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Palmitoleic acid shows a variety of beneficial properties to human health. In this study, enrichment of palmitoleic acid from sea buckthorn pulp oil by two-step solvent crystallization and molecular distillation was investigated. Sea buckthorn pulp oil was first converted to its corresponding mixed fatty acids (SPOMFs) containing 27.17% palmitoleic acid. Subsequently, the effects of various factors on crystallization (i.e., crystallization temperature, type of solvent, ratio of SPOMFs to solvent (w/v), crystallization time) and molecular distillation (distillation temperature) were assessed on a 5-g scale. It was found that optimal primary crystallization conditions were a 1:15 ratio of SPOMFs to methanol (w/v), -20°C and 12 h. Secondary crystallization conditions were set to a 1:4 ratio of methanol to palmitoleic acid product obtained from the first step crystallization to methanol (w/v), -40°C and 6 h. For further purification of palmitoleic acid by molecular distillation, the optimal distillation temperature was determined to be 100°C. After purification by crystallization and molecular distillation under the optimal conditions, the final product consisted of 54.18% palmitoleic acid with an overall yield of 56.31%. This method has great potential for adoption by the food and medical industries for the preparation of palmitoleic acid concentrate for nutritional studies.

Trachinotus ovatus (TO) is an important cultured marine fish, which is popular with customers for its high muscle quality and favorable price. In this study, lipids in viscera, bone and muscle of TO were extracted and analyzed to identify unique applications. Total lipid content based on dry mass was 34.50% in muscle, 46.25% in bone, and 64.35% in viscera. In the lipid composition of TO oil (TOO), the contents of free fatty acids, diglycerides and phospholipids ranged from 3.54% to 7.21%, 1.88%–4.66% and 4.91%–6.35%, respectively. Phospholipids were mainly composed of phosphatidylcholine and phosphatidylethanolamine. Triglycerides were the major component in TOO for all tissues, the content range was 83.16%–89.39%. The main fatty acids of triglyceride fraction in TOO were palmitic acid (~24%), oleic acid (~26%), and linoleic acid (~26%). It is interesting to observe that palmitic acid was preferentially distributed at the sn-2 position. Ultra-high performance combined-phase chromatography combined with quadrupole time-of-flight mass spectrometry analysis showed that 1-oleoyl-2-palmitoyl-3-linoleoylglycerol was the highest content of triglyceride molecule in TOO, accounting for about 17%, followed by 1,3-dioleoyl-2-palmitoylglycerol. These unique composition and positional distribution in TOO are very similar to those of human milk fat. Therefore, TOO has a great potential in the preparation of human milk fat substitutes.

Most natural oils are low in n-3 polyunsaturated fatty acids (n-3 PUFAs) content, which limits their application in health products. In this study, n-3 PUFAs in glyceride form were selectively enriched by lipase-mediated hydrolysis of n-3 PUFA-containing oils. First, commercial lipases were screened, and the lipase AY “Amano” 400SD from Candida cylindracea was the best choice in producing n-3 PUFA glycerides from tuna oil. Subsequently, the hydrolysis conditions were optimized. Under the optimal conditions, the highest n-3 PUFA content in the glyceride fraction was found to be 57.7% after enzymatic hydrolysis. Addition of Ca2+ to the system significantly shortened the reaction time from 10 to 4 h. When algal oil was used as substrate, total PUFA contents in the glyceride fraction were 89.9%. This study provides an efficient enzymatic process to produce n-3 PUFA-enriched glyceride concentrates and demonstrates that AY “Amano” 400SD can effectively discriminate against n-3 PUFAs during hydrolysis.

In this study, a human milk fat substitute (HMFS) rich in 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) was prepared by physical blending. First, OPL was enzymatically synthesized by the acidolysis of fractionated palm stearin with oleic and linoleic acids. The reaction parameters were assessed until an optimum process was achieved. Under optimum conditions, contents of OPL and sn-2 palmitic acid in the synthesized OPL product were 47.93% and 87.90%, respectively. Subsequently, a physical blending model was established for the first time to prepare the HMFS similar to human milk fat (HMF). The optimum ratio of soybean oil, rapeseed oil, coconut oil, basa catfish oil and OPL product was determined to be 11.06%:2.91%:14.41%:35.02%:36.59%. The similarity between HMFS and HMF was evaluated by “deducting score” principle and the overall score of the HMFS was 84.98. The prepared HMFS have higher similarity than commercial HMFS products and thus are potential to be used in infant formulas.

Foaming of frying oil has troubled the production but not yet systematically explained. In this research, individual and combined effects of 16 process, chemical and physical parameters of frying oil were tested. Prepared oil samples with different deterioration levels were further physically blended to avoid the interference of colinearity. A new integrated index to describe the Molecular Weight Disparity (MWD) was proposed and proved to be well correlated with both deterioration and foaming of oil (r = 0.845 ~ 0.997, p 0.05). Effects of all indices except the peroxide value, anisidine value, total oxidation value and surface tension of oil were significant (p 0.05) and their combined effect was presented by equations (p 0.05). The effect of frying load was approximately 1.3 times higher than that of oil deterioration. Data will be helpful to seek efficient oil formulation and achieve intelligent control of industrial production.

1-Oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) is a critical structured lipid in human milk fat and it plays an important role in infants' health. The development of an efficient method for such compound preparation is necessary. In this study, one- and two-step methods for OPL production by enzymatic acidolysis of fractionated palm stearin with mixed acids were compared in solvent-free and solvent systems. The results demonstrated that in the solvent system, the OPL contents by the one- and two-step methods were 45.8% and 56.7%, respectively. In the solvent-free system, the one- and two-step methods resulted in the formation of 43.7% and 54.8% OPL, respectively. Subsequently, acidolysis conditions of the two-step method were optimized. Under the optimum conditions, the content of OPL was 57.7%, and 83.2% of palmitic acid was at the sn-2 position. The prepared OPL has potential to be applied in infant formulas.