Candida antartica lipase-catalyzed esterification for efficient partial acylglycerol synthesis in solvent-free system: Substrate selectivity, molecular modelling and optimization.

Partial acylglycerols are valued for their emulsifying and stabilizing properties, yet precise green synthesis remains challenging due to low yield and selectivity. This study aimed to elucidate the "lipase selectivity-substrate structure-product composition" relationship to enhance the yield of targeted partial acylglycerol. The results showed that lipase exhibited a greater selectivity towards fatty acids with shorter chain lengths and higher unsaturation. Hydroxyl donors also affected the esterification process, with the enzyme-acyl complex exhibiting selectivity towards hydroxyl donors as follows: glycerol > monoacylglycerol > diacylglycerol. Substrate ratio significantly influenced enzymatic reactions; a 10:1 ratio favored triacylglycerol formation (>80 %), while a 1:1 ratio produced > 90 % partial acylglycerols. Molecular docking simulations revealed that substrates primarily interacted with lipase through hydrogen bonding and hydrophobic interactions. A comprehensive understanding of lipase selectivity patterns could facilitate the design of more efficient reaction systems, enabling the conversion of basic lipid resources into desired high value-added products.

Effect of diacylglycerol on partial coalescence of aerated emulsions: Fat crystal-membrane interaction and air-liquid Interface interaction insights.

Currently, the poor whipping capabilities of anhydrous milk fat (AMF) in aerated emulsion products are a major obstacle for their use in beverages like tea and coffee, as well as in cakes and desserts, presenting fresh hurdles for the food industry. In this study, the mechanism of action of diacylglycerols (DAGs) with different carbon chain lengths and degrees of saturation on the partial coalescence of aerated emulsions was systematically investigated from three fundamental perspectives: fat crystallization, air-liquid interface rheology, and fat globule interface properties. The optimized crystallization of long carbon chain length diacylglycerol (LCD) based on stearate enhances interactions between fat globules at the air-liquid interface (with an elastic modulus E' reaching 246.42 mN/m), leading to a significantly reduced interface membrane strength. This promotes fat crystal-membrane interactions during whipping, resulting in a thermally stable foam structure with excellent shaping capability due to enhanced partial coalescence of fat globules. Although Laurate based medium carbon chain length diacylglycerol (MCD) promoted fat crystallization and optimized interface properties, it showed weaker foam properties because it did not adequately encapsulate air bubbles during whipping. Conversely, oleate long carbon chain length diacylglycerol (OCD) proved to be ineffective in facilitating fat crystal-membrane interaction, causing foam to have a subpar appearance. Hence, drawing from the carefully examined fat crystal-membrane interaction findings, a proposed mechanism sheds light on how DAGs impact the whipping abilities of aerated emulsions. This mechanism serves as a blueprint for creating aerated emulsions with superior whipping capabilities and foam systems that are resistant to heat.

Texture and volatile profiles of beef tallow substitute produced by a pilot-scale continuous enzymatic interesterification.

Edible beef tallow (BT) has been widely used in Sichuan hotpot due to its unique flavor and texture. However, BT should not be consumed in excess caused by its trans-fatty acids and cholesterol issues. In this study, a BT substitute was prepared after enzymatic interesterification in a pilot-scale packed-bed reactor using soybean oil and fully hydrogenated palm oil (4:3, w/w) as feedstock. The products were characterized against BT in terms of fatty acid/triacylglycerol compositions, solid fat content, polymorphism, and melting/crystallization behaviors to select the most promising BT substitute. The optimal flow rate was 120 mL/min. Changes in volatile compounds during stir-frying and simmering were also investigated for Sichuan hotpots made with these two oils. The volatile compounds of BT substitute were similar to that of natural BT. The findings will contribute to expanding the base oil categories of Sichuan hotpot oils.

Effect of palm stearin on the physicochemical characterization and capsaicinoid digestion of Sichuan hotpot oil.

Beef tallow (BT) is the common hotpot oil used in Sichuan hotpot, increasing its characteristic flavors and making it taste better. However, the cholesterol content in BT is high, which may induce cardiovascular diseases. In this study, the effect of palm stearin (PS) on Sichuan hotpot oil was evaluated. The PS: BT blends showed similar physicochemical properties to BT from the results of sensory evaluation, pulsed NMR, DSC, and polar light micrograph (PLM). Furthermore, since spiciness is the essential characteristic of Sichuan hotpot, the digestive properties of capsaicinoids in hotpot oil were used as an evaluation index. The results showed that the digestive properties of capsaicinoids in hotpot oil containing PS were consistent with those without PS. In conclusion, PS can be partially used to replace BT, which can broaden the types of oil used for hotpot and help develop a new hotpot oil.

Enzymatic preparation of structured triacylglycerols with arachidonic and palmitic acids at the sn-2 position for infant formula use.

Structured TAGs with palmitic acid and polyunsaturated fatty acid (PUFA) at the sn-2 position have various health benefits for infants. In this study, we first compared two enzymatic routes for preparation of the structured TAGs. Results showed that the one-pot and two-step syntheses led to 37.6% and 55.4% oleic acid incorporation, respectively, after 10 h and reaction route had little effect on the sn-2 fatty acid composition. Subsequently, reaction variables of the two-step synthesis were optimized. Under the optimal conditions, 53.5% oleic acid was incorporated into the structured TAGs after 6-h acidolysis. Major fatty acids at the sn-2 position were palmitic acid (68.7%), ARA (9.8%) and oleic acid (7.9%). This is the first study reporting a two-step enzymatic method for structured TAGs preparation. Compared to the one-pot synthesis, current method significantly improves the efficiency of the acidolysis by product inhibition elimination. The synthetic TAGs have potential use in infant formulas.

Towards a model of the mineral-organic interface in bone: NMR of the structure of synthetic glycosaminoglycan- and polyaspartate-calcium phosphate composites.

We have synthesised three materials-chondroitin sulphate (ChS, a commercial product derived from shark cartilage and predominantly chondroitin-6-sulphate (Ch-6-S)) bound to pre-formed hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)), HA formed in the presence of ChS and poly-Asp bound to pre-formed HA-to generate models for the mineral-organic interface in bone. The three materials have been investigated by (13)C cross polarisation magic-angle spinning (CPMAS) NMR, (13)C{(31)P} rotational echo double resonance (REDOR) and powder x-ray diffraction (XRD) in order to verify their composition and to determine the nature of their binding to HA. Our results show that for HA formed in the presence of Ch-6-S, all carbon atoms in the Ch-6-S having contact with mineral phosphate. We propose that HA in this case forms all around the Ch-6-S polymer rather than along one face of it as is more commonly supposed in cases of templating by organic molecules. However, Ch-6-S binding to pre-formed HA probably occurs via a surface layer of water on the mineral rather than to the mineral directly. In contrast, poly-Asp binds closely to the pre-formed HA surface and so is clearly able to displace at least some of the surface-bound water.

Synthesis and concentration of 2-monoacylglycerols rich in polyunsaturated fatty acids.

Polyunsaturated fatty acids (PUFA) in 2-monoacylglycerols form exhibit various biological activities and have potential applications in food and pharmaceuticals. Preparation of 2-monoacylglycerols was conducted by enzymatic enthanolysis. The effects of lipase type, substrate weight ratio, reaction time and lipase load on the 2-monoacylglycerols content in the crude product were investigated. Lipozyme 435 behaved as 1,3-specific and high-catalytic-activity lipase in this reaction. Under the optimal conditions (ethanol:oil = 3:1 (w/w), 8% Lipozyme 435, 3 h), 27% 2-monoacylglycerols were obtained. After solvent extraction of 2-monoacylglycerols, the abilities of low temperature crystallization and molecular distillation to concentrate 2-PUFA-monoacylglycerols were compared. Low temperature crystallization concentrated 81.13% and 74.29% PUFA by acetonitrile and hexane, respectively, with over 90% in 2-monoacylglycerol forms. Conversely, molecular distillation yielded a PUFA concentration of 72% but decreased the 2-monoacylglycerols content to 69.81%. Thus, the method including enzymatic ethanolysis and low temperature crystallization is suitable for preparation of 2-monoacylglycerols rich in PUFA.

Synthesis of 2-docosahexaenoylglycerol by enzymatic ethanolysis.

Synthesis of 2-docosahexaenoylglycerol with high nutritional value was conducted by enzymatic ethanolysis of algal oil. The effects of lipase type, substrate molar ratio of algal oil to ethanol, reaction time, reaction temperature and lipase load on the content of 2-monoacylglycerols (2-MAGs) in the crude product were investigated. Under the optimal conditions, 27-31% 2-MAGs were obtained in the ethanolysis reaction. Lipozyme 435 exhibited 1,3-specific selectivity and maintained stable operational stability after 7 successive reuse cycles. The enzymatic ethanolysis catalyzed by Lipozyme 435 could both synthesize 2-MAGs and concentrate DHA. Further purification of 2-MAGs was performed with solvent extraction by 85% ethanol aqueous solution and hexane, obtaining 95% 2-MAGs in a yield of 67%. The contents of DHA in 2-MAGs product and 2-MAGs fraction were 74.76% and 75.66%, respectively, which were about 26% higher than that in the algal oil. Therefore, this method is efficient and environmental-friendly for synthesis of 2-docosahexaenoylgylcerol.

Crystal imperfection studies of pure and silicon substituted hydroxyapatite using Raman and XRD.

Hydroxyapatite (HA) is important in biomedical applications because of its chemical similarity to the mineral content of bone and its consequent bioactivity. Silicon substitution into the hydroxyapatite crystal lattice was found to enhance its bioactivity both in vitro and in vivo [1, 2]. However, the mechanism for the enhancement is still not well understood. In this paper, the crystal imperfections introduced by silicon substitution were studied using XRD and Raman spectroscopy. It was found that silicon substitution did not introduce microstrain, but deceased the crystal size in the hk0 direction. Three new vibration modes and peak broadening were observed in Raman spectra following silicon incorporation. The imperfections introduced by silicon substitution may play a role in enhancing bioactivity. A phenomenological relationship between the width of the PO4 v1 peak and crystal size was established.