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The two biopolymers protein and starch are used to enhance the textural properties of food and play a key role in the formulation of novel food structures. In this paper, the interactions between dairy proteins and starch are discussed with a focus on the recent development on the rheological, pasting, and microstructural properties of these systems. Fortification of extruded cereal based snacks with dairy proteins leads to nutritious and energy dense snack foods. Milk proteins and starch interactions, and their effects on physiochemical and functional properties of extruded products are also explored in this review. Processing parameters of the extrusion process and feed characteristics affect final product quality and act as an important contributor in the determination of overall product texture. Fortification with dairy proteins may result in an acceptable quality of extrusion based ready to eat (RTE) snack foods. This review article will help food technologists to design and predict a product's behaviour during processing and final texture of a starch-protein based food system. Fax: þ64 3 325 3615Abbreviations: a-la, a-lactalbumin; b-lg, b-lactoglobulin; CLSM, confocal laser scanning microscopy; CWM, cross linked maize starch; DSC, differential scanning calorimetry; MPC, milk protein concentrate; PCS, phosphate crosslinked waxy maize starch; RTE, ready to eat; SMP, skim milk powder; SDS-PAGE, sodium dodecyl sulfate-Polyacrylamide gel electrophoresis; RVA, rapid visco analyser; WCF, water chestnut flour; WHC, water-holding capacity; WPC, whey protein concentrate; WPI, whey protein isolate

The impact of washing on the release of proteins from the milk fat globule membrane (MFGM) was examined by applying washing procedures with different degrees of stringency to milk fat globule (MFG) surfaces in simulated milk ultrafiltrate buffer solution. Three washing methods, M1 (3000g, 5 min, three washes), M2 (3750g, 15 min, one wash), and M3 (15000g, 20 min, three washes) were chosen. MFG ζ-potential increased after M3 washing (P < 0.05), suggesting surface damage. For M1, in which the native MFG surface was least damaged, cluster of differentiation 36 (CD 36) and periodic acid schiff 6/7 proteins were more strongly bound to the MFGM compared with other major membrane proteins. For M3, CD 36 together with fatty acid-binding protein was more strongly bound to the MFGM. Washing by centrifugation and redispersal of the fat globules damaged the MFGM, with release into the aqueous phase of some membrane-associated proteins. The current results show the impact of washing processes on retention of functional MFGM proteins.

Evidence for the asymmetric distribution of phospholipids in the milk fat globule membrane (MFGM) was obtained by applying 3 washing processes using aqueous solutions with different degrees of stringency (mild, intermediate, and intensive) to milk fat globule (MFG) surfaces in simulated milk ultrafiltrate buffer. We detected no change in the amount of cholesterol after the mild washing process; however, intensive washing yielded a relative enrichment of surface cholesterol with concomitant damage to the outer bilayer of the MFGM. This finding supports the hypothesis of repartitioning of cholesterol on MFG surfaces during mechanical treatments. An updated model system of lipid organization was developed according to the results of relative depletion of individual phospholipids, as analyzed by HPLC.

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Milk phospholipids (MPLs) have been used as ingredients for food fortification, such as bakery products, yogurt, and infant formula, because of their technical and nutritional functionalities. Starting from either buttermilk or beta serum as the original source, this review assessed four typical extraction processes and estimated that the life-cycle carbon footprints (CFs) of MPLs were 87.40, 170.59, 159.07, and 101.05 kg CO2/kg MPLs for membrane separation process, supercritical fluid extraction (SFE) by CO2 and dimethyl ether (DME), SFE by DME, and organic solvent extraction, respectively. Regardless of the MPL content of the final products, membrane separation remains the most efficient way to concentrate MPLs, yielding an 11.1–20.0% dry matter purity. Both SFE and solvent extraction processes are effective at purifying MPLs to relatively higher purity (76.8–88.0% w/w).

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