Gelatinization Characteristics Research Articles

A global set of barley varieties shows a high diversity in starch structural properties and related gelatinisation characteristics

The gelatinisation temperature and bimodal granule size distribution of barley starch are important characteristics regarding resource efficiency and product quality in the brewing industry. In this work, the diversity in starch amylose content and granule proportions in a set of modern barley varieties (N = 23) was investigated and correlated with their starch gelatinisation behaviour. Milled barley samples had peak starch gelatinisation temperatures ranging from 60.1 to 66.5 °C. Upon separating the barley starch from the non-starch compounds, sample-dependent decreases in starch gelatinisation temperatures were observed, indicating the importance of differences in barley composition. The peak gelatinisation temperatures of milled barley and isolated barley starches were strongly correlated (r = 0.96), indicating that the behaviour of the starch population is strongly reflected in the measurements performed on milled barley. Therefore, we investigated whether amylose content or starch granule size distribution could predict the gelatinisation behaviour of the starches. Broad ranges in the small starch granule volumes (13.9–32.0 v/v%) and amylose contents (18.2–30.7 w/w%) of the barley starches were observed. For the barley samples collected in the north of the USA (N = 8), the small starch granule volumes correlated positively with the peak gelatinisation temperatures of barley starches (r = 0.90, p < 0.01). The considerable variation in starch properties described in this work highlights that, besides starch content, starch gelatinisation temperature or granule size distribution might provide brewers with useful information to optimise resource efficiency.

Effects of Grinding Methods of Tartary Buckwheat Leaf Powder on the Characteristics and Micromorphology of Wheat Dough.

The functional components in tartary buckwheat leaf powder can give flour products higher nutritional value. To comprehensively realize the high-value utilization of tartary buckwheat and its by-products, electric stone mill powder (EMP), ultra-fine mill powder (UMP), steel mill powder (SMP), and grain mill powder (GMP) from tartary buckwheat leaves were used in the preparation of wheat dough, and this was used to explore their effects on dough properties and protein microstructure. With an increase in tartary buckwheat leaf powder, the hydration characteristics, protein weakening rate, and starch gelatinization characteristics of the dough changed, and the water holding capacity and swelling capacity decreased. The retrogradation value increased, which could prolong the shelf life of related products. The water solubility of the dough showed an upward trend and was the lowest at 10% UMP. The addition of UMP produced a more uniform dough stability time and the lowest degree of protein weakening, which made the dough more resistant to kneading. An increasing amount of tartary buckwheat leaf powder augmented the free sulfhydryl content of the dough and decreased the disulfide bond content. The disulfide bond content of the dough containing UMP was higher than that of the other doughs, and the stability of the dough was better. The peaks of the infrared spectrum of the dough changed after adding 10% UMP and 20% EMP. The content of α-helical structures was the highest at 10% UMP, and the content of ordered structures was enhanced. The polymerization of low molecular weight proteins to form macromolecular polymers led to a reduction in surface hydrophobic regions and the aggregation of hydrophobic groups. The SEM results also demonstrated that at 10% tartary buckwheat leaf powder, the addition of UMP was significantly different from that of the other three leaf powders, and at 20%, the addition of EMP substantially altered the structure of the dough proteins. Considering the effects of different milling methods and different added amounts of tartary buckwheat leaf powder on various characteristics of dough, 10% UMP is the most suitable amount to add to the dough.

Effects of stir-frying on the processing characteristics and in vitro digestion of oat flour during storage

This study focused on stir-frying, a traditional Chinese method for treating oats before milling. The effects of stir-frying on the processing properties and in vitro digestion of oat flour during storage have not been explored. The results revealed that stir-frying treatment caused a greater amylopectin content of the oat flour, which made the oat flour easier to improve water absorption and expansion ability. The WAI of stir-fried oat flour was notably greater than that of raw oat flour, while the results of WSI were opposite. The enthalpy of gelatinization of the two oat flours increased significantly (p < 0.05) during storage, and the gelatinization characteristics changed significantly after 9 months of storage. SEM and CLSM studies showed that the dough made from stir-fried oat flour exhibited a well-formed gel network structure, better clumping performance and fat stability during storage. Compared with raw oat flour, stir-fried oat flour had a faster starch hydrolysis rate, a greater rapidly digestible starch (RDS) content, and a lower resistant starch (RS) content. The effect of storage time on the digestibility of stir-fried oat flour was less compared with raw oat flour. Overall, stir-frying improved the processing adaptability, digestibility, and stability of oat flour during storage.

Ultrasound Effect on the Hydrogen Peroxide Oxidation of Corn Starch, Molecular Structure, and Functional Properties of Obtained Starch Derivatives

AbstractThis study aims to determine the effect of ultrasound on the oxidation process of starch, molecular structure, and its functional properties. Corn starch is oxidized by hydrogen peroxide (with Cu(II) or Fe(II) ions as catalysts) in the ultrasound field. Changes in starch structure are identified based on determinations of the carboxyl, carbonyl groups, copper, iron content, molecular characterization by GPC, crystallinity, gelatinization characteristics, and surface area. Functional properties are determined based on analysis of color parameters, water binding capacity, solubility in water, and pasting characteristics. It is found that the effectiveness of the starch oxidation under ultrasound is affected by the presence and type of catalysts. The content of metal incorporated into starch during oxidation is approximately 15% lower when an ultrasound treatment is applied. When starch oxidation is assisted with ultrasound, the metal incorporation preferentially occurs in the pores and holes of the grain. Starches oxidized in the presence of Fe(II) and Cu(II) catalysts can be successfully used not only as thickeners in food industry but also as metal carriers in many industries.

Influences of magnesium ions in water on gelatinization characteristics of starch and its flocculation behaviors on particles

It is inevitable for the occurrence or built-ups of disturbing cations, especially Ca&lt;sup&gt;2+&lt;/sup&gt; or Mg&lt;sup&gt;2+&lt;/sup&gt; ions, in process water during the flotation of iron oxides by using starch as flocculants. In addition to alkali concentrations and temperature, water quality could have an essential role in changing the physicochemical properties of the starch solution and consequently disturbing its flocculation performance on particles. This study aims to identify the effects of magnesium ions on the gelatinization characteristics of starch and its flocculation properties on particles through a series of tests, such as flotation tests, settling tests, size analyses, zeta potentials, powder contact angle, Fourier Transform Infra-Red (FTIR) and X-ray Photoelectron Spectroscopy (XPS) measurement. All results show that magnesium ions at ≤ 4 mmol/L have a positive role due to enlarging the sizes of the particle flocs and accelerating their settling rates. The occurrence of Mg&lt;sup&gt;2+&lt;/sup&gt; ions at higher concentrations during starch gelatinization only obtains a starch sol-gel with entangled configurations and preoccupied active sites, resulting in the slower settling rate of the particle flocs and less hydrophilicity on mineral surfaces. It could be attributed to the cross-link interactions of magnesium-based precipitates with the acidic groups, especially carboxyl groups on the starch remnants. The suitable acid/base interactions between Mg(OH)&lt;sub&gt;2&lt;/sub&gt;/MgCO&lt;sub&gt;3&lt;/sub&gt; compounds with these groups in the starch suspension could be beneficial for enhancing the flocculation of hematite as they could build bridges among the pieces and enlarge their sizes as a “load carrier” for aggregation with minerals. However, too much cross-linking could re-entangle the remnants, block their adsorption sites on mineral surfaces, and eventually, weaken the flocculation capacity of starch.

Making Gelatin From Milkfish Bones (Chanos Chanos) and it Application in Soy Milk Pudding (Glycine Max)

Indonesia's dependence on imported gelatin is increasing. Based on the literature that as much 80% of imported gelatin uses non-halal raw materials in the form of pig skin, it is necessary to make innovations to produce gelatin from halal materials. The purpose of this study was to analyze the characteristics of gelatin from milkfish bones and produce soy milk pudding with characteristics that are acceptable to panelists. The research method consisted of making two types of gelatin using 3% acetic acid solution and 4% hydrochloric acid solution, then conducting physical analysis for gelatin and organoleptic, protein, and syneresis tests for soy milk pudding. The results showed that milkfish bone gelatin using 3% acetic acid solution had a gel strength of 181.5 g/bloom, a yield of 2.2%, and a pH of 7. Meanwhile, milkfish bone gelatin using 4% hydrochloric acid solution had a gel strength of 57.5 g/bloom, a yield of 13.97%, and a pH of 6. Then, the best results were obtained in soy milk pudding with the addition of milkfish bone gelatin in 3% acetic acid solution. In addition, milkfish bone gelatin using 3% acetic acid solution has almost the same structure as commercial gelatin based on FTIR results.

Selected Physicochemical, Thermal, and Rheological Properties of Barley Starch Depending on the Type of Soil and Fertilization with Ash from Biomass Combustion.

The following study analyzed the impact of fertilizing barley with fly ash from biomass combustion grown on two types of soil, Haplic Luvisol (HL) and Gleyic Chernozem (GC), on the properties of starch. The experiment was conducted in 2019 (A) and 2020 (B), and barley was fertilized with ash doses (D1-D6) differing in mineral content. In the tested barley starch samples, the amylose content, the clarity of the paste, and the content of selected minerals were determined. The thermodynamic characteristics of gelatinization and retrogradation were determined using the DSC method. Pasting characteristics, flow curves, and viscoelastic properties of starch pastes were performed. Starches differed in amylose content and paste clarity. The highest gelatinization and retrogradation enthalpy (ΔHG and ΔHR) values were recorded for samples GCD1A and HLD5B. None of the tested factors significantly affected the pasting temperature (PT), but they had a significant impact on the remaining parameters of the pasting characteristics. The average PT value of barley starches was 90.9 °C. However, GCD2A starch had the highest maximum viscosity and the highest rheological stability during heating. GCD2A paste was characterized by the highest apparent viscosity. It was shown that all pastes showed non-Newtonian flow and shear-thinning and had a predominance of elastic features over viscous ones. The resulting gels had the characteristics of weak gels. Ash from burning wood biomass is an innovative alternative to mineral fertilizers. It was shown that the use of such soil fertilization influenced the properties of barley starch.

Development in gelatin-matrix composite films: The incorporation of vitamin C adducts enhances the optical behaviors of gelatin films†

The chemical cross-linking method continues to be widely recognized as the most efficient and popular strategy for modifying gelatin. However, the exploration of enhancing the optical and electrical characteristics of gelatins through the use of organic molecules is still in its early stages. In this investigation, two stable dopants of ascorbic acid adducts were synthesized via the smooth and facile procedure, and their identities were validated through Fourier transform-infrared (FT-IR) and nuclear magnetic resonance spectroscopy techniques, including FT-1H NMR, and FT-13C NMR. The novel gelatin-matrix composite films were fabricated by blending vitamin C adducts with various gelatins including pork gelatin (PG), fish gelatin (FG), bovine gelatin (BG), and chicken gelatin (CG) using the casting method. The chemical and homogenous interactions between dopants and gelatin matrixes were verified through several spectroscopic techniques. The XRD spectra of the composite films show a significant elevation in their amorphous structures when compared to the pure gelatin host. The FT-IR spectra of both the gelatin matrix and their composites demonstrate strong chemical interactions among the functional groups within the gelatin composite films. The UV–vis spectra provided the primary optical information for the synthesized hybrid film. Remarkably, the index of refraction (n) and dielectric loss (ɛi) magnitudes are raised, while the average optical band gap energy (Eg) decreased from 4.9 (pure gelatin) to 3.4 eV. By applying Tauc's model, we successfully recognized the direct electronic transition occurring between the valence band (VB) and the conduction band (CB). The results of our research highlights that minor changes in the adduct composition significantly impact optical and textural properties in polymer composites, offering a plethora of potential technological opportunities. These applications include materials packaging, blocking of harmful light, and encapsulation purposes.

Effect of enzymatically produced tuna oil acylglycerol on the characteristics of gelatin O/W emulsion during microencapsulation using complex coacervation

Complex coacervation is an effective process to deliver ingredients for functional food applications. A stable oil-in-water (O/W) emulsion with desired characteristics significantly affects the complex coacervation and the quality of final microcapsules. In this study, tuna oil was partially hydrolyzed using TL100 and ADL lipases to produce acylglycerols TL100-AC and ADL-AC, respectively. These lipids were subsequently stabilized by gelatin in the O/W emulsion, followed by the complex coacervation with sodium hexametaphosphate. The effect of lipids on emulsion properties, such as interfacial properties, rheological properties, protein conformation and microcapsule formation during complex coacervation, was investigated. Compared with tuna oil-based emulsion, acylglycerol-based ones exhibited reduced droplet size (<600 nm), zeta-potential, interfacial tension (<8 mN/m) and interfacial protein concentration (about 80%). The gelatin in the acylglycerol-based emulsions had reduced β-sheet and slightly increased random coil contents. Compared with the one containing tuna oil, the ones containing acylglycerol possessed higher complex coacervation yields (>75%). These changes were beneficial to the formation of coagulant and flocculant so that gelatin-stabilized acylglycerol-based O/W emulsion resulted in improved complex coacervation between gelatin and sodium hexametaphosphate. This study provides a scientific basis for designing specific gelatin O/W emulsions and microencapsulation for the stabilization and delivery of omega-3 fatty acids.

Influence of Hazelnut and Walnut Oil Cakes Powder on Thermal and Rheological Properties of Wheat Flour.

The aim of the study was to assess the influence of the addition of powdery hazelnut oil cakes (HOC) or walnut oil cakes (WOC) to wheat flour (WF) on its selected thermal and rheological properties. In the research material, part of the wheat flour (5%, 10%, 15%) was substituted with powdery oil cakes based on hazelnuts and walnuts. The control sample was wheat flour (100% WF). In the tested systems with the addition of hazelnut oil cakes (WFHOC) and walnuts (WFWOC), the characteristics of the gelatinization and retrogradation processes were determined using the DSC method, the gelatinization characteristics of 10% pastes using the RVA method, flow curves and viscosity curves, as well as mechanical spectra. Based on the results obtained, it was found that the type of oil cakes and the level of their addition significantly influenced the thermal and rheological properties of the tested systems. Partial replacement of wheat flour with HOC or WOC significantly influenced most DSC parameters. The highest values of gelatinization enthalpy ∆HG and retrogradation ∆HR were characteristic of the WFWOC5% sample (5.9 J/g) and the control sample (1.3 J/g), respectively. All tested systems showed the properties of shear-thinning non-Newtonian fluids, and the partial replacement of wheat flour with HOC or WOC resulted in a significant reduction in the maximum viscosity of pastes, increasing with the increase in the proportion of oil cakes. WFHOC-based pastes were characterized by higher values of the G' and G″ modulus, while their values and the values of the K' and K″ parameters decreased as the share of oil cakes increased. Gels based on all tested systems showed the nature of weak gels (tan δ = G″/G' > 0.1). Replacing part of the wheat flour with nut oil cakes modified the thermal and rheological properties of pastes and gels, and the observed changes were influenced by both the origin and the level of addition of powdered oil cakes. It was found that WFHOC/WFWOC15% systems had reduced viscosity and weakened viscoelastic properties compared to systems with a lower OC content, which is not a favorable feature from the technological point of view. However, these systems were the most stable, which is an advantageous feature. However, for baking purposes, research should be carried out on the rheological properties of dough made from these mixtures.

Improving gelling properties of fish gelatin by γ‐polyglutamic acid with four different molecular weights

SummaryThis work investigated gelling properties and structural characteristics of fish gelatin (FG) modified by four different molecular weights of γ‐polyglutamic acid (γ‐PGA) with 700, 1000, 2000 and 3000 kDa, respectively. Gelation‐melting transition temperature and gel strength increased with the increase of molecular weight in γ‐PGA. Especially, γ‐PGA in 3000 kDa made gel strength, gelation and melting temperatures reaching to 628.08 g (P &lt; 0.05), 22.30 °C and 30.17 °C (P &lt; 0.05), respectively. Non‐covalent interactions existed in FG and γ‐PGA. Such as, new hydrogen bonds were generated between them. Moreover, γ‐PGA with increased molecular weight enhanced three‐stranded helical structure and microscopic meshwork of FG. Finally, a schematic model was described to illustrate the interaction between FG and γ‐PGA in different molecular weights. On the whole, γ‐PGA with high molecular weight significantly improved gelling properties of FG, and could be a potential modifier of FG in the future.

Characterization of the thermal behavior and structural properties of a commercial high-solids confectionary gel made with gelatin

Gelatin plays a critical role in controlling the stability and texture of high-solids gels (HSGs), widely used in confectionery products and nutrient delivery systems. Most gelatin studies have been done on dilute solutions and films, rather than HSGs. Thus, the objectives of this study were to determine the: 1) thermal and structural characteristics of gelatin in a high-solids confectionary gel, 2) effect of renaturation temperature on reformation of gelatin helical structure, and 3) effect of time on loss and reformation of gelatin helical structure. Gelatin HSGs thermal and structural characteristics were investigated using differential scanning calorimetry (DSC), powder x-ray diffraction, and powder x-ray diffraction with total scattering pair distribution function analysis, respectively. The gelatin HSG DSC thermogram exhibited two thermal events: a glass transition and an endothermic peak associated with the helix-coil transition. Based on these results, the helix-coil transition was identified as a thermal denaturation event, not a melting event. The effect of renaturation temperature on gelatin reformation and the effect of time on the loss and reformation of triple-helix gelatin structure were determined using isothermal-DSC. Onset and peak denaturation temperatures increased with renaturation temperature, whereas the amount of triple-helix structure reformed increased with renaturation temperature up to 22 °C, then decreased. Both loss and renaturation of triple-helix structure were time-dependent processes. These results support the development of gelatin HSGs with controlled thermal stability and textural properties and contribute to solving the technical challenges associated with replacing gelatin in HSGs through enhanced understanding, obtained herein, of gelatin's thermal and structural characteristics.

Antioxidant Activity of Acid Pretreated Gelatin Extracted from Duck Skin By-Products

In this study, we have characterized the acid-pretreated gelatin extracted from duck skin by-products. To this end, we employed two-dimensional gel electrophoresis to validate the size of gelatin (72 kDa) and scanning electron microscopy to examine the surface characteristics of gelatin. We next examined the antioxidant activity of acid-pretreated gelatin extracted from duck skin by three-dimensional imaging using electronic spin resonance. The results show Alkyl, 1,1-diphenyl-2-picrylhydrazyl, and hydroxyl radical scavenging capabilities of acid-pretreated gelatin. We hope that these data will help expand the industrial application of duck-skin-derived gelatin.

Effects of glutathione on structural and digestibility properties of high-hydrostatic-pressure-gelatinized maize starch with different amylose/amylopectin ratios

The effect of glutathione (GSH) on the digestibility, physicochemical, and structural properties of maize starch under 600 MPa for 20 min of high hydrostatic pressure (HHP) treatment was determined by in vitro digestion, differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), particle size distribution analysis, Fourier transforms infrared spectroscopy (FT-IR), and Laser Confocal Raman (LC-Raman) microscopy. The findings indicate that the waxy maize starch (WMS) underwent complete gelatinization, whereas the high amylose starches had partial gelatinization. GSH induced a significant increase (p ≤ 0.05) in the slowly digestible starch (SDS) content and a decrease in the rapidly digestible starch (RDS) after HHP treatment. Thermal analysis revealed that GSH increased starch gelatinization temperature. The gelatinization characteristics showed that GSH inhibited starch retrogradation but did not contribute much to starch crystallinity. FT-IR and LC-Raman analyses confirmed the interaction of GSH with starch molecules. The present result emphasizes the impact of GSH on the modelling of starch digestibility and structure properties and inspires the development of new functional foods prepared with HHP.

The differences in metabolites, starch structure, and physicochemical properties of rice were related to the decrease in taste quality under high nitrogen fertilizer application

Nitrogen fertilizer application is one of the key cultivation practices to improve rice yields. However, the application of high nitrogen fertilizers often leads to a reduction in the stickiness of the rice after cooking, thus reducing the taste quality of rice. Moreover, there are differences in taste quality among rice varieties, and the mechanism has not been studied in depth. In this study, two rice varieties (Meixiangzhan2hao and Exiang2hao) were planted under two nitrogen fertilizer levels. The physicochemical properties and taste quality of the rice were determined after maturity. Our results showed that high nitrogen fertilizer level alters tryptophan metabolism in rice, increasing most amino acid content and protein content in rice. The high content of protein and the higher short-range ordered structure of starch inhibited the gelatinization characteristics of starch and reduced the taste quality of rice. Under high nitrogen fertilizer application, Exiang2hao showed smaller increases in protein content, lower level of amylose and relative crystallinity, and higher content of lipid metabolites. These differences in chemical substances resulted in a less pronounced reduction in the taste quality of Exiang2hao. In this study, the taste quality of different rice varieties under different levels of nitrogen fertilizer application was analyzed, providing new ideas for future improvement of rice taste quality.

Effect of hydrophilic and hydrophobic emulsifiers on physio-chemical, structural and water distribution properties of meat-based cookies

Meat-based products are highly susceptible to weak gel formation upon heating. In this study, the effect of different emulsifiers on the rheological, pasting and microstructural properties of meat-based sugar-snap cookies was investigated. Cookies were processed with the addition of freeze-dried fish meat (1% w/w) and emulsifiers (0.5% w/w of wheat flour). The addition of emulsifiers especially diacetyl tartaric acid ester of mono- and diglycerides (DATEM) increased storage modulus (G′), a viscous behavior, compared to control and other emulsifiers. Expansion and hardness were significantly (P < 0.05) improved in DATEM and sodium pyrophosphate (SPP) samples compared to the control indicating the compact structure of starch-protein and emulsifiers molecules. The gelatinization characteristics particularly peak and final viscosities were significantly (P < 0.05) increased in DATEM samples with high water holding capacity (WHC) suggesting the strong interaction among starch-protein and emulsifiers. Low-field magnetic resonance (LF-NMR) analysis exhibited that T21 relaxation time, an indication of tightly bound water, was also highest in DATEM sample while unbound water (T23) was highest in control and sodium dodecyl sulphate (SDS) samples. Scanning electron microscopy (SEM) analysis revealed that DATEM containing samples were dense and uniform whereas wide holes were found in control and SDS samples. It was concluded that DATEM could be an effective emulsifier with improved physio-chemical, structural and pasting properties of meat-based cookies. The study will open a new window for the best use of suitable emulsifiers for meat-based cookies, however, future studies are needed to check their storage stability.

Characteristics of gelatin from lizardfish (Saurida micropectoralis) and threadfin bream (Nemipterus hexodon) skins as influenced by extraction conditions.

Characteristics of gelatin from lizardfish (Saurida micropectoralis) and threadfin bream (Nemipterus hexodon) skins as influenced by extraction conditions.

The Effect of Ultrasonication Time on Gelatin Characteristics of Cobia Fish (Rachycentron canadum) Skin

Cobia skin is still rarely used as a raw material for gelatin production, even though this fish contains a certain amount of collagen which can be a promising source of gelatin. Ultrasound can be used as an alternative to assist the gelatin extraction process when applied with an appropriate time duration. The purpose of this study was to determine the effect of ultrasonication time on the gelatin characteristics of the cobia skin and determine the best ultrasonication time treatment based on its gel strength and viscosity. The research method used was an experimental laboratories with a Complete Randomized Design (CRD) pattern with ultrasound time of 20 minutes, 40 minutes, and 60 minutes and control treatment. The data were analyzed using ANOVA and further analysis of Honestly Significant Differences (HSD) was carried out to determine the differences in treatment. Each treatment was repeated 3 times. The results showed that the ultrasonication treatment affected all gelatin parameters of cobia skin gelatin. Some parameter values at ultrasonication treatment were lower than control treatments such as protein content, moisture content, ash content, and pH, but the yield, gel strength, and viscosity parameters tend to improve as the ultrasound time increases. The ultrasonication treatment for 40 minutes was the best treatment to produce cobia skin gelatin with the highest gel strength and viscosity of 391.40 bloom and 7.33 cP.

Characteristics of halal gelatin from red snapper (Lutjanus malabaricus) bone and its potency as beta-carotene coating material

Gelatin is a material produced from the partial hydrolysis of collagen sourced from the skin and bones of farm animals such as cows and pigs. Gelatin has been used for coatings because it has high permeability and dissolves in warm conditions, so the matrix cross-links are strong. The red snapper fillet processing industry produces 11.2-15% of waste, such as bone which has not been utilized optimally. The objective of this study was to determine the characterization of red snapper bone gelatin as a source of halal gelatin and measure its ability as a coating material for β-carotene pigment microencapsulation. Results showed the characteristics of red snapper bone gelatin with a yield of 10.71%, water content of 9.63%, protein content of 34.06%, ash content of 7.62%, gelatin fat content of 0.28%, and color intensity (L: 62.6). ; a+: 13.3 and b+: 30). The obtained halal gelatin was applied as a coating material for β-carotene pigment microencapsulation through the foam-mat method. It resulted in encapsulation with a yield of 16.75%, water content 9.25%, total carotenoid content 145.49 mg/g, surface carotenoid content 2.04%, solubility 78%, encapsulation efficiency 98.22%, color intensity (L: 50; a+: 29.9 and b+: 14.6), the particle size of 1004.04 μm and irregular shape.

Influences of Trypsin Pretreatment on the Structures, Composition, and Functional Characteristics of Skin Gelatin of Tilapia, Grass Carp, and Sea Perch.

Fish skin gelatin is an important functional product in the food, cosmetics, and biomedicine industries, and establishing a green and effective fish skin gelatin extraction method is an effective way to obtain high-quality gelatin and improve its production efficiency. In this study, a trypsin method was used to extract the skin gelatin of sea perch, tilapia, and grass carp, and the microstructures of skin gelatin of these three fish species were analyzed, with such functional characteristics as thermal stability, gel strength, and emulsifying properties measured. The study results show that the skin gelatin of sea perch and tilapia obtained through the trypsin method has a relatively big molecular mass, a dense network structure, and a stable trihelix conformation. In addition, the skin gelatin of these three fish species has a relatively high β-turn content in the secondary structure, good gel strength, and water absorption properties. The compositions of the collagen-associated proteins in the skin gelatins of these three fish species extracted with the trypsin method are significantly different from each other, with positive effects of decorin and biglycan on the stability of the network structure of gelatin and a certain damaging effect of metalloendopeptidase on the network structure of gelatin. The skin gelatin of tilapia has high thermal stability and good emulsifying performance. Therefore, this gelatin type has bright application prospects in such fields as food processing, cosmetics, and drug development. In contrast, the skin gelatin of grass carp has poor functional properties. Therefore, there are significant differences among the structures and functions of skin gelatin extracted from different kinds of fish through the trypsin method. This finding has provided a useful reference for the production of customized fish gelatin according to demand.