Preparation of beta-carotene nanoemulsion and evaluation of stability at a long storage period

Abstract Carotenoids have a low solubility in water, and therefore their incorporation in foods is impaired. The nanoemulsions are able to protect these compounds and enhance bioavailability. The objective of this study was to develop nanoemulsions with added beta-carotene, evaluating the influence of process variables and the stability at a long storage period. To assess the effects of these variables a Box-Behnken design was performed. The best condition to form a stable emulsion was 7% (w.w-1) of surfactant and 40 °C. All formulations subjected to a thermal stress test remained stable after the test. The use of a higher concentration of soy lecithin (7%, w.w-1) in the development of emulsions conferred greater stability after a freeze-defrost cycle. Furthermore, with this concentration of surfactant, and using a high-speed homogenizer under conditions of 10,000 rpm, 30 °C, and 20 min of shaking time, it was possible to develop stable nanoemulsion with an average diameter of 429 nm. Moreover, the zeta potential indicated system stability. Thus, it was possible to obtain stable nanoemulsion without the use of subsequent equipment, which makes the process less expensive.

摘要：类胡萝卜素（Carotenoids）在水中的溶解度极低，因此其在食品中的添加应用受到限制。纳米乳液（nanoemulsions）可对这类化合物起到保护作用，并提升其生物利用度。本研究旨在制备添加β-胡萝卜素的纳米乳液，考察工艺变量对体系的影响以及长期储存过程中的稳定性。为评估上述变量的作用效果，本研究采用了Box-Behnken试验设计（Box-Behnken design）。结果表明，制备稳定乳液的最优工艺条件为：表面活性剂（surfactant）用量7%（w·w⁻¹），制备温度40℃。所有经热应力测试的配方在测试后均保持稳定。采用7%（w·w⁻¹）的大豆卵磷脂（soy lecithin）制备乳液，可使体系在冻融循环后拥有更优的稳定性。此外，采用该表面活性剂浓度，结合高速均质机（high-speed homogenizer），在10000 rpm、30℃、均质20分钟的条件下，可制备得到平均粒径为429 nm的稳定纳米乳液。Zeta电位（zeta potential）检测结果证实了体系的稳定性。综上，无需额外后续设备即可获得稳定的纳米乳液，有效降低了工艺成本。