Comparative study on the effects of d-psicose and d-fructose in the Maillard reaction with β-lactoglobulin

d-Psicose, recognized as a noncaloric sweetener, has shown a great potential in food industry. In the present study, d-psicose and d-fructose were used to modify bovine β-lactoglobulin (β-Lg) through Maillard reaction. The Maillard reaction process and the physicochemical and structural properties of the modified proteins were also investigated. The result showed that compared to d-fructose, d-psicose played a more effective role in the Maillard reaction, especially after the initial stage of the reaction. Moreover, the modified β-Lg with d-psicose had more polymeric compounds, higher antioxidant activity, but lower thermal stability than that with d-fructose. These findings, especially the structural changes of the modified proteins, supplied detail information on the Maillard reaction of d-psicose, and could provide some guidance to the practical applications of this rare sugar on food industry.     

A Review on the Fermentation of Foods and the Residues of Pesticides—Biotransformation of Pesticides and Effects on Fermentation and Food Quality

Residues of pesticides in food are influenced by processing such as fermentation. Reviewing the extensive literature showed that in most cases, this step leads to large reductions in original residue levels in the fermented food, with the formation of new pesticide by-products. The behavior of residues in fermentation can be rationalized in terms of the physical-chemical properties of the pesticide and the nature of the process. In addition, the presence of pesticides decrease the growth rate of fermentative microbiota (yeasts and bacterias), which provokes stuck and sluggish fermentations. These changes have in consequence repercussions on several aspects of food sensory quality (physical-chemical properties, polyphenolic content, and aromatic profile) of fermented food. The main aim of this review is to deal with all these topics to propose challenging needs in science-based quality management of pesticides residues in food.     

Effect of ascorbyl palmitate on the preservation of α-tocopherol in sunflower oil,alone and with herbs and spices

Ascorbyl palmitate (AP) (200 ppm) preserved α-tocopherol in sunflower oil at 95°C and delayed the onset of rancidity. Both effects increased with AP concentration (r² = 0.96 and 0.97 respectively) but levelled off near ∼700 ppm. The improved anti-rancidity effect was due to the increased preservation (P<0.01). Synergism was observed for both effects for AP combined with sage, turmeric, oregano and marjoram. Clove and thyme gave a smaller synergistic effect whereas basil inhibited. Neither bay nor cumin had any effect. Both the preservative (PF_p) and anti-rancidity effects (PF_r) were directly related to the thyme concentration (0–2000 ppm). Again, the decreased rancidity was due to the increased preservation (P<0.01). The optimum AP concentration (0–1000 ppm) was around 250 ppm (P<0.01) with thyme present (at 500 ppm) (r²=0.99). The increased delay in rancidity was due to the improved preservation of α-tocopherol (r=1, r² = 0.99, P<0.01). Both the logarithm of the induction time and the preservative effect for the mixture of thyme and AP was directly related to the temperature (80–105°C). The mode of action of AP is also discussed.     

Study on the structure and properties of modified silk with ultraviolet absorbent北大核心CSCD

The silk fiber has an irreplaceable position in textile fibers and related silk fabrics have the advantages of light and airy texture good moisture absorption and breathability comfort in wear etc. It is also widely used in other fields such as the biomedical sector. However silk also has its own limitations poor light resistance and susceptibility to ultraviolet light especially the ultraviolet light of 290-400 nm wavelength in daylight such as under which condition it is prone to yellowing and photodegradation. The yellowing of silk is due to the photo-oxidation of tyrosine and tryptophan in silk protein under the action of ultraviolet light from sunlight and due to the production of yellow substances which affects the whiteness of silk. In addition from the molecular structure of silk most of the amino acids susceptible to UV light are distributed in the amorphous region. As the amorphous region is affected the structure of the crystalline region is also gradually relaxed the local degradation begins and the silk protein macromolecule chain is cleaved which leads to the decrease of the mechanical properties of silk fibers and accelerates the aging of silk fibers and fabrics. Therefore it is necessary to modify the silk products outside the anti-purple line. The current methods used to modify silk are mostly for post finishing modification including coating impregnation and chemical grafting methods but these methods often affect the original color or feel of the fabric and the durability of the modified effect is also poor. The feeding method is a green method to obtain modified silk by spraying mulberry leaves or artificial feed mixed with modifier which is ingested by silkworm and transferred to silk gland. In this study five aminobenzene UV absorbers were used as exogenous additive food for silkworms. The effect of molecular polarity on the transport of modifiers to silk glands was investigated and their effects on silkworm development and silk structural properties were studied. It was found that the aminobenzene UV absorbers were more easily transferred to the central silk gland silk glue and less to the posterior silk gland (fibroin). 4-dimethylaminobenzoic acid was found to be the highest in the posterior silk gland with a content of 3. 27 μg / strip. The cocoon width and cocoon quality of this group were significantly lower than those of the control group and the silk gum content was increased when this group was used as the study object. Compared with the control group the relative content of β-folded structure and crystallinity of the silk in the addition feeding group decreased slightly. The silkworm silk in the feeding group showed a certain UV absorption ability. After 330 h UV irradiation the breaking strength and elongation of the control group decreased by 48. 95% and 43. 52% respectively while those of the feeding group decreased by 42. 03% and 34. 18% respectively. In this paper UV absorbers were added to silkworms to obtain modified silk mainly focusing on the transfer of the modifier to the silk gland and the structural properties of the modified silk only for the most UV absorbers to enter the silk gland of the posterior group of silk. Other properties of the modified silk such as washing resistance have not been studied and some more in-depth studies are required. For instance it needs to be studied in depth for the limited absorption of exogenous additives by silkworms additive food's being not always absorbed by silkworms and transferred to the silk gland and the mechanism of action between the additive food and silk protein after the former's entering the silk gland. © 2022 Authors. All rights reserved.     

Effects of lipid supplementation on the yield and composition of milk from cows with different β-lactoglobulin phenotypes

Responses to lipid supplementation differ between dairy breeds and genetic lines suggesting nutrition by genotype interactions. β-Lactoglobulin phenotype is associated with changes in yield and composition of milk. The response of cows with different β-lactoglobulin phenotypes to lipid supplementation has not been examined. Furthermore, we examined whether lipid supplementation alters milk protein composition. By using a randomized block design, we fed Holstein cows for 3 wk either a control diet containing 2.8% crude fat (n = 19) or an experimental diet that was supplemented with 4.2% tallow (n = 20). Before randomization, all cows were fed the supplemental tallow diet for at least 2 wk. Dry matter intake, body weight, milk yield, and milk composition were measured in the last week before and during the experimental period. Feeding supplemental tallow increased dry matter intake and yields of milk and milk components, including casein content, without decreasing milk component content or altering milk protein composition. On the low-fat control diet, cows with the β-lactoglobulin allele B had a greater milk and milk component yield than cows with the A allele, whereas no differences by β-lactoglobulin phenotype were observed in cows on the tallow supplement diet. Our results suggest that cows that differ in β-lactoglobulin phenotype respond differently to a low-fat diet and that feeding cows 4.2% of additional tallow increases milk yield without affecting milk component content and milk protein composition.     

The effect of dietary supplementation of vitamins C and E on the α-tocopherol content of muscles, liver and kidney, on the stability of lipids, and on certain meat quality parameters of the longissimus dorsi of rabbits

The trial was carried out to investigate the effects of adding to the diet of rabbits vitamin E (40; 300; 500 ppm) and C (0; 500 ppm), on vitamin E deposition in the muscles and organs, on the oxidative stability of muscular lipids, and on various meat quality characteristics. The α-tocopherol content in muscles and organs was roughly doubled by feeding the highest levels of vitamin E; it was also increased by giving 500 ppm of vitamin C, but only in those muscles of rabbits receiving 40 ppm of vitamin E. The α-tocopherol content in tissues was negatively correlated with TBARS values of the longissimus dorsi (LD) at days 6 and 8 post mortem (p.m.). Five hundred parts per million (ppm) of vitamin C increased lipid stability of the LD at both 6 and 8 days p.m., though its effect was significant only with 40 ppm of vitamin E. Moreover, 500 ppm of vitamin C resulted in the lowest L(*) and highest pH values at all p.m. times, when the dietary vitamin E was equal to 40 ppm, and in the highest L(*) and lowest pH values when the vitamin E was equal to 300 ppm. Conversely, weight losses of the LD were the lowest, at days 6 and 8 p.m., in the group fed the highest levels of both vitamins.     

Study of the functionality of selected hydrocolloids and their blends with κ-carrageenan on storage quality of vanilla ice cream

In the present paper, the functionality of hydrocolloids related to the rheological, physical and sensory characteristics of ice cream mixes and frozen ice cream was studied. Carboxylmethylcellulose, guar gum, sodium alginate and xanthan gum were used as primary stabilizing agents, whereas κ-carrageenan as secondary. The hydrocolloid concentrations were 0.1 and 0.2% and the primary to secondary ratio was 9:1. The ice cream samples were stored under quiescent frozen conditions. Samples were taken after 4, 8 and 16 weeks of storage and examined for the functionality of the stabilizing systems.The addition of hydrocolloids significantly reinforced the shear thinning behavior, particularly in the case of sodium alginate, xanthan gum, and κ-carrageenan which was attributed to gelation phenomena. Sodium alginate attained the better stabilizing effect improving textural quality and acceptance of ice creams even after 16 weeks of storage, whereas the presence of κ-carrageenan found to be a crucial factor for the cryoprotection. Xanthan gum was also evaluated as an effective stabilizing agent, indicating that gelling hydrocolloids may remarkably amend ice cream shelf life.Moreover, principal components and cluster analysis of instrumental and sensory data furnished important information for the correlation of objective and sensory properties and discrimination of stabilizing systems based on quality criteria.     

Can the combination of flaxseed and its lignans with soy and its isoflavones reduce the growth stimulatory effect of soy and its isoflavones on established breast cancer?

Consumption of phytoestrogen (PE)-rich foods (i. e., soy and flaxseed (FS)) is increasing because of their suggested health benefits. However, recent studies raise concern over the safety of soy and its isoflavones, particularly genistein (GEN), for postmenopausal breast cancer (BC), due to their potential stimulatory effects on human breast tissue and on the growth of existing tumors in rodents. FS, rich in PE lignans, which is metabolized to the mammalian lignans enterolactone (ENL) and enterodiol (END), has consistently been shown to have tumor inhibitory effects in a human clinical trial as well as rodent BC models. Using the preclinical athymic mouse postmenopausal BC model, combining FS with soy protein or GEN with END and ENL, was found to negate the tumor stimulatory effects of soy protein or GEN alone. The mechanism may be related to the modulation of estrogen receptor and MAPK signaling pathways. If these studies can be confirmed in clinical trials, then consumption of combined soy and FS, or their PEs, may reduce the tumor growth stimulatory effect of soy or GEN. This may indicate that if soy is consumed with lignan-rich foods, it may continue to induce its other beneficial health effects, without inducing adverse effect on postmenopausal BC.     

Effect of ultrasound treatment on the wet heating Maillard reaction between β-conglycinin and maltodextrin and on the emulsifying properties of conjugates

Soy β-conglycinin (7S) was grafted with maltodextrin (MD) by combined ultrasound treatment and wet heating Maillard reaction in this work. The physicochemical and emulsifying properties of 7S–MDH (classical wet heating) and 7S–MDUH (ultrasound-assisted wet heating grafting) have been investigated. Ultrasound treatment could speed up the conjugation process and obtain a protein–polysaccharide conjugate that exhibits superior functionality compared with the one obtained simply by wet heat treatment. The degree of grafting of 32.73 % was obtained in 30 min by ultrasound-assisted wet heating , whereas classical wet heating required 60 min. SDS-PAGE analysis indicated that 7S globulin had become complex with MD to form conjugates of higher molecular weight. Reduction in the contents of lysine and arginine during the graft reaction indicated that these two amino acid residues had the covalent linkage between 7S and MD. The results of secondary structure showed that grafted 7S had decreased α-helix level and increased β-sheet and unordered coil levels. In addition, ultrasound-assisted treatment significantly changes in surface hydrophobicity (H ₀), emulsifying activity index and emulsifying stability index of 7S (p < 0.05). Moreover, the emulsions of 7S–MDUH were stable under unfavorable conditions, such as extreme pH, ionic strength and heat treatment temperature, which is mainly due to changes in surface hydrophobicity (H ₀) and secondary structure, resulting in a reduction in protein molecular steric hindrance in an increase in molecular flexibility. This study demonstrated that combined ultrasound treatment and wet heating Maillard reaction could potentially be applied as a method to prepare 7S–MD conjugates.     

Preparation of and studies on the functional properties and bactericidal activity of the lysozyme–xanthan gum conjugate

The purpose of this research was to produce a xanthan gum–lysozyme conjugate (Lyz–XM) and to investigate the effect of conjugation on functional properties and antimicrobial properties of the conjugated products. The antimicrobial activity of Lyz is limited to Gram positive bacteria, but its antibacterial spectrum can be extended towards Gram negative bacteria by conjugation with carbohydrate through the Maillard reaction. Lyz was allowed to react with XG under mild Maillard reaction condition (pH 8.5 and 60 °C for 10 days) and conjugation was confirmed by SDS-PAGE, enzyme activity and determination of sugar content of the product. Results showed that under optimal conditions approximately 1.9 mmol XG was attached to one mol Lyz. The Lyz–XG conjugate showed higher solubility at acidic pHs and at different temperatures, increased heat stability with improved emulsion and foaming properties. Additionally, Lyz–XG conjugate showed antioxidant properties and significantly inhibited the growth of Staphylococcus aureus and Escherichia coli in a dose dependent manner. These findings may broaden food applications of Lyz as a functional ingredient with high quality emulsifier, foam producer or natural antibacterial agent in food or pharmaceutical industries.     

Effect of temperature and pH on the solubility of caseins: environmental influences on the dissociation of α(S)- and β-casein

Selective precipitation is a common method for the isolation of β-casein, using the different calcium sensitivities of the individual caseins and the selective solubility of β-casein at a low temperature. In previous studies, it has been indicated that the β-casein yield depends on the physicochemical characteristics of the casein raw material used for fractionation. The objective of this study was to evaluate and compare the solubility of α(S)- and β-casein in solutions of micellar casein, sodium caseinate, and calcium caseinate as a function of pH and temperature. Additionally, the solubility of isolated α(S)- and β-casein fractions in demineralized water, ultrafiltration permeate, and a calcium-depleted milk salt solution was investigated depending on the pH and temperature. Furthermore, micellar casein, sodium caseinate, and calcium caseinate were subjected to a calcium chloride-precipitation process to determine the solubility of α(S)- and β-casein in calcium chloride precipitate, which is produced during selective precipitation, as a function of temperature and pH. Generally, the temperature had only a marginal influence on the α(S)-casein solubility compared with the β-casein solubility, whereas the solubility was shown to be strongly influenced by the pH. Our results suggest that the yield of β-casein obtained during isolation by means of selective precipitation may be a result of the solubility characteristics of α(S)- and β-casein in calcium chloride precipitate. Manufacturers may consider a simple solubility experiment before the β-casein isolation process by means of selective precipitation to predict β-casein yield.     

Effect of γ-polyglutamate on the rheological properties and microstructure of tofu

The effects of γ-polyglutamates with different concentrations (0.1%, 0.15%, 0.2%) and molecular weights (high, medium, low) addition on the rheological properties, microstructure, and syneresis of tofu were studied. The addition of γ-polyglutamate increased the gelation time, and decreased the storage modulus (G′) and the loss modulus (G″) of tofu. The molecular weight and concentration of γ-polyglutamate effectively changed the rheological properties of tofu. The network of tofu without γ-polyglutamate addition was constructed by fine strands in a dense arrangement as seen by using scanning electron microscope. However, the addition of γ-polyglutamate reduced the thickness of the strands in tofu network. Tofu syneresis was also reduced by the addition of γ-polyglutamate. Increase the concentration of γ-polyglutamate significantly decreased the syneresis of tofu. This trend was more evident on the tofu with high molecular weight γ-polyglutamate.     

Influence of maltodextrin type and multi-layer formation on the freeze-thaw stability of model beverage emulsions stabilized with β-lactoglobulin

The influences of maltodextrin (MD) addition and multi-layer formation on the freeze-thaw stability of β-lactoglobulin (β-Lg)-stabilized oil-in-water beverage emulsions (0.1 wt% corn oil, 0.006 wt% β-Lg) were investigated. Various beverage emulsions were prepared depending on MD concentration (0–20 wt%), its dextrose equivalent (M150 or M250), and the presence or absence of additional polysaccharides (pectin, alginate, or ι-carrageenan) coatings around the emulsion droplets. All emulsions (β-Lg- and β-Lg-polysaccharide-coated emulsions) were unstable to experimental freeze-thaw cycling in the absence of MD. In the presence of MD, all emulsions containing M250 had better stability to droplet aggregation than those with M150, regardless of MD concentrations and freeze-thawing. The optimum concentrations of M250 required to prevent emulsions destabilization under the freeze-thawing were 6, 15, and 2% for β-Lg-, β-Lg-ι- carrageenan-, and β-Lg-pectin-coated emulsions, respectively. This study implicates practical information to improve freeze-thaw stability of some beverage emulsion products that inevitably go though freezing during processing.     

Effect of thermal and high-pressure processing on the nutritional value and quality attributes of a nectarine purée with industrial origin during the refrigerated storage

The application of hydrostatic high pressure on an industrial line of nectarine (Prunus persica L.) purées was assessed in comparison with the traditional thermal treatment of pasteurization. Changes after thermal processing (85 °C, 5 min) and after high-pressure processing (HPP: 450 or 600 MPa for 5 or 10 min) and during the refrigerated storage (60 d) of an industrially produced nectarine purée were evaluated. Conventional heat pasteurization as well as HPP showed similar microorganisms' inactivation and maintained the microbial stability of purées until the end of the refrigerated storage (60 d). In general, thermally treated purée and HP-treated purée at 600 MPa showed more intense color changes after processing than the other treatment. In addition, thermally treated purée showed more intense color changes during storage than HPP. The highest carotenoids extractability was found in those purées treated at the lowest high-pressure-treatment intensity and holding time (450 MPa/5 min), but at the end of the storage (day 60), no differences in individual or total carotenoid levels were found between the purées. HPP at 600 MPa/10 min showed the highest polyphenols content after the treatment and during the storage. At day 0, significantly higher values were found of total antioxidant activity in purée HP-treated at 450 MPa/10 min than in untreated purée; while at the end of the storage, HP-treated purée at 600 MPa/10 min had the highest antioxidant activity. Hydrostatic high-pressure application in the industrial line of nectarine purée presented some advantages compared to the thermal treatment; however, some of the changes found were lessen during the storage period. In addition, more studies need to be carried out for HP-treatment intensity optimization.     

Extraction and chemical characterization of rye arabinoxylan and the effect of β-glucan on the mechanical and barrier properties of cast arabinoxylan films

Water-extractable hemicellulose (WEH) fractions, containing approximately 65% arabinoxylans (WE-AX) and 20% mixed-linkage β-glucans were isolated from rye bran. In addition, water-extractable mixed-linkage β-glucans (BG) were isolated from oat bran as a reference material. The β-glucan content of the rye hemicellulose isolate was reduced to less than 5% by a selective lichenase treatment. Rye hemicelluloses, WEH and WE-AX had arabinose-to-xylose ratios of 0.54 and 0.57 and weight-average molecular weights (M_w) of 270 000 and 232 000 g/mol respectively. The M_w of BG was higher at 386 000 g/mol. The material properties of films prepared from the rye hemicellulose isolate and WE-AX as such, or with varying amounts of added BG (20:80; 50:50; 80:20 ratios) were studied. Prior removal of β-glucan from the isolate decreased the tensile strength of the films significantly as well as the elongation at break. Addition of BG to the purified WE-AX resulted in an increase in the tensile strength and elongation at break of the films. In contrast, the presence of BG had no clear effect on the oxygen permeability of the films. Both pure rye WE-AX and pure BG films showed excellent oxygen barrier properties (between 0.9 and 1.0 cm³ μm/m² d kPa). However, the water vapor permeability increased with addition of increasing amounts of BG to WE-AX. To our knowledge, this is the first study on the effect of β-glucans on the material and permeability properties of arabinoxylan-based films.     

Effects of Maillard reaction conditions on the antigenicity of α-lactalbumin and β-lactoglobulin in whey protein conjugated with maltose

The effects of Maillard reaction conditions (weight ratio of protein to sugar, temperature and time) on the antigenicity of α-lactalbumin (α-LA) and β-lactoglobulin (β-LG) in conjugates of whey protein isolate (WPI) with maltose were investigated. Response surface methodology was used to establish models to predict the antigenicity of α-LA and β-LG and find an optimal reaction condition under which the antigenicity of α-LA and β-LG reduces to minimum value. Conjugating WPI with maltose was an effective way to reduce the antigenicity of α-LA and β-LG. The antigenicity of α-LA decreased from 32.25 μg mL⁻¹ to 10.91 μg mL⁻¹. And the antigenicity of β-LG decreased from 272.4 μg mL⁻¹ to 38.17 μg mL⁻¹. Temperature had the greatest effect on the antigenicity of α-LA, while weight ratio of WPI to maltose was the most significant factor on the antigenicity of β-LG.     

Effect of Dietary Supplementation with α-Tocopheryl Acetate on the Stability of Reformed and Restructured Low Nitrite Cured Turkey Products

The objective of this study was to investigate the effects of sodium (Na) nitrite reduction on the oxidative and colour stability of reformed and restructured cured cooked turkey products manufactured from meat containing high and low levels of dietary α-tocopheryl acetate. Turkeys were randomly assigned to either a control group, fed a basal α-tocopheryl acetate diet (20mg/kg feed), or a treatment group fed a supplemented α-tocopheryl acetate diet (600mg/kg feed). Diets were fed ad libitum from day 1 until slaughter on day 147. Breast meat from control and treatment groups was used to manufacture cured reformed cooked turkey ham and cured restructured cooked turkey patties. Residual levels of 60 and 120mg Na nitrite/kg of meat were used. Turkey products were packaged in either overwrap or vacuum packaging and stored under refrigerated (4°C) illuminated display for 10 days. Results showed that dietary supplementation with α-tocopheryl significantly (p<0·05) improved the oxidative and colour stability of all low nitrite products produced when compared to non-supplemented controls.     

Effect of combined treatment of hydrolysis and polymerization with transglutaminase on β-lactoglobulin antigenicity

The effect of combined treatments of hydrolysis with different proteases, and subsequent polymerization with transglutaminase on the antigenic activity of β-Lg was studied. For the hydrolysis of β-Lg using Alcalase, Neutrase or bromelain, the reaction conditions were 3?% β-Lg and enzyme:substrate 25?U?g^?1 of protein, as was defined using factorial study. Under these conditions, the degree of hydrolysis (DH) of the hydrolysates was 12.6?% when obtained with Alcalase and approximately 4?% with Neutrase or bromelain. Post-hydrolysis polymerization did not result in an increase in molecular mass of the protein, but these samples presented a lower DH, determined by trinitrobenzenosulfonic acid (TNBS) method, suggesting that polymerization had occurred. Hydrolysis with the three enzymes reduced the β-Lg antigenicity, as evaluated by ELISA and immunoblotting analyses. The IgE-binding responses were practically null (<9?μg?mL^?1), 22.82 and 55.73?μg?mL^?1 towards the hydrolysates obtained with Alcalase, bromelain, and Neutrase, respectively. The post-hydrolysis polymerization increased or had no significant effect (P?≥?0.05) on the antigenic response of the hydrolysates.     

Effects of starches on the textural,rheological, and color properties of surimi–beef gels with microbial tranglutaminase

In order to evaluate effects of starches (corn starch, potato starch, and tapioca starch) on the characteristics of surimi–beef gels with microbial transglutaminase, the cooking loss, gel strength, color and rheological properties of samples were investigated. Results demonstrated that starches gave negative effects on the cooking loss of surimi–beef gels. The gel with corn starch had the highest cooking loss while that with tapioca starch showed the lowest value. The gel with potato starch obtained the highest gel strength. During the sol–gel transitions, surimi–beef complexes with 3% corn starch exhibited the highest storage modulus value, while that with 3% tapioca starch had the lowest one. The addition of starch caused the increase of L* values of surimi–beef gels. Results showed that the excessive amount of starch resulted in the decrease in gel strength of surimi–beef gels.