Comparison of Sweetened Condensed Skim Milk and Whey Protein Ingredients in Caramels
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Date
2003-12-08
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Abstract
Caramels may be described as 'soft glasses' that are viscous in nature and contain a dispersion of milk protein and an emulsion of fat. Milk proteins have traditionally been used in the confectionary industry for contributing distinct flavor, color, and texture, with sweetened condensed milk and milk powders being among the most popular. There are two main types of proteins in milk: caseins and whey proteins. Two popular ingredients made from whey proteins are whey protein isolates (WPI) and concentrates (WPC). Whey protein concentrates (WPC) contain between 25 and 80% protein and whey protein isolates (WPI) contain approximately 90% protein, with the remaining constituents being water, ash, lipid, and lactose. The goal of this research was to evaluate the acceptability and functionality of using whey protein ingredients in caramel confections by replacing the sweetened condensed skim milk with an imitation sweetened skim milk made with whey protein ingredients.
A control formula containing sweetened condensed skim milk (SCSM) and one with an imitiation sweetened condensed skim milk made with whey protein isolate (I-SCSM) were evaluated. Formulations were cooked to 113°C, 116°C, and 119&$176;C. Properties of both treatments were highly influenced by cook temperature. Creep recovery testing was used to evaluate viscoelastic properties of caramels. All caramels showed minimal recovery, indicating they were mainly viscous (fluid) in nature. Cold flow, the flow of caramels at room temperature over time under the force of gravity, was evaluated by measuring sample area over time. Minimal cold flow was seen in caramels cooked to 116 and 119°C. However, caramels cooked to 113°C showed cold flow in both formulations, with caramels made with WPI exhibiting more cold flow than the control caramel. There were perceptible color differences between control and those made with WPI processed to 119°C; however, few differences were seen at 113&3176;C and none were seen at 116°C. The relationship between glass transition temperature and maximum compliance was similar between both caramel treatments, suggesting no change in the mechanism responsible for rheological properties. Based on all of the properties measured, whey proteins can be substituted for SCSM in caramels with an endpoint temperature of 116°C. However, color and textural differences were seen at 113&$176;C and 119°C.
Based on the similarity seen in caramels made with WPI and SCSM, three brands of 34% whey protein concentrates (WPC) were explored as a more complex system containing higher levels of lipid, lactose, and minerals. There were no significant effects (p>0.05) due to brand of 34% whey protein concentrate (WPC) in compliance from the creep and recovery test, viscosity, percent recovery, glass transition temperature, moisture content or water activity. Differences due to WPC brand were seen in retardation time and color. A consumer acceptance test (n = 106) revealed that a caramel formulation made with one brand of WPC was similar to the control caramel with SCSM with the exception of stickiness.
Three brands of commercial caramels were evaluated in order to validate that the data from analytical testing was similar to that found in experimental caramels. Only slight differences were seen in rheological properties amongst commercial caramels and between commercial caramels and experimental caramels. Differences were mostly seen in color, which may be attributed to by final cook temperature (unknown) or ingredient formulations. Color values did fall within the range of experimental caramel formulations using SCSM, WPI, and WPC.
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Keywords
rheology, caramel, whey proteins, confectionary
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Degree
MS
Discipline
Food Science
