Influence of corn resistant starches type III on the rheology, structure, and viable counts of set yogurt

Effects of water-soluble and water-insoluble α-glucans produced in situ by Leuconostoc citreum SH12 on physicochemical properties of fermented soymilk and their structural analysis

This study investigated the effect of in situ produced water-soluble α-glucan (LcWSG) and water-insoluble α-glucan (LcWIG) from Leuconostoc citreum SH12 on the physicochemical properties of fermented soymilk. α-Glucans produced by Leuc. citreum SH12 improved water-holding capacity, viscosity, viscoelasticity and texture of fermented soymilk. Gtf1365 and Gtf836 of the five putative glucansucrases were responsible for synthesizing LcWSG and LcWIG during soymilk fermentation, respectively. Co-fermentation of soymilk with Gtf1365 and Gtf836 and non-exopolysaccharide-producing Lactiplantibacillus plantarum D1031 indicated that LcWSG effectively hindered the whey separation of fermented soymilk by increasing viscosity, while LcWIG improved hardness, springiness and accelerated protein coagulation. Fermented soymilk gel formation was mainly based on hydrogen bonding and hydrophobic interactions, which were promoted by both LcWSG and LcWIG. LcWIG has a greater effect on α-helix to β-sheet translation in fermented soymilk, causing more rapid protein aggregation and thicker cross-linked gel network. Structure-based exploration of LcWSG and LcWIG from Leuc. citreum SH12 revealed their distinct roles in the physicochemical properties of fermented soymilk due to their different ratio of α-1,6 and α-1,3 glucosidic linkages and various side chain length. This study may guide the application of the water-soluble and water-insoluble α-glucans in fermented plant protein foods for their quality improvement.

The properties of the rice resistant starch processing and its application in skimmed yogurt

Extrusion is typically employed to prepare resistant starch (RS). However, the process is complicated. In this study, the effects of twin-screw extrusion on the crystallinity, thermal properties, and functional properties of starch formed in different extrusion zones were investigated. The effects of this process on the rheological properties and microstructure of RS-added skimmed yogurt were also studied. According to the results, the RS content increased from 7.40 % in the raw material to 33.79 % in the extrudate. The A-type crystal structure of the starch was not observed. The dissociation temperature of the extruded starch ranged from 87.76 °C to 100.94 °C. The glycemic index (GI) of skimmed yogurt fortified with 0.4 % RS was 48.7, and the viscosity was also improved. The microstructure exhibited a uniform network of the starch-protein structure. The findings may serve as a theoretical basis for the application of RS in the food industry.

Heat-moisture-treated rice starches with different amylose and moisture contents as stabilizers for nonfat yogurt

Food producers are interested in enhancing native starch properties without chemical modifications. Here, rice starches were physically modified via heat-moisture treatment (HMT) using different amylose (high, medium, low, and waxy) and moisture (15 %, 20 %, 25 %, and 30 %) contents. Hydration properties and pasting viscosities differed for different amylose and moisture contents. The HMT starch with high amylose content and 15 % moisture (High_HMT15) exhibited the highest final viscosity (6.16 Pa.s), and 31.7 % and 35.1 % increased amount of resistant starch compared to native starch in the granule and paste states, respectively. Hence, High_HMT15 was used as a stabilizer for nonfat yogurt. The nonfat yogurt prepared with 1.0 % High_HMT15 as the stabilizer exhibited 37.3 % reduced whey separation, 2.8 times increased viscosity, a high total solids content, and acceptable sensory properties compared to the nonfat yogurt without starch. These HMT starches can replace chemically modified starches derived from other grains in various food applications.

Formulations and assessments of structure, physical properties, and sensory attributes of soy yogurts: Effect of carboxymethyl cellulose content and degree of substitution

Soy yogurts present challenges, including absence of tender and slipperiness mouthfeel, and poor stability. This study aimed to investigate the impacts of carboxymethyl cellulose (CMC) with degrees of substitution of 0.7 (CMC0.7) and 1.2 (CMC1.2) at concentrations ranging from 0 % to 1.1 % on the stability, microstructure, rheology, tribology, and mouthfeel of soy yogurts. As the CMC concentration increased from 0 % to 0.3 %, soy yogurts displayed a coarser microstructure, decreased stability, and increased gel strength. As the concentration of CMC further increased from 0.5 % to 1.1 %, soy yogurts exhibited trends of a smoother microstructure, increased stability, and softer gel strength. Notably, soy yogurts with CMC0.7 demonstrated a superior water holding capacity (WHC) than soy yogurts with CMC1.2. Tribological measurements indicated that soy yogurts with CMC0.7 at a 0.7 % concentration had the lowest coefficient of friction (COF) value among most sliding speeds, showing a 23 % reduction compared to soy yogurts without CMC at a sliding speed of 10 mm/s. Moreover, sensory evaluation showed that soy yogurts with CMC0.7 at a 0.7 % concentration had the highest total score in mouthfeel evaluation. Therefore, the addition of CMC0.7 within the concentration range of 0.5 % to 1.1 % may produce stable and delicate yogurts.

Physical and Chemical Properties, Flavor and Organoleptic Characteristics of a Walnut and Purple Rice Fermented Plant Drink

In recent years, green and healthy foods have attracted much attention. Plant-based foods have become an alternative to animal-derived foods. In this study, we used walnut and purple rice as the primary raw materials to produce a fermented plant drink. The process included boiling, mixing, grinding, inoculation, fermentation, and sterilization. We then analyzed the similarities and differences between the resulting walnut and purple rice fermented plant drink and an unfermented walnut and purple rice plant drink, as well as dairy-based yoghurt, in terms of physical chemistry, flavor, and sensory characteristics. We also examined the similarities and differences between the walnut and purple rice fermented plant drink and room-temperature yoghurt. The study results revealed that the walnut and purple rice fermented plant drink exhibited greater viscosity than the walnut and purple rice unfermented plant drink and room-temperature yoghurt. Additionally, the former displayed enhanced stability and recovery ability. Notably, distinguishable differences were observed between the three samples in terms of the presence of unknown volatiles and the umami signal, as indicated by electronic nose/tongue and GC-IMS analyses. The umami flavor of the walnut and purple rice fermented plant drink surpasses that of room-temperature yoghurt, while its taste is less salty than that of the walnut and purple rice plant drink. Despite possessing a weaker aroma than dairy-based yogurt, it is more potent than the walnut and purple rice plant drink. Additionally, its relative abundance of olefins, ketones, and alcohols enhances its unique flavor profile, surpassing both other options. Based on sensory analysis, it can be deduced that walnut and purple rice fermented plant drink has the highest overall acceptance rate.

Characterization and application in yogurt of genipin-crosslinked chitosan microcapsules encapsulating with Lactiplantibacillus plantarum DMDL 9010

Microcapsules could improve the protection of probiotics in the lyophilization and gastrointestinal digestion process. The purpose of this study was to prepare Lactiplantibacillus plantarum DMDL 9010 (LP9010) microcapsules by cross-linking chitosan with genipin and to determine the encapsulation efficiency, morphological characterization, storage stability and the application of the microcapsules in fermentation. The results showed that the LP9010 microcapsules embedded in 1.00 wt% genipin cross-linked chitosan were in a uniform spherical shape with a smooth surface and satisfying agglomeration. The LP9010 microcapsules demonstrated the reasonable thermal stability and persistence of biological activity in the range of -20 °C to 25 °C. Additionally, yogurt obtained from the ST + LB + ELP9010 strain formulation with the addition of microencapsulated LP9010 had smaller particles, better taste, and better stability compared with the yogurt obtained from other strain formulations. As detected by GC-MS, the yogurt formulated with ST + LB + ELP9010 as a strain retained more flavor substances and the content of flavor substances was greater than that of the yogurt obtained from other strain formulations. Therefore, genipin cross-link chitosan could be a suitable microencapsulated material for producing yogurt fermentation strains.

Starches modification with rose polyphenols under multi-frequency power ultrasonic fields: Effect on physicochemical properties and digestion behavior

As the main source of energy for human beings, starch is widely present in people's daily diet. However, due to its high content of rapidly digestive starch, it can cause a rapid increase in blood glucose after consumption, which is harmful to the human body. In the current study, the complexes made from edible rose polyphenols (ERPs) and three starches (corn, potato and pea) with different typical crystalline were prepared separately by multi-frequency power ultrasound (MFPU). The MFPU includes single-frequency modes of 40, 60 kHz and dual-frequency of 40 and 60 kHz in sequential and simultaneous mode. The results of the amount of complexes showed that ultrasound could promote the formation of polyphenol-starch complexes for all the three starches and the amount of ERPs in complexes depended on the ultrasonic parameters including treatment power, time and frequency. Infrared spectroscopy and X-ray diffraction indicated that ERPs with or without ultrasound could interact with the three starches through non-covalent bonds to form non-V-type complexes. Scanning electron microscopy showed that the shape of starches changed obviously from round/oval to angular and the surface of the starches were no longer smooth and appeared obvious pits, indicating that the ultrasonic field destroyed the structure of starches. In addition, compared to the control group, the in vitro digestibility study with 40/60 kHz sonication revealed that ultrasonic treatment greatly improved the digestive properties of the polyphenol-starch complexes by significantly increasing the content of resistant starch (20.31%, 17.27% and 14.98%) in the three starches. Furthermore, the viscosity properties of the three starches were all decreased after ERPs addition and the effect was enhanced by ultrasound both for single- and dual-frequency. In conclusion, ultrasound can be used as an effective method for preparing ERPs-starch complexes to develop high value-added products and low glycemic index (GI) foods.

The effect of high-temperature heat treatment and homogenization on the microstructure of set yogurt curd networks

Set yogurt's physical characteristics are greatly affected by the homogenization and heat treatment processes. In our previous study, set yogurt treated at 130°C and with the fat particle size reduced to ≤0.6 μm had equivalent curd strength, less syneresis and smoother texture than yogurt treated at 95°C. When investigating the mechanisms underlying yogurt's physical properties, it is important to evaluate the yogurt's microstructure. We conducted electron microscopy evaluations to investigate the mechanisms of changes in yogurt's physical properties caused by 130°C heat treatment and by a reduction in the fat globule size. We prepared yogurt mixtures by combining heat treatment at 95 and 130°C and homogenization pressure at 10 + 5 and 35 + 5 MPa and then fermented the mixtures in a common yogurt starter. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the structural observations. Fine particles were observed on the surface of the casein micelles of the yogurt treated at 95°C, and the coalescence density between micelles was high. The surface of the yogurt treated at 130°C had few fine particles, and the coalescence density between micelles was low. The yogurt treated at 130°C with 35 + 5 MPa homogenization had low coalescence density between casein micelles, but smaller-particle-size fat globules increased the network density. Approximately 30% of the fat globules were estimated to be incorporated into the yogurt networks compared to the volume of casein micelles. We speculate that 130°C heat treatment alters the structure of whey protein on the surface of casein micelles and interferes with network formation, but reducing the size of fat globules reinforces the network as a pseudoprotein.

Effect of retrograded starch with different amylose content on the rheological properties of stored yogurt

Resistant starch (RS) promotes health benefits; however, when added to foods, it could change the rheological properties. The effect of adding different concentrations (2.5, 5, 7.5, and 10%) of retrograded corn starch with 27% (RNS) or 70% (RHS) amylose content on the properties of yogurt was evaluated through measurements of flow behavior and gel structure. Syneresis and resistant starch content were also assessed. Results were analyzed using multiple regression to describe the effect of starch concentration and storage time on the properties of yogurt added with RNS or RHS. Syneresis was reduced, RNS reinforced the structure increasing the water absorption capacity and the consistency index; meanwhile, RHS provided a yogurt containing up to 10 g of RS in 100 g of sample, allowing obtaining a functional dairy product. Creep-recovery test showed that adding RNS or RHS favored the matrix conformation, and the yogurt samples were able to recover. The final product behaved like a solid material with a firmer and more stable gel structure, resulting in a strengthened gel without weakening the yogurt structure, showing a characteristic like Greek-style or stirred yogurt depending on the type and concentration of retrograded starch.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05735-x.

Effect of adding high concentrations of retrograded starch with different amylose content on the physicochemical properties and sensory attributes of Greek-style yogurt

It is well known that using retrograded starches confers many technological advantages, as well as health benefits when consumed in adequate doses; however, these properties are closely related to the type of starch and/or the treatment applied, therefore, it is of interest to add retrograded starch to popular products such as Greek yogurt. The aim of this work was to investigate the effect of adding two types of retrograded corn starch with different amylose content to a non-strained type of Greek-style yogurt. Retrograded starch from starch containing 27 % (RNS) or 70 % (RHS) amylose was added to yogurt at 0, 10, 12.5, or 15 g/100 g before storage at 4 °C for 14 d. The resistant starch (RS) content, pH, syneresis, flow behavior index, and consistency index, were measured every week. A sensory test was carried out in yogurt added with 12.5 g/100 g of retrograded starches to evaluate acceptability. Adding retrograded starch significantly reduced syneresis while increasing the consistency, firmness, and resistant starch content of the yogurt. No significant differences in general acceptance were observed in samples added with RNS when compared to control. Although a significant difference was observed after adding RHS, the acceptance of the product is still convenient. Adding a high concentration of retrograded starch could help to ensure doses enough for a prebiotic effect of RS with concentrations of 1.74 ± 0.37 to 2.32 ± 0.09 g/100 g and from 3.5 ± 0.08 to 4.21 ± 0.08 g/100 g when RNS or RHS is added while maintaining the quality characteristics of Greek-style yogurt during storage without compromising the acceptability.

Tremella fuciformis polysaccharides as a fat substitute on the rheological, texture and sensory attributes of low-fat yogurt

The potential of Tremella fuciformis polysaccharides (TFPS) as a fat substitute in low-fat yogurt was evaluated in this study. The effects of adding different concentrations of TFPS solution on the physical and chemical properties, texture, rheology, microstructure and sensory properties of low-fat yogurt were evaluated. Compared with control, the addition of TFPS not only increased the solid content and water holding capacity of yogurt, but also reduced syneresis losses in low-fat yogurt. In fact, the addition of TFPS did not affect the color of yogurt but had a positive effect on the texture and sensory of yogurt. In terms of rheology, all low-yogurt samples exhibited rheological to the weak gel-like structures (G' > G″), and the storage modulus and loss modulus of the yogurt added with TFPS were higher than those of the low-fat yogurt control group. Compared with the low-fat yogurt control group, yogurt added TFPS makes the cross-linking of polysaccharides and casein more compact. In conclusion, TFPS has potential as a fat substitute in dairy products.

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TFPS with Medicine Food Homology can be used as a fat substitute for low-fat yogurt.

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TFPS significantly improved the physical and chemical properties of low-fat yogurt.

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0.025% TFPS in low-fat yoghurt was most acceptable in the sensory score.

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Polysaccharide-protein interactions enhanced protein network structure.

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TFPS improved overall organoleptic quality of low-fat yogurt.