Effects of protein–lipid and starch–lipid complexes on textural characteristics of extrudates based on wheat flour with the addition of oleic acid

The knowledge of biopolymer changes by extrusion is very important for a wide range of industrial applications that spreads from extruded food to biodegradable packaging. In this article, the formation of starch–lipid and lipid–protein complexes that occurred during the extrusion cooking of wheat flour with the addition of fatty acids was studied. Results showed that the highest barrel temperature (128.3 °C) promoted the formation of starch–lipid complexes in samples made up of wheat starch and wheat flour with the addition of fatty acids. The maximum formation of protein–lipid complexes (68% fatty acid bound to protein) was observed at the highest barrel temperature and water feed content (<22%). This study is a prerequisite for the optimisation of production of expanded extrudates made up of wheat flour and fatty ingredients and for the study of a biodegradable packaging based on by‐product of milling wheat (and fat).     

Influence of water on potato starch–lipid interactions. An electron spin resonance (ESR) probe study

Electron spin resonance (ESR) was used in order to study the mechanism of interaction of potato starch with lipids in systems with different water contents (40, 50 and 60% w/w) during heating and cooling. Different spin probes were used, on the one hand spin‐labelled stearic acids (5‐DSA and 16‐DSA), which limited lipids, and on the other hand the water‐soluble probe 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (Tempol), which was sensitive to changes in the dynamic properties of the water phase associated with the temperature‐induced starch structural transformations. Whatever the water content in the hydration range considered, Tempol was observed to be relatively mobile in the presence of potato starch, whereas a strong absorption of spin‐labelled stearic acids on potato starch granules took place at room temperature for all investigated starch–water systems. Spin‐labelled stearic acids were expected to stick on the starch granules. The mobility of the spin‐labelled stearic acid was less upon cooling than upon heating as a result of starch gelation. The mobility of spin probes decreased with increasing starch concentration. Introduction of a doxyl fragment at position 16 of the hydrocarbon chain leads to a lower degree of immobilisation of the spin probe as compared with 5‐DSA. This result suggests that there is a stronger interaction of polar sites of stearic acid with starch granules. © 2000 Society of Chemical Industry     

Effect of proteins on the formation of starch–lipid complexes during extrusion cooking of wheat flour with the addition of oleic acid

The formation of starch–lipid complexes plays an important role in extruded products. The effect of gluten proteins on thermal conditions at which the starch–lipid complexes formed during extrusion cooking of wheat flour with the addition of oleic acid was evaluated, considering wheat starch as a reference. The presence of gluten proteins in wheat flour extrudates brought about a reduction of the formation of starch–lipid complexes compared to blend of wheat starch and oleic acid extruded at the same operating conditions (melting enthalpy: 0.4 vs. 1.6 kJ kg^?1). Moreover, the lubricant effect of oleic acid observed during extrusion of wheat starch (low values of specific mechanical energy and residence time) was not found during extrusion of wheat flour with addition of oleic acid because of the interaction between gluten proteins and oleic acid. This research points out the importance of proteins on biopolymer modifications and their effect on extrudate quality.     

Influence of food structure on dairy protein,lipid and calcium bioavailability: A narrative review of evidence

Beyond nutrient composition matrix plays an important role on food health potential, notably acting on the kinetics of nutrient release, and finally on their bioavailability. This is particularly true for dairy products that present both solid (cheeses), semi-solid (yogurts) and liquid (milks) matrices. The main objective of this narrative review has been to synthesize available data in relation with the impact of physical structure of main dairy matrices on nutrient bio-accessibility, bioavailability and metabolic effects, in vitro, in animals and in humans. Focus has been made on dairy nutrients the most studied, i.e., proteins, lipids and calcium. Data collected show different kinetics of bioavailability of amino acids, fatty acids and calcium according to the physicochemical parameters of these matrices, including compactness, hardness, elasticity, protein/lipid ratio, P/Ca ratio, effect of ferments, size of fat globules, and possibly other qualitative parameters yet to be discovered. This could be of great interest for the development of innovative dairy products for older populations, sometimes in protein denutrition or with poor dentition, involving the development of dairy matrices with optimized metabolic effects by playing on gastric retention time and thus on the kinetics of release of the amino acids within bloodstream.     

Tannin–protein interaction is more closely associated with astringency than tannin–protein precipitation: experience with two oenological tannins and a gelatin

Relative abilities of two commercial oenological tannins to interact with a single oenological gelatin were compared with their relative abilities to elicit astringency. A trained sensory panel assessed astringency, whereas the interaction between tannins and gelatin was estimated by observing the ability of tannins both to interfere with gelatin diffusion on a cellulose membrane and to form tannin–gelatin precipitates. HPLC‐DAD chromatography and spectroscopic analysis showed that one of the commercial tannins was a hydrolysable tannin, while the other one was a condensed. The majority of the sensory panelists recognised the hydrolysable tannin as far more astringent than the condensed. The more astringent oenological tannin was found to interfere markedly with gelatin diffusion on a cellulose membrane, but it failed to produce tannin–gelatin precipitation. The condensed oenological tannin both interfered with gelatin diffusion and was a powerful gelatin‐precipitant. This study supports the hypothesis that astringency correlates better with tannin–gelatin interaction than tannin–gelatin precipitation.     

Hydrocolloids from coffee: physicochemical and functional properties of an arabinogalactan–protein fraction from green beans

The arabinogalactan–protein (AGP) fraction of green coffee beans accounts for 15% of the dry bean. A procedure was developed to solubilise most of the AGP content of the beans so that its properties as a hydrocolloid could be investigated. An AGP fraction was partially purified from green arabica coffee beans, its rheological properties characterised and compared to those of some commercially important hydrocolloids, particularly acacia gum. The coffee AGP fraction dissolved readily in water to give colourless clear solutions. The polymer was a polyelectrolyte with a high molecular weight (M_w 3.78×10⁶), characterised by a narrow polydispersity index (M_w/M_n 1.3). The intrinsic viscosity was close to that of acacia gum ([η]=0.23 dL g⁻¹), but a 1 wt% solution of coffee AGP was three times more viscous than acacia gum at the same concentration. Coffee AGP showed Newtonian flow for concentrations below 6 wt%, but above this concentration the flow behaviour entered a shear-thinning regime. The coffee AGP fraction possessed interesting foaming properties providing that the biopolymer concentration was high enough to initially stabilize the interface that is created. The high molecular weight of coffee AGP combined with its globular structure conferred upon it a high ability to retain water within a foam thin film. However, the structure of the interfacial film was less effective than that of acacia gum to entrap efficiently the gas into the foam. In summary, coffee AGP shows some interesting rheological features which suggest that coffee beans could be used as an alternative source of the class of surface-active polymers which find many commercial applications.     

A review of methods used for investigation of protein–phenolic compound interactions

Interactions between the different compounds present in foods are common and have influence on the nutritional and functional properties of food products. Among a wide range of these interactions, the formation of complexes between proteins and phenolic compounds seems to be the most important issue. Complexation of the phenolic compounds with proteins can be analysed considering several aspects. These complexes might strongly affect nutritional potential of polyphenols by masking their antioxidant capacity, and on the other hand might have influence on the structure of proteins which may cause their precipitation or decrease susceptibility to digestion. The complexity of protein–phenolic compound interactions is a challenge for food analysts and forced researchers to establish a wide range of analytical methods, allowing determination of complexes formation. The main aim of this review is to give researchers an overview of the currently used methods that can be applied to study the interactions between proteins and phenolic compounds.     

Characterisation and yield of the arabinogalactan–protein mucilage of taro corms

The main component of the taro corm is starch but appreciable quantities of water‐soluble mucilage are also present. Taro mucilage was cold‐water extracted and purified by dispersion and hydrolysis of starch, removal of starch hydrolysate and unconjugated protein. Compositional analysis of purified cold‐water‐soluble taro mucilage (PCWX) showed that galactose and arabinose were the main monosaccharides in the hydrolysate of PCWX and that the main polymer present was an arabinogalactan–protein. The yield of mucilage from 12 taro varieties varied from 75.7 to 137.0 g kg⁻¹ (dry wt basis) amongst different varieties. The purity of the final mucilage arabinogalactan was confirmed by ion‐exchange chromatography and electrophoresis. © 1999 Society of Chemical Industry     

Preparation and characteristics of yak casein hydrolysate–iron complex

The effect of mass ratio between yak casein hydrolysate and FeSO₄, reaction temperature, pH and holding time on ferrous‐binding capacity of yak casein hydrolysate was investigated. Iron‐releasing percentage and structural characteristics of the formed yak casein hydrolysate–iron complex were also examined. Results showed that casein hydrolysates with different hydrolysis degrees (DH) possessed different ferrous‐binding capacities with the highest of 7‐h hydrolysate. The optimal binding conditions between yak casein hydrolysate and iron are mass ratio of casein hydrolysate to FeSO₄ of 15:1 for 20 min at 40 °C and pH 6.0. The principal binding site for Fe²⁺ in yak casein hydrolysate consists of the carboxylate groups and amide groups. Compared with ferrous sulphate, yak casein hydrolysate–iron complex has higher iron‐releasing percentage at basic conditions, such as pH 7.0, 7.5 and 8.0. Ferrous‐iron enriched casein hydrolysate, i.e. yak casein hydrolysate–iron complex, may have great potential as an effective delivery vehicle of bioavailable iron.     

Functional and bioactive properties of fish protein hydolysates and peptides: A comprehensive review

Global fish processing industries dispose of fish wastes that account for more than 60% of processed fish biomass. In lieu of environmental pollution and disposal problems, these wastes are used to produce fish silage, fishmeal and sauce. They are also utilized for the production of value added products such as proteins, hydrolysates, bioactive peptides, collagen and gelatin. Research on the production of fish protein hydroysates (FPHs) presently focuses on maximizing the industrial potential of fish wastes. Since bioactive peptides containing amino acids hold properties of great interest, this paper reviews current research on the functional and bioactive properties of FPHs with an additional focus on gaps between fish and other hydrolysates, as well as current and future trends for the productive utilization of FPHs.     

Effects of ball‐milling treatment on mussel (Mytilus edulis) protein: structure,functional properties and in vitro digestibility

In this study, the effects of ball‐milling treatment on structural properties and functional properties of mussel protein were investigated. In vitro protein digestibility and free amino acid contents were also evaluated. Ball‐milling treatment did not change the primary structure of mussel protein, but caused changes of secondary structure. The tertiary and quaternary structure also changed. After 20 min of ball‐milling treatment, the whiteness and oil‐binding capability of mussel protein significantly improved from 13.67 to 26.62 and 43.76% to 196.00%, while the protein solubility and water‐holding capability of mussel protein significantly decreased from 74.89% to 53.10% and 215.67% to 90.91%. Ball‐milling treatment increased the in vitro digestibility significantly. These results provide theoretical basis for the utilisation of mussel protein in food industry.