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Title:Evaluation of high intensity ultrasound on plant based lipid blends, containing health-promoting lipids, as an alternative to hydrogenation for plastic fat development
Author(s):Garrow, Linda S
Director of Research:Engeseth, Nicki J.
Doctoral Committee Chair(s):Lee, Youngsoo
Doctoral Committee Member(s):Gonzalez de Mejia, Elvira; Schmidt, Shelly J.
Department / Program:Food Science & Human Nutrition
Discipline:Food Science & Human Nutrition
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):nutritional lipid blend
high intensity ultrasound
trans fat free
Abstract:Trans fats are associated with increased risk for certain cancers, cardiovascular disease, diabetes, hypertension and obesity. While any food containing less than 0.5g of trans fat per serving can be labeled as containing zero grams of trans fat, the reality is that foods containing partially hydrogenated oils (PHO) contain manufactured trans fat. The discovery that manufactured trans fats are at least as harmful to human health as a diet rich in saturated fats fueled legislation from the Food and Drug Administration (FDA) resulting in the announcement in 2003 of an amendment to the Nutritional Labeling and Education Act requiring trans fats to be listed on nutrient labels, effective January 1, 2006. In anticipation of and in response to this ruling came the urgent need for shortening manufacturers and commercial shortening users to develop trans fat free alternatives or reformulate their products containing trans fat free shortenings, to significantly reduce the amount of manufactured trans fats in their formulation or to eliminate them completely. Researchers have shown that consumption of manufactured trans fats can lead to increased risk for certain cancers, cardiovascular disease, diabetes, hypertension and obesity. Information technology has permitted consumers to become increasingly aware of the composition of their food, such as the presence of additives, preservatives and the health effects of the types of fats they consume, prompting many food manufacturers to reformulate their lipid containing products to contain less than 0.5 gram trans fat per serving, the FDA definition of “trans fat free” for nutrient labels. In November 2013 the FDA opened a comment period until March 2014 to determine if PHOs, the major source of dietary trans fats, should no longer be generally recognized as safe (GRAS) and only be permitted in food by FDA approval as a food additive. Further legislative changes are still under review. Though it is well documented that blending of fats and oils, with or without interesterification, or development of organogels can produce trans free fats, few have produced lipids with plastic characteristics. The focus of these products has been to address the need to remove manufactured trans fats from the food supply, but few research laboratories have focused on nutritional elements of these new shortening formulations, such as medium chain fatty acids (MCFA) and endogenous antioxidants. Due to their small size, MCFAs are more soluble and are absorbed without the use of bile, then readily oxidized by the liver. They are commonly consumed by individuals with fat malabsorption diseases and have been suggested for weight-loss. Endogenous antioxidants in the individual lipid sources have already been documented as providing increased shelf-life stability by resisting lipid oxidation. Additionally, it has been suggested that consumption of endogenous plant antioxidants may have biological function providing potential resistance to certain cancers and cardiovascular disease. This project was developed with the hypothesis that the use of plant-based fats and oils, blended and treated with high intensity ultrasound would produce a trans fat free fat with plastic characteristics. Selected lipids may also provide health benefits and product shelf-life extension due to the presence of endogenous antioxidants and other potentially bioactive components. The standard protocol for preparing fat by blending is to combine components, heat to remove all crystal memory and cool rapidly with agitation to promote formation of numerous seed crystals, favoring the formation of the beta prime (β΄) polymorph, the crystal form that promotes plastic fat characteristics. This is tempered at 27-29°C for 24-48 hours. Utilization of high intensity ultrasound has resulted in alteration of the ratio and type of lipid crystals formed in chocolate and amorphous milk fat and was applied here to promote formation of the β΄ crystal polymorph. Different ratios of coconut oil, rice bran oil and palm stearin (dry fractionated from unrefined red palm oil) were blended, heated, and partially cooled prior to application of one or more high intensity ultrasound treatments. Blends were then rapidly cooled, with or without agitation, until firm. Blend characteristics from each treatment were evaluated by multiple methods including powder X-ray diffraction (XRD) to determine and quantify the types and quantity of crystals present. The presence of numerous small crystals is supportive of the presence of the β΄ polymorph and was evaluated by the application of polarized light microscopy (PLM). Oscillation rheology was used to characterize the solid-like (G’) and fluid-like (G”) behavior of the lipid samples. These properties were evaluated by a frequency strain sweep and a thixotropic loop at constant temperature (25°C). Fatty acid methyl esters were prepared from each sample and the fatty acid compositions compared to non-HIU treated blends. Additionally, saturation ratio (USFA/SFA) and chain-length ratio (MCFA:LCFA) were compared. Functionality/performance of the lipids was evaluated by preparation of a cookie and measurement of cookie width (W), thickness (T), spread ratio (W/T) and force to breaking point. A consumer sensory panel was used to determine overall likeability of the nutritional lipid blend (NLB) SCOR 12 when used in a baking application. An Orange-Coconut flavored cookie was prepared with NLB SCOR 12, commercial shortening (CS) or butter. There were three stages to the consumer sensory test. First, three cookies were sampled in the order provided and evaluated for overall likeability. Second, consumers were provided with information on the nutritional attributes of the three lipids used in the coded cookie samples then asked to taste each cookie again and rate them for likeability and third, complete a check-all-that-apply (CATA) ballot. XRD results indicated that the β΄ crystal polymorph was favored in the HIU-treated samples with one sample blend (SCOR 12) shifting from 66% β΄ (no HIU applciation) to 94% β΄ crystals (with HIU). For the blend PLM indicated smaller and more numerous fat crystals when compared with the non-HIU-treated NLB SCOR 12. The frequency stress sweep indicated that all blends were G’ dominant (G’>G”) displaying an elastic behavior rather than viscous behavior, which are indications for plastic fat functionality. This was further supported by comparison of thixotropic loops between HIU-treated blends and their non-treated counterparts, with the former rebuilding more quickly than the latter. Blend SCOR 12 had a saturation ratio of 0.32 and a chain-length ratio of 1.15, indicating that while over 50% of the fatty acids present in the sample were saturated more than 50% of these were medium chain fatty acids. Cookies made with HIU-treated blend SCOR 12 performed equal to, or better than, cookies made with CS (commercial plastic fat standard), producing a cookie with width and force to breaking point that were not significantly different from the CS cookie, the NLB cookie had significantly greater thickness. Overall, the cookie was accepted by consumers, but more so after being provided with the nutritional literature regarding the healthful components of the fat blend, the endogenous antioxidants and the high percentage of medium and short chain fatty acids. Many consumers indicated the orange coloration, due to the presence of endogenous carotenoid pigment, provided a pleasant color to the cookie. Additionally, there was agreement that the cookie was soft and moist without significant indication of greasiness. These results confirm that plant based lipid blends of coconut oil, rice bran oil and palm stearin, treated with high intensity ultrasound can produce a trans fat free fat with plastic characteristics necessary for many baking applications. Also, blending of these fats and oils resulted in a synergistic increase in radical scavenging capacity by their endogenous antioxidants.
Issue Date:2015-04-21
Type:Thesis
URI:http://hdl.handle.net/2142/78761
Rights Information:Copyright 2015 Linda Garrow
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015


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