oil had an effect on the in vitro digestibility of gelatinized potato starch and its microstructure.

Quality characteristics of semi-glutinous japonica rice cultivated in the middle and lower reaches of the Yangtze River in China

BACKGROUND

Semi-glutinous japonica rice (SGJR) is increasingly a popular choice for rice consumption and more commonly cultivated in the middle and lower reaches of the Yangtze River in China. Here, 58 SGJR and 75 non-semi-glutinous japonica rice (NSGJR) cultivars were evaluated for their characteristics of grain quality by assessing the taste of cooked grains, flour/paste properties, chemical compositions and starch physicochemical properties.

RESULTS

Comparisons of factors related to taste showed that cooked rice characteristics of SGJR were better in appearance, lower in hardness, lower in springiness and higher in stickiness. There were no significant differences in contents of total starch and total protein between the two types of rice. Further analysis indicates that thinner lamellar thickness, smaller starch particle size, and higher contents of amylopectin and albumin of SGJR (resulting in higher weights of dried matter from rice slurries) contributed to better appearance of cooked SGJR. Lower contents of amylose and prolamin led to a weaker and less elastic gel network in rice paste samples and contributed to a stronger moisture migration capability of cooked SGJR that showed higher stickiness and lower hardness and springiness.

CONCLUSION

A SGJR line with low apparent amylose content does not indicate good taste. Physicochemical properties of starch and protein contributed to better appearance, higher stickiness and lower hardness and springiness of cooked SGJR. These findings provide empirical data to help breed better-tasting cultivars of japonica rice. © 2021 Society of Chemical Industry.

Development of low glycemic index instant Phirni (pudding) mix-its visco-thermal, morphological and rheological characterization

High amylose rice (HAR) and carboxymethyl cellulose (CMC) are the preferred choices for enhancement of resistant starch content and lowering of glycemic index in dairy desserts. The effects of different levels of skimmed milk powder (SMP): HAR flour (45:55 to 75:25) and CMC (0.1 to 1%) were investigated on physical characteristics of dry-mix and on texture profile parameters, resistant starch (RS), predicted glycemic index (pGI), glycemic load (GL) and overall acceptability of phirni (a traditional milk pudding). Design expert predicted SMP (70): HAR (30) and CMC (0.8%) as optimum levels for reducing the pGI and maximizing the RS content and other quality characteristics in phirni. RS content of phirni (4.38%) prepared from optimized dry-mix (ODM) was higher while pGI (48.12) and GL (7.50) were lower as compared to phirni prepared from market dry-mix (MDM). The visco-thermal properties of ODM and MDM also showed significant variations. Storage modulus (Gʹ) and loss modulus (Gʹʹ) indicated that ODM phirni was less solid than MDM phirni. Scanning electron micrographs showed fused structures in ODM, while coarse sheet like structures were observed across the surface of MDM. Thus, ODM can be a promising substitute for the available milk desserts for diabetic patients.

Differences in Eating Quality Attributes between Japonica Rice from the Northeast Region and Semiglutinous Japonica Rice from the Yangtze River Delta of China

Differences in cooked rice and starch and protein physicochemical properties of three japonica rice were compared systematically. Cultivars of japonica rice, Daohuaxiang2, from Northeast China (NR) and two semiglutinous japonica rice (SGJR), Nangeng46 and Nangeng2728, from the Yangtze River Delta (YRD) were investigated. Both Daohuaxiang2 and Nangeng46 achieved high taste values, but there were great differences in starch and protein physicochemical properties. Daohuaxiang2 showed higher apparent amylose content (AAC), lower protein content (PC), and longer amylopectin (especially fb2 and fb3) and amylose chain lengths, resulting in thicker starch lamellae and larger starch granule size. Its cooked rice absorbed more water and expanded to larger sizes. All of these differences created a more compact gel network and harder but more elastic cooked rice for Daohuaxiang2. Nangeng46 produced a lower AAC, a higher PC, shorter amylopectin and amylose chain lengths, thinner starch lamellae, and smaller starch granule sizes, creating a looser gel network and softer cooked rice. The two SGJR, Nangeng46 and Nangeng2728, had similar low AACs but great differences in taste values. The better-tasting Nangeng46 had a lower PC (especially glutelin content) and higher proportion of amylopectin fa chains, which likely reduced the hardness, improved the appearance, and increased the adhesiveness of its cooked rice. Overall, both types of japonica rice from the NR and YRD could potentially have good eating qualities where Nangeng46's cooked rice was comparable to that of Daohuaxiang2 because of its lower AC. Moreover, its lower PC and higher proportion of amylopectin fa chains likely improved its eating quality over the inferior-tasting SGJR, Nangeng2728. This research lays a foundation for the improvement of the taste of japonica rice in rice breeding.

Textural and structural properties of a κ-carrageenan-konjac gum mixed gel: effects of κ-carrageenan concentration, mixing ratio, sucrose and Ca2+ concentrations and its application in milk pudding

BACKGROUND

Mixtures of carrageenan and konjac gum are useful for specific applications in gel-based foods. Focusing on the changes of textural and structural properties, the effects of κ-carrageenan and konjac ratio and sucrose and Ca²⁺ concentrations on mixed gels were studied in this research. Furthermore, application of κ-carrageenan-konjac gum mixed gel to milk puddings was investigated.

RESULTS

There was a better synergistic effect when the ratio of κ-carrageenan and konjac was 7:3. The mixed gel containing 10 g kg^-1 κ-carrageenan-konjac gum was characterized by higher hardness, chewiness, adhesiveness and resilience and denser network structure. Besides, the addition of 5-10 wt% sucrose or 0.02 wt% Ca²⁺ could enhance the hardness, chewiness and adhesiveness of the mixed gel, as well as affording a denser network structure. For milk pudding, moderate hardness, chewiness and resilience could be obtained by adding 1.5 g kg^-1 κ-carrageenan-konjac gum mixture.

CONCLUSIONS

This research provides useful information for the formation of κ-carrageenan-konjac gum gel and its application in milk pudding. © 2020 Society of Chemical Industry.

Characteristics of pasting properties and morphology changes of rice starch and flour under different heating modes

The pasting behavior of rice starch and its relationship with cooking properties of rice have been extensively studied. However, the viscosity changes of rice starch and flour under conventional cooking mode and high temperature and high pressure (HTHP) mode remain unknown. In this study, three typical rice starches and seven rice flours of different types and varieties were used to evaluate the effect of cooking modes on their pasting behaviors. A detailed discussion about the relationships among chemical composition, thermal properties, and crystallinity were conducted to explain the different pasting behaviors of the rice samples. The pasting behavior of rice starch was found to be similar with rice flour under standard and conventional heating modes, while remarkably different when treated at different HTHP levels, especially for sticky rice flour. The morphological changes of rice samples at 95 °C and 120 °C confirmed that high temperature long time heating caused extending of molecules, which exhibited layered structure at 120 °C. The rice flour samples showed different morphologies after heating at different modes due to varied amylose content and crystallinity, which contributed to different pasting behavior. These results provide useful information for developing strategies to control rice cooking and improve eating quality.