Effect of production parameters and stress conditions on beta-carotene-loaded lipid particles produced with palm stearin and whey protein isolate

Abstract Microencapsulation is currently used by the food industry for different purposes, including the protection of ingredients against factors such as oxidation and volatilization, as well as to increase the bioavailability and bioaccessibility of nutrients. The current study aimed to encapsulate beta-carotene in solid lipid microparticles stabilized with whey protein isolate (WPI), and also investigate their integrity during storage and under stress conditions such as different ionic strengths, sucrose concentrations and thermal treatments. Solid lipid microparticles were produced using palm stearin, a food grade vegetable fat, using a single-step high shear process. Of the different formulations used for lipid microparticle production, characterization studies showed that the greatest stability was obtained with systems produced using 1.25% (w/v) whey protein isolate, 5% (w/v) palm stearin and 0.2% (w/v) xanthan gum. This formulation was applied for the production of beta-carotene-loaded solid lipid microparticles, with different concentrations of alpha-tocopherol, in order to verify its possible antioxidant activity. The results showed that the addition of alpha-tocopherol to the dispersions provided an increase in encapsulation efficiency after 40 days of storage that ranged from 29.4% to 30.8% when compared to the system without it. Furthermore, the solid lipid microparticles remained stable even when submitted to high ionic strength and to heating in the proposed temperature range (40 °C to 80 °C), highlighting their feasible application under typical food processing conditions.

摘要：微囊化技术（microencapsulation）目前已广泛应用于食品工业的多个场景，可用于保护活性成分免受氧化、挥发等不利因素侵害，同时提升营养素的生物利用率与生物可及性。本研究旨在以乳清分离蛋白（whey protein isolate, WPI）稳定固体脂质微粒（solid lipid microparticles），将β-胡萝卜素（beta-carotene）包埋于其中，并考察其在储存过程以及不同离子强度、蔗糖浓度、热处理等胁迫条件下的结构完整性。本研究采用单步高速剪切工艺，以食品级植物脂肪棕榈硬脂（palm stearin）为原料制备固体脂质微粒。在用于制备脂质微粒的多种配方中，表征分析结果显示，采用1.25%（w/v）乳清分离蛋白、5%（w/v）棕榈硬脂以及0.2%（w/v）黄原胶（xanthan gum）制备的体系稳定性最优。选取该最优配方制备负载不同浓度α-生育酚（alpha-tocopherol）的β-胡萝卜素固体脂质微粒，以验证α-生育酚的潜在抗氧化活性。结果表明，与未添加α-生育酚的体系相比，在分散液中加入α-生育酚后，储存40天的包埋效率提升幅度可达29.4%~30.8%。此外，该固体脂质微粒在高离子强度以及40℃~80℃的热处理条件下仍可保持稳定，这表明其在典型食品加工场景中具备可行的应用潜力。