Influence of seaweed dietary fibre as a potential alternative to phosphates on the quality profiles and flavour attributes of frankfurters.

This study primarily aimed to investigate the influence of seaweed dietary fibre (SDF), as a potential alternative to phosphates, on the quality profiles and flavour attributes of frankfurters. The results revealed that SDF addition can significantly improve the cooking yield and texture characteristics of phosphate-free frankfurters (P < 0.05), and 1.00% SDF proved to be the optimal concentration for replacing phosphates in frankfurters. Moreover, electronic nose and electronic tongue analyses demonstrated that SDF incorporation potentially influences the aroma and taste of phosphate-free frankfurters. Furthermore, volatile compound analysis revealed that SDF addition potentially compensates for the decrease in volatile flavour compound content caused by phosphate deficiency. Generally, our results indicate that SDF can be successfully applied as a potential alternative to phosphates and subsequently improve the quality profiles and flavour attributes of phosphate-free frankfurters. Moreover, they provide valuable theoretical guidance for the processing of phosphate-free emulsified meat products.

Elucidating the mechanisms of ultrasound treatment combined with κ-carrageenan addition enhancing the gelling properties of heat-induced myofibrillar protein gel.

This work investigated the effect of ultrasound (US) treatment synergized with κ-carrageenan (KC) on the gel properties, structural characteristics and microstructures of myofibrillar protein (MP) gel. The results demonstrated that simply adding KC enhanced the gel strength and water holding capacity (WHC) of MP gels. Moreover, the gel strength and WHC of MP gels were increased by 56.67 % and 76.19 % via 20 min US treatment synergized with KC, which was mainly attributed to the changes in sulfhydryl content, surface hydrophobicity, and fluorescence intensity of MP gels. Based on the results of molecular docking and secondary structure, it can be hypothesized that the synergistic effect resulted in the rearrangement of the proteins, which altered the interaction site between MP gels and KC, accompanied by stronger binding. Furthermore, the microstructural results indicated that moderate US treatment (20 min) facilitated the production of a more compact and denser MP gels matrix with uniformly sized and distributed pores. However, excessive US treatment (40 and 50 min) caused the MP gels to form looser and disordered gel structure, which reduced the gel strength and WHC. This study suggested that combining of US and KC was a potential tactic to enhance the gelling properties of heat-induced MP gels.

Evaluating the effect of thermo-reversible and thermo-irreversible curdlan gels on the gelling properties and in vitro digestibility of myofibrillar protein gels under low-salt condition.

The purpose of the present study was to investigate the gelling properties and in vitro digestibility of myofibrillar protein (MP) gels under low-salt condition as mediated by different concentrations of thermo-reversible curdlan gels (TRC) or thermo-irreversible curdlan gels (TIRC). The results showed that the incorporation of TRC or TIRC obviously improved the gel strength and water holding capacity of MP gels (P < 0.05). Those properties were most improved by adding 0.3 % TRC or TIRC with gel strength of 0.18 N or 0.17 N and WHC of 54.85 % or 49.05 %. Meanwhile, both TRC and TIRC promoted the transformation of α-helix into ß-sheet, as well as hydrophobic interactions and disulfide bonds, which are the main forces for the maintenance of the MP gels. The microstructure revealed that the formation of dense and uniform protein network structures can be promoted by the addition of TRC or TIRC. The different modes of interaction between TRC or TIRC and MP resulted in different microstructures of the MP gels. Furthermore, incorporation of TRC or TIRC significantly reduced in vitro protein digestibility, especially for the 0.3 % (w/w) form (P < 0.05). Meanwhile, MP gels had the lowest in vitro protein digestibility after the addition of TRC (66.67 %) compared to the form of TIRC (70.93 %). Therefore, our present study indicated that incorporation form of TRC or TIRC have distinct implications on regulating the gelling properties and in vitro digestibility of MP gels under low-salt condition.

Feasibility of Tenebrio molitor larvae protein to partially replace lean meat in the processing of hybrid frankfurters: Perspectives on quality profiles and in vitro digestibility.

The aim of this study was to investigate the effect of replacing different amounts (5 %, 10 %, 15 %, 20 % and 25 %) of lean meat with Tenebrio molitor larvae protein (TMLP) on the quality profiles of hybrid frankfurters. The results showed that there were no obvious differences in moisture, protein or fat content of all the hybrid frankfurters (P > 0.05), only a higher substitution rate (from 10 % to 25 %) resulted in a higher ash content than the control group (P < 0.05). With the increasing replacement rate (5 %, 10 % and 15 %), the cooking loss of the hybrid frankfurters showed the similar effects as the control group (P > 0.05), whereas the higher replacement rates of 20 % and 25 % obviously decreased the emulsion stability of the hybrid frankfurters. Moreover, with lower substitution rate (5 %, 10 % and 15 %) there were no significant differences in cooking loss between the hybrid frankfurters and the control group (P > 0.05), whereas the higher substitution rates (20 % and 25 %) obviously increased the cooking loss of the hybrid frankfurters (P < 0.05). Meanwhile, as the level of substitution increased, the hybrid frankfurters had higher digestibility, poorer texture than the standard frankfurters, as well as the rheological behaviour of hybrid meat batters (P < 0.05). The results showed that a moderate level (15 %) of TMLP was used to replace lean pork could be potentially and successfully be used to produce hybrid frankfurters.

Combined effect of ultrasound treatment and κ-carrageenan addition on the enhancement of gelling properties and rheological behavior of myofibrillar protein: An underlying mechanisms study.

This work aimed to investigate the combined effect of ultrasound (US) treatment and κ-carrageenan (KC) addition on the gelling properties and rheological behaviors of myofibrillar protein (MP). Without US treatment, the KC incorporation promoted the gel strength and water-holding capacity (WHC) of MP gels. These properties were further improved by 20 min US treatment with gel strength of 98.61 g and WHC of 79.87 %, which was mainly attributed to changes associated with hydrophobic interactions and disulfide bonds and the transformation from α-helix to ß-sheet in MP gels. In addition, US treatment for 20 min effectively resulted in a more homogeneous polymer distribution of the MP-KC mixed system, leading to lower particle size and the largest G' and G″ values of the MP-KC mixed gels. However, longer US treatment times (30, 40 and 50 min) rendered lower gel strength, WHC, storage modulus and loss modulus of MP-KC mixed gels, which was mainly due to the formation of loose and disordered gel structures. Our present results indicated that the application of US to MP for an intermediate treatment time (20 min) combined with KC provides a potential and novel strategy to promote the gel qualities of heat-induced MP gels.

Effects and mechanisms of different κ-carrageenan incorporation forms and ionic strength on the physicochemical and gelling properties of myofibrillar protein.

The present work was aimed to investigate the effects of incorporating κ-carrageenan into myofibrillar protein (MP) as a dry powder (CP) or water suspension (CW) and the ionic strength (0.3 or 0.6 M sodium chloride (NaCl)) on MP physicochemical and gelling properties. The results indicated that incorporation of either CP or CW significantly increased turbidity, surface hydrophobicity, particle size and rheological behaviour of MP. In contrast, the protein solubility and fluorescence intensity of MP decreased when added with each form of κ-carrageenan (P < 0.05). These observed effects improved MP's gelling properties and produced a more compact and homogenous gel network after heating treatment. Moreover, the addition of CW rendered higher gel strength, water holding capacity and intermolecular interactions, such as ionic, hydrogen and disulphide bonds and hydrophobic interactions in MP gel compared with those added with CP, especially for 0.3 M NaCl (P < 0.05). Furthermore, addition of CW significantly decreased the α-helix content of MP gels (P < 0.05), which mainly contributing to the transformation from a random structure to an organised configuration. In addition, a higher NaCl concentration (0.6 M) enhanced the gelling properties of MP gels compared with 0.3 M NaCl concentration in the presence of each form of κ-carrageenan. Therefore, our present study indicated that incorporation form of κ-carrageenan and ionic strength have distinctive effects on regulating physicochemical characteristics and improves gelling properties of MP.

Elucidation of interactions between myofibrillar proteins and κ-carrageenan as mediated by NaCl level: Perspectives on multiple spectroscopy and molecular docking.

The present study was aimed to investigate the intermolecular interaction between myofibrillar proteins (MP) and κ-carrageenan (KC) as mediated by KC concentration (0.1, 0.2, 0.3, and 0.4 %, w/w) and NaCl levels (0.3 and 0.6 M) based on the multiple spectroscopy and molecular docking. The results showed that the incorporation of KC increased the turbidity, zeta-potential, and surface hydrophobicity of MP-KC mixed sols with a dose-dependent manner, as well as significantly decreasing the protein solubility (P < 0.05), which indicated that the interaction between KC and MP promoted the expansion of protein structure and exposed more hydrophobic groups. Fluorescence spectra result revealed that the interaction between MP and KC was a static quenching in the fluorescence quenching process, which affected the aromatic amino acids residue microenvironment of MP. Moreover, the existence of KC decreased the α-helix contents of MP (P < 0.05), contributing to the transformation from random structure to organized configuration of MP. In addition, molecular forces, the molecular docking and thermodynamic parameters indicated that hydrophobic interactions, van der Waals force, and hydrogen bonding were considered as the main interaction forces between MP and KC. Furthermore, 0.6 M NaCl level rendered higher solubility and particle size, as well as lower turbidity and the surface hydrophobicity of MP-KC mixed sols than those with 0.3 M NaCl level (P < 0.05), which promoted the unfolding of MP molecule and subsequently increased the numbers of binding sites between MP and KC, facilitating the intermolecular interactions between MP and KC in mixed sols.

Investigation of the effects and mechanism of incorporation of cross-linked/acetylated tapioca starches on the gel properties and in vitro digestibility of kung-wan.

The effects and mechanism of incorporation of cross-linked tapioca starch (CTS) or acetylated tapioca starch (ATS) on the gel properties and in vitro digestibility of kung-wan (a Chinese-style meatball) were evaluated. The results indicated that incorporation of either CTS or ATS significantly enhanced the gel properties of kung-wan in a dose-dependent manner (P < 0.05), as well as the rheological properties of meat batter. Moreover, hydrogen bonds and electrostatic interaction were the major intermolecular forces in kung-wan when incorporated with CTS or ATS. Meanwhile, CTS and ATS acted as fillers in the meat protein gel matrix, which was further verified by the microstructure of kung-wan. However, CTS produced a more uniform and dense meat protein gel network than ATS, which was mainly due to its limited swelling characteristics. In addition, the incorporation of CTS or ATS significantly increased the in vitro digestibility of protein in kung-wan with increasing level of addition (P < 0.05). However, no significant differences in protein digestibility were detected between the CTS and ATS groups at the same addition level (P > 0.05). Our results provided some critical points for the actual application of modified tapioca starch to promote the quality profiles of kung-wan.

In-Depth Insight into the Mechanism of Incorporation of Abelmoschus manihot Gum on the Enhancement of Gel Properties and In Vitro Digestibility of Frankfurters.

This study aimed to investigate the effects of different concentrations (0.1, 0.2, 0.3, 0.4, and 0.5% w/w) of Abelmoschus manihot gum (AMG) on the gel properties and in vitro digestibility of frankfurters. The results indicated that AMG incorporation significantly enhanced the emulsion stability and texture of frankfurters, as well as the dynamic rheological characteristics of raw meat batter, with the optimal concentration being 0.3% (p < 0.05). Furthermore, hydrogen bonds and disulphide bonds were the main molecular forces of the frankfurters in the presence of AMG. Microstructural images showed that more uniform and dense microstructures of frankfurters were formed due to AMG supplementation. In addition, AMG incorporation significantly increased the in vitro protein digestibility of frankfurters as the level of addition increased (p < 0.05). In conclusion, our results provided critical information for the practical application of AMG in the production of emulsified meat products.

Ultrasound-assisted alkaline extraction of protein from Tenebrio molitor larvae: Extraction kinetics, physiochemical, and functional traits.

Currently, as a promising alternative protein source, the interest of edible insect protein has been continuously increased. However, the extraction processing had distinct effects on the physicochemical properties and functionalities of this novel and sustainable protein. In this study, Tenebrio molitor larvae protein (TMLP) was extracted via ultrasound (US)-assisted alkaline extraction. The changes of extraction kinetics, physicochemical characteristics, and functional properties of TMLP as a function of US time (10, 20, 30, 40, 50 min) were investigated. The results showed that 30 min US treatment rendered the maximum protein yield (60.04 %) (P < 0.05). Meanwhile, Peleg's model was considered a suitable model to represent the extraction kinetics of TMLP, with a correlation coefficient of 0.9942. Moreover, the protein secondary structure, particle size, and amino acid profiles of TMLP were changed under the US-assisted alkaline extraction process. Additionally, a significant improvement of the functional properties of TMLP extracted with this method was observed compared to traditional alkaline extraction. In conclusion, the present work suggests that US-assisted alkaline extraction could be considered as a potential method to improve the protein yield, quality profiles, and functional properties of TMLP.

Mechanisms underlying the effects of ultrasound-assisted alkaline extraction on the structural properties and in vitro digestibility of Tenebrio molitor larvae protein.

Edible insects have been considered as a sustainable and novel protein source to replace animal-derived proteins. The present study aimed to extract Tenebrio molitor larvae proteins (TMP) using ultrasound-assisted alkaline extraction (UAE). Effects of different UAE times (10, 20, 30, 40, and 50 min) on the structural properties and in vitro digestibility of TMP were comparatively investigated with the traditional alkaline extraction method. The results revealed that ultrasonication could effectively alter the secondary/tertiary structures and thermal stability of TMP during UAE. The molecular unfolding and subsequent aggregation of TMP during UAE were mainly attributed to the formation of disulfide bonds and hydrophobic interactions. Moreover, TMP extracted by UAE had higher in vitro digestibility and digestion kinetics than those extracted without ultrasound, and the intermediate UAE time (30 min) was the optimal ultrasound parameter. However, longer UAE times (40 and 50 min) lowered the digestibility of TMP due to severe protein aggregation. The present work provides a potential strategy for the extraction of TMP with higher nutritional values.

Application of seaweed dietary fiber as a potential alternative to phosphates in frankfurters with healthier profiles.

This study was designed to investigate the utilization of seaweed dietary fiber (SDF) as a potential alternative to phosphates on the quality profiles of phosphate-free frankfurters. The results showed that the incorporation of SDF obviously promote the textural parameters of phosphate-free frankfurters, which was effectively verified by scanning electron microscopy. Meanwhile, SDF effectively retarded lipid oxidation of phosphate-free frankfurters during storage (P < 0.05). Moreover, 1.00% SDF was proven to show the best optimal phosphates replacing effect, as well as overcome the quality defects of phosphate-free frankfurters to the maximum extent. In addition, hydrogen bonding and hydrophobic interactions were the primary molecular force in SDF-added phosphate-free frankfurters. Therefore, our results implied that SDF can be considered as a feasible alternative for the processing of phosphate-free frankfurters with improved quality profile and superior health benefits which consistent with the demand of healthier meat products.

Additive Effects of L-Arginine with Potassium Carbonate on the Quality Profile Promotion of Phosphate-Free Frankfurters.

The present study investigated the additive effects of L-Arginine (L-Arg) with potassium carbonate (PC) on the quality characteristics of phosphate-free frankfurters. The results showed that L-Arg combined with PC could act as a viable phosphate replacer by decreasing cooking loss and improving the textural properties of phosphate-free frankfurters (p < 0.05), mainly because of its pH-raising ability. Moreover, L-Arg could assist PC in effectively retarding lipid oxidation in phosphate-free frankfurters during storage (p < 0.05). Furthermore, 0.1% L-Arg combined with 0.15% PC was found to exhibit the best optimal phosphate-replacing effect. This combination could also overcome quality defects and promote the sensory attributes of phosphate-free frankfurters to the maximum extent. Therefore, our results suggest that L-Arg combined with PC can be considered a feasible alternative for the processing of phosphate-free frankfurters with an improved quality profile and superior health benefits.

Micronized cold-pressed hemp seed cake could potentially replace 50% of the phosphates in frankfurters.

Present study aimed to investigate the concentration effect of micronized cold-pressed hemp seed cake (MCPHSC) on the quality profiles and sensorial attributes of 50% phosphates reduced frankfurters. The results showed that MCPHSC could be used as an ideal phosphates replacer for obviously decreasing the cooking loss and promoting textural and gel properties of reduced-phosphates frankfurters (P < 0.05), which was verified by scanning electron microscopy. Moreover, the incorporation of MCPHSC could significantly inhibit the occurrence of lipid oxidation of reduced-phosphates frankfurters during storage in a dose-dependent manner (P < 0.05). Additionally, replacing 50% phosphates with 2% (w/w) MCPHSC was found to possess the best optimal replacement effect to enhance the quality profiles of reduced-phosphates frankfurters (P < 0.05). However, a higher amount of MCPHSC had a negative effect on the sensorial evaluations of the reduced-phosphates frankfurters. Our results suggested that the addition of MCPHSC could be applied as a practical way for improving the quality defects of reduced-phosphates frankfurters.

Effects of ethanol pre-treated whey protein isolates on the physical stability and protein-lipid co-oxidation in oil-in-water emulsions.

The changes of physical stability and protein-lipid co-oxidation of oil-in-water (O/W) emulsions which stabilized by whey protein isolates (WPI) and ethanol pre-treated WPI (EWPI) under different homogenization methods were investigated. Compared with WPI, EWPI could obviously enhance the O/W emulsion's stability due to smaller particle size and higher level of adsorbed proteins. Moreover, protein-lipid co-oxidation was observed in both WPI and EWPI stabilized O/W emulsions and controlled by the characteristics of the adsorbed proteins. EWPI protect themselves from attacked of lipid oxidation products more effectively than WPI, showing lower N'-formyl-l-kynurenine or carbonyl contents and degree of aggregation, as well as higher fluorescence intensity. Furthermore, high-pressure homogenization induced higher levels of adsorbed proteins in O/W emulsions than ultrasound homogenization, resulting in a higher degree of protein oxidation and lower degree of lipid oxidation. Therefore, EWPI can be applied as an efficient emulsifier in emulsion foods with higher physical and oxidative stabilities.

Impact of different ionic strengths on protein-lipid co-oxidation in whey protein isolate-stabilized oil-in-water emulsions.

Protein-lipid co-oxidation of whey protein isolate (WPI)-stabilized oil-in-water (O/W) emulsions with different ionic strengths (0, 100, 200, 300 and 400 mM) during storage were investigated. The results proved that changes in levels of adsorbed proteins induced by different ionic strengths could obviously affect the occurrence of protein-lipid co-oxidation. The level of oxidative stress was higher in adsorbed proteins extracted from control sample than in those extracted from emulsions with 300 or 400 mM ionic strengths. This was indicated by higher levels of N'-formyl-l-kynurenine (NFK) and carbonyl, lower fluorescence intensity and more serious unfolding of protein structure. Moreover, control sample showed the highest oxidative stability, which was indicated by lower levels of primary and secondary lipid oxidation products. These findings clearly illustrated that altered levels of adsorbed proteins induced by different ionic strengths play a crucial role in affecting protein-lipid co-oxidation in O/W emulsions.

Pre-dried mealworm larvae flour could partially replace lean meat in frankfurters: Effect of pre-drying methods and replacement ratios.

This study aimed to investigate the effect of replacing different amounts (5%, 10%, and 15%) of lean meat with yellow mealworm larvae (Tenebrio molitor L.) flour (YMLF) obtained via two different pre-drying methods on the quality profiles of hybrid frankfurters. With the increasing replacement ratio, the cooking loss of the freeze-dried YMLF (FD-YMLF) groups gradually increased, whereas those of the microwave drying YMLF (MD-YMLF) groups were always better than those of the control group (P < 0.05). Moreover, the MD-YMLF group showed superior textural properties than FD-YMLF group under the same replacement ratio (P < 0.05), especially for MD-YMLF-10% group. Additionly, with the increasing replacement ratio, the hybrid frankfurters had lower sensorial scores than standard frankfurters (P < 0.05), whereas the MD-YMLF group was always better than the FD-YMLF group for the same replacement ratio (P < 0.05). Our results indicated that MD-YMLF could be used as a potential lean meat replacement to process emulsified meat products.

Effects of the Incorporation of Calcium Chloride on the Physical and Oxidative Stability of Filled Hydrogel Particles.

In this study, the effects of calcium chloride (CaCl2) addition on the physical and oxidative stabilities of filled hydrogel were investigated. The results revealed that CaCl2 significantly enhanced the particle size, interfacial layer thickness, apparent viscosity, and viscoelastic behavior of filled hydrogels and decreased their light and whiteness values (p < 0.05). This phenomenon was mainly attributed to the strong binding ability between Ca2+ and protein/pectin mixtures, which were present in the interfacial area or aqueous phase, as verified by cryo-scanning electron microscopy results. Moreover, lower levels of CaCl2 (2 or 4 mM) significantly enhanced the oxidative stability of filled hydrogels (p < 0.05), particularly at a concentration of 4 mM. However, a higher level of CaCl2 (6 or 8 mM) resulted in an electrostatic shielding effect, which resulted in the aggregation of multiple droplets and the flocculation of the filled hydrogels, which negatively affected the oxidative stability of filled hydrogels. The findings of this study indicated that appropriate Ca2+ levels (4 mM) improved the physical and oxidative stability of filled hydrogel, and this finding may provide useful insights for the development of effective delivery systems for specific applications.

Reduction of phosphate content in frankfurters by up to 50% using micronized cold-pressed sesame seed cake.

Our study assessed the effects of micronized cold-pressed sesame seed cake (MCPSSC) incorporation as a potential phosphate replacement on the textural and gel properties of 50% reduced-phosphate frankfurters. Our results indicated that moderate MCPSSC addition (4%) resulted in the strongest inhibition of textural quality deficits in reduced-phosphates frankfurters, which was confirmed via scanning electron microscopy. Moreover, although some differences were perceived in the sensorial parameters and flavour profile of reduced-phosphate frankfurters prepared with MCPSSC, all of them were deemed acceptable. Therefore, incorporating moderate amounts of MCPSSC is a feasible strategy to reduce the phosphate contents of frankfurters and promote "clean label" practices.

Effects of Sodium Chloride on the Physical and Oxidative Stability of Filled Hydrogel Particles Fabricated with Phase Separation Behavior.

The objective of this study was to investigate the influence of sodium chloride (NaCl) concentration (0-500 mM) on the physical and oxidative stabilities of filled hydrogel that were stabilized using heat-denatured whey protein concentrate and high methoxy pectin. Our results showed that with an increase in NaCl concentration, the particle sizes, zeta-potentials, and interfacial layer thickness of filled hydrogels significantly increased and the lightness and whiteness gradually decreased (p < 0.05). Moreover, rheological characterization revealed that the apparent viscosity and viscoelastic behavior gradually decreased at higher NaCl concentration, which was mainly ascribed to the influence of NaCl on the electrostatic repulsion between droplets, thereby adversely impacting the physical stability of filled hydrogels. Furthermore, the result of cryo-scanning electron microscopy also verified the abovementioned results. Notably, higher NaCl concentration significantly promoted the oxidation of lipids and proteins (p < 0.05), thereby decreasing the oxidative stabilities of filled hydrogels. Our results indicated that filled hydrogels prepared under different ionic strength conditions can provide the theoretical basis for their future application in emulsion-based foods.