Whey protein coatings for enhancement of quality in peanuts and chocolates: Quality assessment using instrumental and sensory methods.

摘要

Edible coatings on food surfaces can provide a barrier to oxygen and protection from moisture migration into or out of the food, resulting in improved texture, color, aroma or flavor. Edible films and coatings offer additional functions, such as providing gloss to the surface to enhance the appearance of the food, adding structural integrity to improve mechanical-handling properties, and reducing complex packaging material which in turn reduces not only the cost of making the package but also reduces waste.; Whey protein isolate (WPI) is a highly purified protein product (90–95% protein, dry basis) which can be made into edible films and coatings, both in the native and denatured whey protein state. This dissertation consists of four different studies involving WPI-based coating applications on two different food systems: peanuts and chocolates. The objective of the peanut study was to determine the oxygen barrier property of the WPI-based coatings applied onto peanut surface using a commercial coating method. Peanut quality was analyzed by both instrumental and sensory methods. The objective of the chocolate study was to investigate the gloss enhancement and stabilization of the chocolate surface when applied with different WPI-based coating formulations, using instrumental gloss measurements and consumer testing.; WPI-based films have been found to be excellent oxygen barriers. Thus, we hypothesized that WPI films formed as coatings on peanuts would reduce peanut lipid oxidation. WPI-coated peanuts showed significantly less oxidation than the uncoated peanuts when measured by sensory and instrumental methods.; WPI coatings have been shown to provide gloss on model surfaces comparable to the conventionally-used alcohol-based shellac coatings. We hypothesized that whey protein coatings could be applied to chocolates and provide gloss levels similar to shellac. Glycerol, polyethylene glycol, propylene glycol and sucrose were used as different plasticizers in the coating formulation. The gloss from sucrose-plasticized coating showed the least fading after three months.; There was a significantly higher consumer acceptance for some of the WPI formulations over shellac. Therefore, water-based WPI coatings could be used as an alternative glaze with higher consumer acceptance than alcohol-based shellac.