DESIGN AND OPTIMIZATION OF ADVANCED EMULSIONS AS BIOACTIVE COMPOUND CARRIERS FOR LOW-SATURATED FAT FOOD PRODUCTS: TECHNOLOGICAL AND NUTRITIONAL ASPECTS
Research in food engineering is increasingly using reverse engineering principles to design healthier food products. Growing concerns about the high intake of fat-rich foods and the associated increased risk of chronic diseases like obesity, diabetes, and hypertension are driving the food industry to reformulate full-fat products by reducing total or saturated fat content while maintaining good physicochemical and sensory properties. However, fat provides the food matrix with important features, so its reduction or replacement can generate undesirable outcomes and unacceptability by consumers. One of the most promising strategies to reduce saturated fat content in foods is based on the use of emulsions. Particularly, advanced emulsions can prevent instability phenomena and provide new features, such as the ability to act as carriers for bioactive compounds and the possibility to engineer their interface to control digestive fate. In this context, the overarching goal of this PhD project was to design advanced emulsions intended as ingredients in low-saturated fat foods, and as potential bioactive compound carriers, thereby creating healthier products. At first, a complete literature survey about advanced emulsions in terms of composition and process conditions was performed to identify knowledge gaps and define experimental factors and the most suitable methods for emulsion characterization. Then the effect of emulsifier concentration and corn oil volume phase on single, Pickering, heat-filled gel, and cold-filled gel emulsions were studied by means of Design of Experiments techniques. Soy lecithin (SL), octenyl succinic anhydride starch (OSA), chickpea protein isolate (CPI), and citrus fibers (CF) were used as emulsifiers. Based on the highly significant models calculated for apparent viscosity and droplet size, emulsion formulations were optimized using Response Surface Methodology coupled with the desirability function. All optimized advanced systems outperformed the SL-based single emulsion, particularly in terms of apparent viscosity and stability index. To evaluate the digestion fate of the optimized emulsions produced with or without the addition of a commercial polyphenol extract, lipolysis was evaluated by applying the harmonized international protocol INFOGEST. There was no interaction between polyphenols and triacylglycerol hydrolysis, whereas the different emulsion structures influenced lipid digestibility. No differences were found in the free fatty acids release at the end of the intestinal phase. Still, significantly lower amounts of mono- and di-acylglycerols were found in the cold-gel emulsion with CF, which also showed the highest amount of unhydrolyzed triacylglycerols at the end of the gastric phase. The last part of the project focused on reformulating ice cream and cookies to obtain low-saturated fat products. Based on the previous results, CPI cold-gel emulsion was used as a substitute for milk cream in artisanal ice cream, while CPI heat-filled gel emulsion as butter replacer in cookies. The cold-filled gel emulsion produced an ice cream with quality properties comparable to those of the standard product but with improved nutritional features. As for cookies, the heat-filled gel emulsion resulted in higher protein and lower saturated fatty acids content with respect to the standard formulation, but the fracture strength was very high, thus further optimization of the formulation is needed. Studies about reformulated foods’ digestibility are still ongoing. Future studies should focus on encapsulated polyphenols’ fate during digestion, and on the use of enriched emulsions in food products.
Advanced emulsion, in-vitro digestibility, INFOGEST, ice cream, cookie, low-saturated fat, Settore AGRI-07/A - Scienze e tecnologie alimentari
Networked Digital Library of Theses and Dissertations