D. Julian McClements

Molecular basis of protein functionality with special consideration of cold-set gels derived from heat-denatured whey

Abstract Whey proteins are widely used as ingredients in foods because of their unique functional properties, i.e. emulsification, gelation, thickening, foaming and water-binding capacity. This review describes the recent development of cold-setting whey protein ingredients and their potential application in foods. We emphasize the importance of an understanding of the molecular basis of protein functionality to the development of ingredients.

Advances in the application of ultrasound in food analysis and processing

Ultrasonic techniques are finding increasing use in the food industry for both the analysis and modification of foods. Low-intensity ultrasound is a non-destructive technique that provides information about physicochemical properties, such as composition, structure, physical state and flow rate. High-intensity ultrasound is used to alter, either physically or chemically, the properties of foods, for example to generate emulsions, disrupt cells, promote chemical reactions, inhibit enzymes, tenderize meat and modify crystallization processes.

Role of Physical Structures in Bulk Oils on Lipid Oxidation

Lipid oxidation is important to food manufacturers especially when they increase unsaturated lipids in their products to improve nutritional profiles. Unfortunately, the number of antioxidants available to food manufacturers to control oxidative rancidity is limited and the approval of new antioxidants is unlikely due to economic barriers in obtaining government approval for new food additives. Therefore, new antioxidant technologies are needed for food oils. This paper reviews the current knowledge of lipid oxidation in foods with emphasis on how physical properties of food systems impact oxidation chemistry. In particular, the role of association colloids in bulk oils on lipid oxidation chemistry is discussed in an attempt to understand mechanisms of oxidation. Increasing the understanding of how physical properties impact lipid oxidation could lead to the development of novel antioxidant technologies that not only protect the oil against oxidation and increase shelf-life but also allow food manufacturers to include more nutritionally beneficial fatty acids in their products.

Factors Influencing the Chemical Stability of Carotenoids in Foods

In recent years, a number of studies have produced evidence to suggest that consuming carotenoids may provide a variety of health benefits including a reduced incidence of a number of cancers, reduced risk of cardiovascular disease, and improved eye health. Evolving evidence on the health benefits of several carotenoids has sparked interest in incorporating more carotenoids into functional food products. Unfortunately, the same structural attributes of carotenoids that are thought to impart health benefits also make these compounds highly susceptible to oxidation. Given the susceptibility of carotenoids to degradation, particularly once they have been extracted from biological tissues, it is important to understand the major mechanisms of oxidation in order to design delivery systems that protect these compounds when they are used as functional food ingredients. This article reviews current understanding of the oxidation mechanisms by which carotenoids are degraded, including pathways induced by heat, light, oxygen, acid, transition metal, or interactions with radical species. In addition, several carotenoid delivery systems are evaluated for their potential to decrease carotenoid degradation in functional food products.

Advances in Food Colloids

Trends And Developments. Molecular Basis of Protein Functionality. Protein Polysaccharide Interactions. Computer Simulation. Application of Nuclear Magnetic Resonance to Food Emulsions. Ultrasonic Characterization of Food Colloids. Fat Crystallization in Oil in Water Emulsions. Surfactant Micelles in Food. Water-in-Oil-in-Water Multiple Emulsion. More Advances and Challenges. Index

Lipid Oxidation in Food Emulsions

Lipid oxidation is a major cause of quality deterioration in food emulsions. The design of foods with improved quality depends on a better understanding of the physicochemical mechanisms of lipid oxidation in these systems. The oxidation of emulsified lipids differs from that of bulk lipids, because of the presence of the droplet membrane, the interactions between the ingredients, and the partitioning of ingredients between the oil, aqueous and interfacial regions.

Recent Advances in Edible Coatings for Fresh and Minimally Processed Fruits

The development of new edible coatings with improved functionality and performance for fresh and minimally processed fruits is one of the challenges of the post harvest industry. In the past few years, research efforts have focused on the design of new eco-friendly coatings based on biodegradable polymers, which not only reduce the requirements of packaging but also lead to the conversion of by-products of the food industry into value added film-forming components. This work reviews the different coating formulations and applications available at present, as well as the main results of the most recent investigations carried out on the topic. Traditionally, edible coatings have been used as a barrier to minimize water loss and delay the natural senescence of coated fruits through selective permeability to gases. However, the new generation of edible coatings is being especially designed to allow the incorporation and/or controlled release of antioxidants, vitamins, nutraceuticals, and natural antimicrobial agents by means of the application of promising technologies such as nanoencapsulation and the layer-by-layer assembly.

Iron-catalyzed lipid oxidation in emulsion as affected by surfactant, pH and NaCl

Abstract Corn oil-in-water emulsions stabilized by sodium dodecyl sulfate (SDS), Brij 35 or dodecyltrimethylammonium bromide (DTAB) were prepared to determine the influence of surface charge on iron-catalyzed lipid oxidation. Oxidation was measured using lipid peroxides, conjugated dienes, and thiobarbituric reactive substances. At pH 6.5, initial oxidation rates were in the order of SDS> Brij>DTAB. As pH was decreased from 8 to 3, oxidation of SDS-stabilized emulsions increased, while oxidation of Brij and DTAB emulsions were unaffected. NaCl (1.0%) decreased oxidation of the SDS-stabilized emulsion by 20% but had minimal influence on oxidation of Brij and DTAB emulsions. These results indicate that the surface charge of emulsion droplets plays an important role in their oxidative stability.

Relationships between free radical scavenging and antioxidant activity in foods

Numerous attempts have been made to relate the free radical scavenging capacity of compounds to their antioxidant activity in foods even though antioxidant activity is dependent on both physical and chemical properties. The objective of this study was to compare the free radical scavenging activity of various compounds to their ability to inhibit lipid oxidation in foods. The order of free radical scavenging activity of polar compounds was ferulic acid > coumaric acid > propyl gallate > gallic acid > ascorbic acid as determined by a modified oxygen radical absorbance capacity, while the order of nonpolar compounds was rosmarinic acid > butylated hydroxytoluene >or= tert-butylhydroquinone (TBHQ) > alpha-tocopherol as determined by the 2,2-diphenyl-1-picrylhydrazyl assay. Of these compounds, only propyl gallate and TBHQ were found to inhibit lipid oxidation in cooked ground beef as determined by thiobarbituric acid reactive substances, while only propyl gallate, TBHQ, gallic acid, and rosmarinic acid inhibited lipid oxidation in an oil-in-water emulsion as determined by lipid hydroperoxides and headspace hexanal. These data indicate that the free radical scavenging assays tested have limited value in predicting the antioxidant activity in complex foods.

Production and characterization of oil-in-water emulsions containing droplets stabilized by β-lactoglobulin-pectin membranes

Oil-in-water emulsions containing droplets stabilized by beta-lactoglobulin (beta-Lg)-pectin membranes were produced using a two-stage process. A primary emulsion containing small droplets (d(32) approximately 0.3 microm) was prepared by homogenizing 10 wt % corn oil with 90 wt % aqueous solution (1 wt % beta-Lg, 5 mM imidazole/acetate buffer, pH 3.0) using a high-pressure valve homogenizer. The primary emulsion was then diluted with pectin solutions to produce secondary emulsions with a range of pectin concentrations (5 wt % corn oil, 0.45 wt % beta-Lg, 5 mM imidazole/acetate buffer, 0-0.22 wt % pectin, pH 3.0). The electrical charge on the droplets in the secondary emulsions decreased from +33 +/- 3 to -19 +/- 1 mV as the pectin concentration was increased from 0 to 0.22 wt %, which indicated that pectin adsorbed to the droplet surfaces. The mean particle diameter of the secondary emulsions was small (d(32) < 1 microm) at relatively low pectin concentrations (<0.04 wt %), but increased dramatically at higher pectin concentrations (e.g., d(32) approximately 13 microm at 0.1 wt % pectin), which was attributed to charge neutralization and bridging flocculation effects. Emulsions with relatively small mean particle diameters (d(32) approximately 1.2 microm at 0.1 wt % pectin) could be produced by disrupting flocs formed in secondary emulsions containing highly negatively charged droplets, for example, by sonication, blending, or homogenization. The particles in these emulsions probably consisted of small flocs containing a number of protein-coated droplets bound together by pectin molecules. These emulsions had good stability to further particle aggregation up to relatively high ionic strengths (< or =500 mM NaCl) and low pH (pH 3). The interfacial engineering technology used in this study could lead to the creation of food emulsions with improved physicochemical properties or stability.