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Abstract
The aim of this research was to enzymatically modify menhaden oil with various acyl donors to produce structured lipids (SL). Using the Taguchi method, optimal reaction parameters for incorporating 30 mol% of C10:0 were 1:3 menhaden oil:ethyl caprate substrate molar ratio, 10% (w/w of total substrates) Lipozyme 435 lipase (from Candida antarctica), 60C temperature, and 24h reaction time. Linear interpolation determined substrate molar ratios that incorporated 20 or 30 mol% of caprylic or stearic acid. The 1:3.03 and 1:4.58 molar ratios resulted in incorporation of 20 and 30 mol% C8:0, respectively. The 1:1.32 and 1:2.41 molar ratios led to incorporation of 20 and 30 mol% C18:0, respectively. A 1:3:1 molar ratio (menhaden oil:C8:0:C18:0) led to incorporation of 14 mol% each of caprylic and stearic acid. The SL containing caprylic and/or stearic acid all had a melting point of 25-35C. For all SL, higher amounts of medium-long-medium (MLM)-type triacylglycerols (TAG) were formed using Lipozyme 435 as the biocatalyst. Organogels (also known as oleogels) of menhaden oil and SL were formed using two different organogelator blends (-sitosterol/-oryzanol or sucrose stearate/ascorbyl palmitate (SSAP)) at a 1:1 molar ratio. The organogels (SSAP: 72C, phytosterol: 68C) had higher melting completion temperatures than the menhaden oil (13C) and SL (14-35C). Physicochemical properties of the organogels depended on lipid and organogelator type. Encapsulation of these organogels in alginate microparticles led to a significant reduction in the amount of leaching (from 16-19% to 3-12%). Both organogels were also acceptable zero trans-fat substitutes for shortening in yellow cake by having similar physicochemical properties such as specific gravity (0.85), cake specific volume (0.99cm3/g), and rheological properties (Power-Law Model values of n:0.78 and k:31 Pa sn) to shortening. Organogelation and microencapsulation were both good methods for improving the oxidative stability of menhaden oil and SL (Oil Stability Index values from 4-18 h to 18-29 h when measured at 80C). These lipids may find use in a wide range of food and nutraceutical applications.