Preparation,characterisation and activity of the inclusion complex of paeonol with β-cyclodextrin

The inclusion complex of β-cyclodextrin (β-CD) and paeonol (2′-hydroxy-4′-methoxyacetophenone, PAE) was synthesised and characterised by thermal gravimetric analysis (TGA) and two-dimensional rotating frame spectroscopy (2D ROESY). The antioxidant activity and tyrosinase inhibition activity were also studied. The TGA results indicated that the thermal stability of PAE was improved when it was included with β-CD. Based on the 2D ROESY analysis, an inclusion structure of the PAE–β-CD complex was proposed, in which PAE penetrated β-CD in a tilted manner due to the interaction of intermolecular hydrogen bonds between PAE and β-CD. The complex of PAE with β-CD increased the antioxidant activity and tyrosinase-inhibiting activity of PAE.     

Structural characterisation,gastrointestinal digestion stability and transepithelial transport study of casein peptide–zinc chelate

In this study, a promising nanoparticle of casein peptide–zinc chelate (CNP-Zn) for zinc supplementation was obtained. The structure properties and transepithelial transport mechanism were investigated. The amino acid composition, particle size, zeta potential and microstructure were significantly changed after chelation with zinc ions. The results of fourier-transform infrared spectroscopy suggested that the oxygen atoms from both the carboxyl and carbonyl groups, amides, were responsible for zinc chelation. After gastrointestinal digestion, over 40% of zinc remained bound in CNP–Zn. The transepithelial transport results showed that paracellular route and PepT1 transporter were involved in the absorption of CNP–Zn, and almost 50% of the bound zinc was co-transported with peptides. These findings would provide a relatively comprehensive cognition for developing efficient dietary zinc carriers.     

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.     

Preparation,physicochemical characterization and release behavior of the inclusion complex of trans-anethole and β-cyclodextrin

Trans-anethole (AT) has a variety of antimicrobial properties and is widely used as food functional ingredient. However, the applications of AT are limited due to its low water solubility, strong odor and low physicochemical stability. Therefore, the aim of this work was to encapsulate AT with β-cyclodextrin (β-CD) for obtaining inclusion complex by co-precipitation method. The measurements effectively confirmed the formation of inclusion complex between AT and β-CD. The results showed that the inclusion complex presented new solid crystalline phases and was more thermally stable than the physical mixture and β-CD. The phase solubility study showed that the aqueous solubility of AT was increased by being included in β-CD. The calculated stability constant of inclusion complex was 1195 M^− 1, indicating the strong interaction between AT and β-CD. Furthermore, the release study suggested that β-CD provided the protection for AT against evaporation. The release behavior of AT from the inclusion complex was controlled.     

Enzymatic scouring and bleaching of cotton terry fabrics – opportunity of the improvement on some physicochemical and mechanical properties of the fabrics

In the present study, an attempt was made to treat cotton terry fabrics with alkaline pectinase enzyme and observe the effects on the properties including the degree of whiteness, water absorbency, pill formation, weight loss after abrasion, tenacity at maximum load, degree of polymerization (DP), and hand feeling of the fabric. The enzymatic treatment of cotton terry fabrics had a positive influence on some of their properties. The degree of damage of cotton terry fabrics after 20 washings in a domestic washing machine was determined by analyzing the tenacity at maximum load, weight loss after abrasion, fabric hand feeling, and the DP. Enzymatic-scoured fabrics had a higher resistance to abrasion, a lower decrease in the DP, and a higher rating of the fabric hand feeling compared with alkaline-scoured fabrics. Enzymatic processing was accompanied by a significant lower demand of energy and water. Consequently, at these processes arises the lowest amount of effluents and the produced wastewater is biodegradable. This study attempted to introduce enzymatic scouring (ES) and bleaching with peracetic acid (PAA) of the cotton terry fabrics.     

Barley: Impact of processing on physicochemical and thermal properties—A review

Barley (Hordeum vulgare L.) is a nutritious cereal but very little (only about 2%) of this grain is used as human food. However, it has attracted the attention of researchers and food processors in the last 15 years for its potential health benefits. It is also recognized as a functional grain because it contains high levels of β-glucan and phytochemicals. Therefore, a number of barley processing research and animal/clinical trials have been performed over the last 15–20 years. Also, health claims have been approved by a number of government agencies including the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) about consumption of β-glucan, an important component of barley. Barley must undergo various processing steps before human consumption, which greatly affect their composition and physicochemical properties. These properties play an important role in the development of new products. Therefore, the present article reviews the literature on the effect of processing on the physicochemical and thermal properties of barley.     

Comparison of the gel-forming ability and gel properties of α-lactalbumin,lysozyme and myoglobin in the presence of β-lactoglobulin under high pressure

α-Lactalbumin (α-La) and lysozyme (LZM) each contain four disulfide bonds but no free SH group, whereas myoglobin (Mb) possesses no disulfide bond or free SH group. In this work, the pressure-induced gelation of α-La, LZM and Mb in the absence and in the presence of β-lactoglobulin (β-Lg) was studied. Solutions of α-La, LZM and Mb (1–24%, w/v) did not form a gel when subjected to a pressure of 800 MPa and circular dichroism analysis revealed that both α-La and LZM are pressure-resistant proteins. In the presence of β-Lg (5%, w/v), however, a pressure-induced gel formed for α-La and LZM (each 15%, w/v) but not for Mb (15%, w/v). One- and two-dimensional SDS-PAGE demonstrated the disulfide cross-linking of proteins was responsible for the gelation. Although α-La and LZM are homologous and have the same disulfide bond arrangement, the texture and appearance of the gels formed from α-La/β-Lg and LZM/β-Lg were markedly different even when induced under the same experimental conditions. Microscopic analysis indicated that phase separation occurs during the gelation of LZM/β-Lg but not during the gelation of α-La/β-Lg. NMR relaxation measurement revealed that the association of water molecules with the protein matrix in the α-La/β-Lg gel is tighter compared to that in the LZM/β-Lg gel. These results indicate that the gel-forming ability of a globular protein under high pressure is related to the primary structure of the protein, and that the gel properties depend on the cross-linking reaction and on the phase behavior of protein dispersion under high pressure.     

A review of the structure,function, and application of plant-based protein–phenolic conjugates and complexes

Interactions between plant-based proteins (PP) and phenolic compounds (PC) occur naturally in many food products. Recently, special attention has been paid to the fabrication of PP–PC conjugates or complexes in model systems with a focus on their effects on their structure, functionality, and health benefits. Conjugates are held together by covalent bonds, whereas complexes are held together by noncovalent ones. This review highlights the nature of protein–phenolic interactions involving PP. The interactions of these PC with the PP in model systems are discussed, as well as their impact on the structural, functional, and health-promoting properties of PP. The PP in conjugates and complexes tend to be more unfolded than in their native state, which often improves their functional attributes. PP–PC conjugates and complexes often exhibit improved in vitro digestibility, antioxidant activity, and potential allergy-reducing activities. Consequently, they may be used as antioxidant emulsifiers, edible film additives, nanoparticles, and hydrogels in the food industry. However, studies focusing on the application of PP–PC conjugates and complexes in real foods are still scarce. Further research is therefore required to determine the structure–function relationships of PP–PC conjugates and complexes that may influence their application as functional ingredients in the food industry.     

Role of β-conglycinin and glycinin subunits in the pH-shifting-induced structural and physicochemical changes of soy protein isolate

Soy β-conglycinin (7S) and glycinin (11S) were incubated up to 4 h in acidic (pH 1.5 to 3.5) or alkaline (pH 10 to 12) solutions to induce protein structural unfolding followed by refolding 1 h at pH 7.0, a process known as pH-shifting. The pH-shifting markedly increased (P < 0.05) emulsifying activity of 11S and to a lesser extent 7S; the former also produced more uniform oil droplets. The emulsifying activity improvements were accompanied by a significant rise in protein surface hydrophobicity, slight loss of the secondary structure (circular dichroism), and substantial dissociation of disulfide-linked basic and acidic 11S subunits. The findings suggested that 11S globulins of soy protein isolate (SPI) were more responsive to pH-shifting treatments than were 7S globulins, and the resulting emulsifying activity enhancements of 11S, in parallel with that of SPI, were indicative of its determinant role in the overall emulsifying properties of pH-shifting-treated SPI. PRACTICAL APPLICATION: Extreme alkaline (pH 12) and acidic (pH 1.5) medium treatments can significantly modify the structure and enhance the emulsifying properties of both β-conglycinin and glycinin components of SPI. The functionality improvement by the pH processes is more remarkable for the glycinin protein fraction. Therefore, SPI enriched with glycinin seems to be particularly suitable for extreme acidic or alkaline processes to produce surface-active functional ingredients for food applications.     

Surface viscosity of glycosylated derivatives of beta-lactoglobulin at the air—water interface

Surface viscosities of beta-lactoglobulin (βLG) and glycosylated derivatives of βLG were determined at the air—water interface using a rotational viscometer. The surface viscosity of 0.1% solutions increased rapidly during the first few minutes and then decreased slightly. Surface viscosity and rate of development of surface viscosity were maximum near the isoelectric point of βLG. Glycosylation of βLG decreased its rate of development and maximum surface viscosity. Apparently, surface viscosity was affected by decreased electrostatic repulsions and increased hydrophilic interactions, protein conformational stability and the interfacial concentration of βLG. The shearing action of the viscometer probably contributed to surface viscosity by increasing the rate of protein adsorption and desorption and increasing the entanglement of proteins at the air—water interface. This study increases our understanding of the protein structure—function relationships in foams and emulsions.     

Effect of the incorporation of antioxidants on physicochemical and antioxidant properties of wheat starch–chitosan films

Blend edible films were prepared from wheat starch (WS) and chitosan (CH) with glycerol as plasticizer. Four active ingredients (antioxidants) were added, namely basil essential oil, thyme essential oil, citric acid and α-tocopherol. The starch:antioxidant mass ratio was 1:0.1. Prior to characterisation, the films were conditioned at 25 °C–53%RH as to their structural, mechanical, optical and barrier properties. The antioxidant capacity of the active ingredients was determined by means of a spectrophotometric method. The incorporation of antioxidants led to a heterogeneous film microstructure, mainly in those containing α-tocopherol, which affected the surface roughness. Yellowness was induced in films when α-tocopherol was added and no notable colour changes were observed in the other cases, although all the antioxidants increased the transparency of the films. Despite of the fact that the mechanical properties were barely affected by the incorporation of antioxidants, citric acid promoted an increase in the elastic modulus but a decrease in film stretchability. The water vapour barrier properties of the films were only slightly improved when citric acid and α-tocopherol were added, whereas the oxygen barrier properties were significantly improved in all cases. The greatest antioxidant capacity of the films was reported for films containing α-tocopherol, which exhibited the highest antioxidant power.     

A large-scale isolation of native β-lactoglobulin: characterization of physicochemical properties and comparison with other methods

A novel method for β-lactoglobulin (β-lg) isolation from whey was investigated. The method comprised a peptic treatment of whey and membrane filtration under gentle conditions for isolation of native β-lg. The method was applied to 10,000 L batches of processed whey and the product quality obtained was compared with pilot-scale results of three other procedures: 3% trichloroacetic acid (TCA) precipitation, a salting-out procedure and a selective thermal precipitation. The calculated yields of native β-lg were 67.3, 44.9, 46.7 and 49.6% of the β-lg present in whey using the four methods, respectively. The composition of the different β-lg preparations was found to be comparable, however, analysis of purity revealed slight differences as indicated by electrophoresis and fast protein liquid chromatography (FPLC). The isolated β-lg retained a high degree of purity and native properties. The new method for isolation of native β-lg was found to be reproducible, selective and robust as processing of three 10,000 L batches did not indicate any technical problems or variations in the purity of the isolated β-lg.     

High pressure processing effects on the molecular structure of ovalbumin,lysozyme and β-lactoglobulin

Structural changes to the three sensitive food proteins, ovalbumin, β-lactoglobulin and lysozyme were examined following a series of high pressure processing experiments. The proteins prepared at specific pH were pressurized up to 600 MPa and held for periods of up to 30 min. Changes to the secondary and tertiary by examination of circular dichroism spectra revealed that the structure of the three proteins behaved differently to both the applied pressure and holding time. The notable effects were found to occur to both ovalbumin and β-lactoglobulin while lysozyme was found to be the most pressure resistant. For each of the proteins, it also appears that the processing conditions applied at specific pH act in combination to bring about structural change.     

Effects of oxidative treatment on the physicochemical,rheological and functional properties of oat β-glucan

The objective of this work was promote oxidation of β-glucan from oat bran with hydrogen peroxide at different concentration levels (0.3%, 0.6% and 0.9% H₂O₂) and reaction times (30 and 60 min), and evaluate the physicochemical and functional properties of isedoxidised β-glucan with in-vitro tests. An increase in carbonyl and carboxyl groups and alterations in swelling power were verified in the oxidised β-glucan. The cholic acid binding capacity increased in the oxidised β-glucan; however, the fat binding capacity was not affected. After chemical digestion, the available glucose of the oxidised β-glucan was increased. Oxidation with hydrogen peroxide decreased the viscosity, hardness, adhesiveness and gumminess of the β-glucan gels. More studies are necessary to determine the effect of the oxidative treatment of β-glucan on its technological properties in food products, and biological properties should be examined with in-vivo studies.     

Influence of ι-carrageenan, pectin, and gelatin on the physicochemical properties and stability of milk protein-stabilized emulsions

This study evaluated the stability of bilayer emulsions as a function of secondary layer composition and pH. Primary emulsions were formulated with 5% soybean oil, 1% protein from nonfat dry milk (NDM) powder as emulsifier and ι-carrageenan (ι-carr), low-methoxyl pectin (LMp), high-methoxyl pectin (HMp), or gelatin as secondary layers. ζ-Potential values increased for each emulsion as the pH decreased, with ι-carr emulsions being consistently more negatively charged than primary emulsions and significantly more stable. ζ-Potential values were not always correlated to emulsion stability. Gelatin secondary emulsions at pH 3 and HMp secondary emulsions at pH 7 were unstable due to the presence of depletion flocculation. In addition, LMp secondary emulsions stability at pH 7 might be due to calcium bridging, which increased the emulsion's viscosity. Overall, the stability of NDM emulsions was improved when ι-carr and LMp were used as secondary layers at pH 7 and 5, and when ι-carr and HMp were used as secondary layers at pH 3. Increased stability of these systems can be attributed to a second homogenization step used to formulate the secondary emulsions and to the presence of Ca(+2) in the NDM. Results from this research show that the stability of bilayer emulsions is driven by the presence of depletion flocculation, droplet charge, droplet size and distribution and viscosity. PRACTICAL APPLICATION: The use of everyday ingredients (nonfat dry milk powder, gelatin, pectin, and carrageenan), which are understood and accepted by the average consumer, creates label-friendly products that are the wave of the future. Stable emulsions can be formed using these ingredients at various pH. Understanding the stability and how the pH impacts the physicochemical characteristics and stability of these emulsions will enable manufactures to use ordinary ingredients to create healthier products (for example, low-fat dressings, sauces, dips, and beverages).     

Biochemical characterisation of α-amylase inhibitors from Achyranthes aspera and their interactions with digestive amylases of coleopteran and lepidopteran insects

BACKGROUND: Starchy seeds are an important food and a source of dietary ingredients in many countries. However, they suffer from extensive predation by bruchids (weevils) and other pests. α‐Amylase inhibitors are attractive candidates for the control of seed weevils, as these insects are highly dependent on starch as an energy source. RESULTS: A proteinaceous α‐amylase inhibitor from the seeds of Achyranthes aspera was identified, purified and characterised. In electrophoretic analysis, two prominent amylase inhibitor activity bands (AI1 and AI2) were detected. The inhibitor was purified 9.99‐fold with 1206.95 total amylase inhibitor units mg^?1 protein. The molecular weight of the purified inhibitor was around 6 kDa. The isolated α‐amylase inhibitor was found to be resistant to heat and proteolysis. Feeding analysis of Callosobruchus maculatus larvae on a diet containing seed powder of A. aspera revealed that survival of the larvae was severely affected, with the highest mortality rate occurring on the fifth day of feeding. The isolated inhibitor inhibited the majority of amylase isoforms of C. maculatus, Tribolium confusum and Helicoverpa armigera in electrophoretic analysis and solution assays. CONCLUSION: The information obtained in the present investigation could be useful for a genetic engineering approach that would make seeds resistant to storage pest infestations. Copyright © 2011 Society of Chemical Industry