Crystallization Kinetics of Coconut Oil in the Presence of Sorbitan Esters with Different Fatty Acid Moieties

Sorbitan esters (SEs) are shown to strongly influence the solidification kinetics and fat crystal morphology, but not polymorphic behaviour, of coconut oil (CNO). Solid‐state SEs (sorbitan monopalmitate, monostearate, and tristearate) affect both the high‐ and low‐melting fractions of CNO by decreasing induction time and by increasing crystallization rate as well as the number concentration of crystals. Liquid‐state SEs (sorbitan monoleate and trioleate) and canola oil do not specifically influence the high‐ or low‐melting fraction of CNO but do slow crystallization and lengthen induction time. The influence of sorbitan monolaurate, the only SE with an acyl group similar to that of CNO, is shown to depend on the crystallization temperature. At temperatures below its melting point, it only affects CNO's high‐melting fraction; at temperatures above its melting point, crystallization of both fractions is extensively decelerated. The lack of influence in polymorphic behaviour by any SE confirms no alteration of subcell arrangement, suggesting a lack of complementarity with the crystallizing fat. Overall, these SEs significantly impact the crystallization kinetics of CNO; however, this largely depends on type and concentration.     

Composition and crystallization behavior of solvent-fractionated palm stearin

Palm stearin (PS) is an extensively used trans-free hardstock. Depending on process parameters, fractions with unique compositions, hardness, and solid fat content can be tailored toward specific applications. In this work, the composition and crystallization of PS fractionated with acetone at 30°C, 35°C, or 40°C into various liquid (LF) and solid (SF) fractions were investigated. After fractionation, iodine value (IV) of PS changed from 37 to values ranging from 24 to 51. The IV of the LF increased with a decrease in fractionation temperature whereas that of the SF (~24) was unaffected. The main fatty acids of all PS fractions were palmitic and oleic acids, with the LF having a lower palmitic acid but higher oleic acid content than the SF. LF and SF obtained at higher fractionation temperatures showed more rapid crystallization rates. Under the microscope, the LF fractionated at 30°C and 35°C consisted of spherulites whereas those fractionated at 40°C exhibited dendritic crystals. All SF consisted of spherulites comprised of large rod-like crystals. All samples existed as mixtures of β’ and β crystals. This study serves as the basis for the development of baking margarines and pastry shortenings using fractionated PS.     

Margarines Produced From Rice Bran Oil and Fractionated Palm Stearin and Their Characteristics During Storage

Rice bran oil (RBO) usage in Southeast Asia is increasing. The purpose of this study was to incorporate RBO in margarine as a replacement for common oils such as soybean oil. The physicochemical properties of blends of RBO and fractionated palm stearin (FPS) at eleven different weight ratios (from 0:100 to 100:0) were characterized. Results showed that fat blends with ratios of 10:90, 20:80, and 30:70 RBO:FPS were semisolid at ambient temperature, with solid fat contents and a crystal morphology similar to commercial margarine fats. Blends containing ≤30% RBO were made into margarines and compared against commercial margarine over 8 weeks of storage. The margarine with a 20:80 RBO:FPS fat phase was stable against coalescence and phase separation while demonstrating acceptable spreadability and whippability at ambient temperature. Fat crystals in this blend were in the β′ polymorph at all time points during storage, which is a desired characteristic in margarine. This study showed that RBO may be effectively used for margarine production.