Performance of ß-carotene-loaded nanostructured lipid carriers under dynamic in vitro digestion system: Influence of the emulsifier type.

A better understanding of how emulsifier type could differently influence the behavior of nanostructured lipid carriers (NLC) under the gastrointestinal digestion process, as well as at the cellular level, is of utmost importance for the NLC-based formulations' optimization and risk assessment in the food field. In this study, NLC composed by fully hydrogenated soybean and high-oleic sunflower oils were prepared using soy lecithin (NLC Lß) or Tween 80 (NLC Tß) as an emulsifier. ß-Carotene was entrapped within NLC developed as a promising strategy to overcome ß-carotene's low bioavailability and stability. The effect of emulsifier type on the digestibility of ß-carotene-loaded NLC was evaluated using an in vitro dynamic digestion model mimicking peristalsis motion. The influence of ß-carotene-loaded NLC on cell viability was assessed using Caco-2 cells in vitro. NLC Tß remained stable in the gastric compartment, presenting particle size (PS) similar to the initial NLC (PS: 245.68 and 218.18 nm, respectively), while NLC Lß showed lower stability (PS > 1000 nm) in stomach and duodenum phases. NLC Tß also provided high ß-carotene protection and delivery capacity (i.e., ß-carotene bioaccessibility increased 10-fold). Based on the results of digestion studies, NLC Tß has shown better physical stability during the passage through the in vitro dynamic gastrointestinal system than NLC Lß. Moreover, the developed NLC did not compromise cell viability up to 25 µg/mL of ß-carotene. Thus, the NLC developed proved to be a biocompatible structure and able to incorporate and protect ß-carotene for further food applications. PRACTICAL APPLICATION: The findings of this study hold significant implications for industrial applications in terms of developing nanostructured lipid carriers from natural raw materials widely available and used to produce other lipid-based products in the food industry, as an alternative to synthetic ones. In this respect, the ß-carotene-loaded NLC developed in this study would find a great industrial application in the food industry, which is in constant search to develop functional foods capable of increasing the bioavailability of bioactive compounds.

Incorporation of curcumin-loaded solid lipid nanoparticles into yogurt: Tribo-rheological properties and dynamic in vitro digestion.

The incorporation of nanostructures loaded with bioactive compounds into food matrices is a promising approach to develop new functional foods with improved nutritional, health profiles and good sensorial properties. The rheological and tribological properties of yogurt enriched with curcumin-loaded solid lipid nanoparticles (SLN) were evaluated. Also, the TCA solubility index, the bioaccessibility of curcumin and cell viability were assessed after dynamic in vitro digestion. The presence of SLN in yogurt did not affect its rheological properties; however, SLN addition increased the lubrication capability of yogurt. After in vitro digestion, yogurt with added SLN (yogurt_SLN) presented a lower TCA solubility index (22 %) than the plain yogurt (39 %). The bioaccessibility and stability of curcumin were statistically similar for yogurt_SLN (30 % and 42 %, respectively) and SLN alone (20 % and 39 %, respectively). Regarding cell viability results, the intestinal digesta filtrates of both controls (i.e., SLN alone and plain yogurt) did not affect significantly the cell viability, while the yogurt_SLN presented a possible cytotoxic effect at the concentrations tested. In general, the incorporation of SLN into yogurt seemed to promote the mouthfeel of the yogurt and did not adversely affect the bioaccessibility of curcumin. However, the interaction of SLN and yogurt matrix seemed to have a cytotoxic effect after in vitro digestion, which should be further investigated. Despite that, SLN has a high potential to be used as nanostructure in a functional food as a strategy to increase the bioactive compounds' bioaccessibility.

Evaluating the in vitro digestion of lipids rich in medium-chain fatty acids (MCFAs) using dynamic and static protocols.

Investigating the digestion of lipids is paramount for developing new lipid-based products. This work evaluated the gastrointestinal (GI) digestion of medium-chain fatty acids (MCFAs) rich lipids. The dynamic GI in vitro system was used to simulate gastric, duodenal, jejunal, and ileal GI tract portions. Results from the dynamic protocol were compared against static in vitro assays and GC analyses were conducted to assess the FA profile of FFA released during digestion. Caprylic and capric acids released during the gastric digestion of MCT oil varied from 61-63% and 36-38% of total esterified FA, respectively. Lauric acid was the most representative FFA released (31-54%) during the gastric digestion of coconut oil samples. It was observed that the gastric digestion phase plays a crucial role in the MCFA lipolysis and the lipase activity restricted the amount of free MCFA liberated during the GI digestion, resulting in incomplete lipids hydrolysis.

Emerging challenges in assessing bio-based nanosystems' behaviour under in vitro digestion focused on food applications - A critical view and future perspectives.

The current consumers' demand for high quality food products together with the growing awareness regarding the link between health and nutrition has led to the development of novel food products with added functionality. Such functionality can be modulated by adding bio-based nanosystems that can improve the bioaccessibility of bioactive compounds and facilitate nutrient absorption. However, these functional properties can be significantly affected by the adverse conditions (e.g., low pH, presence of enzymes, salts) of the gastrointestinal tract. As such, understanding the behaviour of such delivery systems under digestion conditions is of utmost importance and several analytical tools and in vitro digestion models have been used for this purpose. This review summarizes the latest updates on nanosystems' performance under in vitro digestion and provides critical insights related to important and complementary analytical tools (e.g., rheology, Raman spectroscopy, x-ray scattering) used to assess their performance throughout digestion. Furthermore, the most prominent and frequent challenges associated with such in vitro analyses are also described, together with the current trends regarding the development of in vitro digestion models and some considerations that should be undertaken for their validation. Efforts must be made towards developing reliable and standard in vitro digestion models that use sophisticated analytical techniques to further expand the knowledge regarding nanosystems' behaviour under in vitro digestion conditions.

Encapsulated Pine Bark Polyphenolic Extract during Gastrointestinal Digestion: Bioaccessibility, Bioactivity and Oxidative Stress Prevention.

Polyphenolic extracts from pine bark have reported different biological actions and promising beneficial effects on human health. However, its susceptibility to environmental stresses (temperature, storage, etc.) and physiological human conditions prequires the development of efficient protection mechanisms to allow effective delivering of functionality. The aim of this work was to encapsulate pine bark extract rich phenolic compounds by spray-drying using maltodextrin, and understand the influence of encapsulation on the antioxidant and antimicrobial activity and bioaccessibility of phenolic compounds during gastrointestinal digestion. The optimized process conditions allowed good encapsulation efficiency of antioxidant phenolic compounds. The microencapsulation was effective in protecting those compounds during gastrointestinal conditions, controlling their delivery and enhancing its health benefits, decreasing the production of reactive oxygen species implicated in the process of oxidative stress associated with some pathologies. Finally, this encapsulation system was able to protect these extracts against acidic matrices, making the system suitable for the nutritional enrichment of fermented foods or fruit-based beverages, providing them antimicrobial protection, because the encapsulated extract was effective against Listeria innocua. Overall, the designed system allowed protecting and appropriately delivering the active compounds, and may find potential application as a natural preservative and/or antioxidant in food formulations or as bioactive ingredient with controlled delivery in pharmaceuticals or nutraceuticals.

Influence of the addition of different ingredients on the bioaccessibility of glucose released from rice during dynamic in vitro gastrointestinal digestion.

Rice represents a primary source of carbohydrates in human nutrition. Upon its consumption, the released sugars are mostly absorbed, categorising rice as a high glycemic index food. Addition of ingredients is common practice when cooking rice, which may affect rice digestibility and influence nutrients absorption in the gastrointestinal (GI) tract, enabling a controlled glucose release. In this sense, rice formulations were submitted to a dynamic in vitro GI model, constituted by reactors that simulates peristalsis coupled to filtration membranes, to evaluate carbohydrates hydrolysis and bioaccessibility. Addition of quinoa and wholegrains reduced carbohydrates hydrolysis (i.e. 38.5 ± 5.08% and 57.98 ± 1.91%, respectively) and glucose bioaccessibility (i.e. 25.92 ± 5.70% and 42.56 ± 1.39%, respectively) when compared with brown rice (i.e. 63.86 ± 2.96% hydrolysed and 44.33 ± 1.88% absorbed). Addition of vegetables significantly decreased sample chewiness and resulted in superior hydrolysis (71.75 ± 7.44%) and glucose absorption (51.61 ± 6.25%).

In vitro adsorption of aflatoxin B1, ochratoxin A, and zearalenone by micronized grape stems and olive pomace in buffer solutions.

This work characterizes the adsorption of aflatoxin B1 (AFB1), ochratoxin A (OTA), and zearalenone (ZEN) by dry micronized olive pomace (OliPom) and grape stems (GrapStem). Their performance was compared with that of three other materials, activated carbon (ActCarb), bentonite (Bent), and a commercial product (ComProd). Experiments were conducted in vitro at several pH values using buffer solutions. For OTA and ZEA, the strongest adsorbent was ActCarb, with 5 mg/mL being sufficient to bind > 99% of all the mycotoxins. For AFB1, ComProd and Bent were the most effective adsorbents, as 0.5 mg/mL bound > 95% of this mycotoxin. Among the two agro by-products, GrapStem was the strongest binder, with 10 mg/mL being sufficient to bind at least 90% of all the mycotoxins (except OTA at pH 7). OliPom was the least efficient material, but at a concentration of 30 mg/mL, its performance was similar to GrapStem. Adsorption isotherms were calculated, and ActCarb showed the maximum adsorption capacity (Qmax), with values that ranged from 19 to 24 µg/mg for pH 2 and from 17 to 20 µg/mg for pH 7. ComProd, Bent, and GrapStem showed more similar Qmax between them (1.4-4.4 µg/mg for pH 2 and 0.5-4.8 µg/mg for pH 7).