Biophysical Aspects of Lipid Digestion in Human Breast Milk and Similac™ Infant Formulas

Bioaccessibility of avocado polyhydroxylated fatty alcohols

Avocado-derived polyhydroxylated fatty alcohols (PFAs), such as avocadene and avocadyne, have been recently identified as potent modulators of mitochondrial metabolism which selectively induce leukemia cell death and reverse pathologies associated with diet-induced obesity. However, avocadene and avocadyne bioaccessibility from avocado pulp is not reported; hence, this study aims to investigate if these PFAs are bioaccessible. Dynamic (TNO dynamic intestinal model-1 (TIM-1)) and static in vitro digestion of lyophilized Hass avocado pulp powder shows lipolytic gastrointestinal enzymes led to appreciable bioaccessibility of avocadene (55%) and avocadyne (50%). Furthermore, TIM-1 digestion of a 1:1 ratio of pure avocadene and avocadyne (avocatin B or AvoB) crystals formulated in an oil-in-water microemulsion has on average 15% higher bioaccessibility than the avocado pulp powder demonstrating both dosage forms as potential dietary sources of avocado PFAs. This research provides the impetus for further research on the nutritional significance of dietary long chain fatty alcohols.

Fat globule diameter in infant formulas

OBJECTIVES

The lipid fraction, fatty acid profile, and diameter of fat globules of infant formulas show great differences from human milk. These characteristics influence fat digestion and, consequently, the development and health of infants. The aim of this study was to evaluate the diameter of fat globules in infant formulas and compare them with those in human milk.

METHODS

The diameter of fat globules of 10 infant formulas and human milk samples was determined using scanning electron microscopy.

RESULTS

The starter infant formula was the only one that showed a mean diameter value (3.52 ± 2.17 µm) similar to that obtained for human milk (3.44 ± 1.68 µm). The starter infant formula showed the highest values of volume-surface D3,2 (6.13 µm) and volume-weighted D4,3, (7.05 µm) mean diameters among the infant formulas analyzed, and close to those obtained for the human milk sample (5.16 and 5.98 µm, respectively). The infant formulas whey protein partially hydrolyzed, soy protein isolate-based, whey protein extensively hydrolyzed, and thickened with pregelatinized starch had the lowest mean diameters of fat globules 0.64 ± 0.22, 0.70 ± 0.19, 1.06 ± 0.34, and 1.22 ± 0.48 µm, respectively.

CONCLUSION

The analysis of principal components showed that none of the analyzed infant formulas had similarity with the diameter of fat globules and the fatty acid profile of human milk.

Comparison of phospholipid composition and microstructure of milk fat globules contained in human milk and infant formulae

Phospholipids play key roles in infant nutrition and cognitive development. It is hypothesized that infant formula (IF) has lower phospholipid species, content and milk fat globule (MFG) structural integrity than human milk (HM). Herein, we performed qualitative and quantitative analyses of phospholipids in six classes of IF and HM using ultra-performance liquid chromatography with mass spectrometry. The contents of phosphatidylethanolamine (15.81 ± 7.20 mg/L) and sphingomyelin (35.84 ± 15.56 mg/L) in IF were significantly lower than those in HM (30.74 ± 17.38 mg/L, 45.53 ± 16.04 mg/L, respectively). Among the six IF classes, cow's milk-based IF had the highest number of phospholipid species, and IF containing milk fat globular membrane had the highest phospholipid content. The size, zeta potential, and amount of MFGs in IF were significantly lower than those in HM. These results may prove useful for designing better IF that mimic HM.

Interfacial composition in infant formulas powder modulate lipid digestion in simulated in-vitro infant gastrointestinal digestion

The interface structure and composition of fat globules are very important for the digestion and metabolism of fat and growth in infants. Interface composition of fat globules in infant formula (IF) supplemented with milk fat globule membranes (MFGM) and lecithin in different ways were analyzed and their effects on fat digestion properties were evaluated. The results showed that the distribution of phospholipids at the interface and structural of Concept IF1 and Concept IF2 that were more similar to those of human milk (HM) than that of conventionally processed IF3. Concept IF2 and IF3 supplemented with lecithin had larger initial particle size and more sphingomyelin (SM) (23.12 ± 0.26 %, 26.94 ± 0.34 %) than Concept IF1, and Concept IF2 had the smallest proportion of casein in the interfacial. Due to its interface composition, Concept IF2 had the highest degree of lipolysis (85.07 ± 0.76 %), the phospholipid ring structure can always be observed during gastric digestion, and a final fatty acid composition released that was more similar to HM. Concept IF1 and IF3 were different from HM and Concept IF2 in terms of structure and lipolysis rate, although superior to commercial IF4. These indicate that changes in the interfacial composition and structure of fat globules improve the digestive properties of fats in IF. Overall, the results reported herein are useful in designing new milk formulas that better simulate HM.

The influence of MPL addition on structure, interfacial compositions and physicochemical properties on infant formula fat globules

The lack of milk fat globule membrane phospholipids (MPL) at the interface of infant formula fat globules has an impact on the stability of fat globules, compared to human milk. Therefore, infant formula powders with different MPL contents (0%, 10%, 20%, 40%, 80%, w/w of MPL/whey protein mixture) were prepared, and the effect of interfacial compositions on the stability of globules was investigated. With increasing MPL amount, the particle size distribution had two peaks and returned to a uniform state when 80% MPL was added. At this composition, the MPL at the oil-water interface formed a continuous thin layer. Moreover, the addition of MPL improved the electronegativity and the emulsion stability. In terms of the rheological properties, increasing the concentration of MPL improved the elastic properties of the emulsion and the physical stability of the fat globules, while reducing the aggregation and agglomeration between fat globules. However, the potential for oxidation increased. Based on these results, the interfacial properties and stability on infant formula fat globules was significantly influenced by the level of MPL, which should be considered in the design of infant milk powders.

Human milk microbiota: what did we learn in the last 20 years?

Human milk (HM) is the gold standard for infant nutrition during the first months of life. Beyond its nutritional components, its complex bioactive composition includes microorganisms, their metabolites, and oligosaccharides, which also contribute to gut colonization and immune system maturation. There is growing evidence of the beneficial effects of bacteria present in HM. However, current research presents limited data on the presence and functions of other organisms. The potential biological impacts on maternal and infant health outcomes, the factors contributing to milk microbes' variations, and the potential functions in the infant's gut remain unclear. This review provides a global overview of milk microbiota, what the actual knowledge is, and what the gaps and challenges are for the next years.

Roles of Milk Fat Globule Membrane on Fat Digestion and Infant Nutrition

Milk fats are present as globules emulsified in the aqueous phase of milk and stabilized by a delicate membrane architecture called milk fat globule membrane (MFGM). The unique structure and composition of the MFGM play an important role in fat digestion and the metabolic programming of neonates. The objective of this review is to compare the structure, composition, and physicochemical characteristics of fat globules in human milk, bovine milk, and infant formula. It provides an overview of the fat digestion process and enzymes in healthy infants, and describes the possible roles of the MFGM in association with factors affecting fat digestion. Lastly, the health benefits of the MFGM on infant nutrition and future perspectives are discussed with a focus on brain development, metabolic response, and gut health.

A Survey to Identify the Current Management of Cow’s Milk Disorders and the Role of Goat Milk-Based Formulas in the Middle East and North Africa Region

Background: Cow’s milk allergy (CMA) and cow’s milk intolerance (CMI) are the major cow’s milk disorders observed in infants and young children. This study investigates, for the first time, physician knowledge regarding CMA and CMI prevalence, diagnosis, and management in the Middle East and North Africa (MENA) region. In addition, we explore the role of goat milk-based formula as an alternative in infants suffering from CMI. Method: This cross-sectional survey was conducted from December 2020 to February 2021. A convenience sample of 2500 MENA-based physicians received the questionnaire, developed by a working group of pediatric experts. Results: 1868 physicians completed the questionnaire, including pediatric specialists (80.8%), training physicians (0.2%), dermatologists (0.1%), family/general physicians (12.9%), neonatologists (3.6%), neurosurgeons (0.2%), allergy nurse specialists (0.3%), pharmacists (2.1%), and public health workers (0.1%). Differentiation between CMA and CMI was recognized by the majority of respondents (80.7%), for which the majority of respondents (35.4%) identified that the elimination and challenge test was the best test to differentiate CMA from CMI, whereas 30.7% and 5.4% preferred the immunoglobulin E (IgE) test and skin prick test, respectively. In addition, 28.5% of respondents reported that there is no confirmatory test to differentiate CMA from CMI. The majority of respondents (47.3%) reported that amino acid-based formula (AAF)/ extensively hydrolyzed formula (EHF) is the cornerstone for the management of CMA. However, most respondents (33.7%) reported that lactose avoidance was best for the management of CMI. Overall, 65% of the respondents were aware of nutritionally adapted goat’s milk formula as an alternative to cow’s milk products and 37% would recommend its routine use in infants (≤2 years of age). Conclusion: The results of this survey demonstrate that the majority of physicians are aware of the underlying pathophysiology and management of CMA and CMI. However, a significant proportion of physicians do not follow the clinical guidelines concerning CMA/CMI diagnosis and management. Notably, this survey identified that goat’s milk formulas may offer a suitable alternative to AAF/EHF in infants with CMI as they contain β-casein protein which is easily digestible. In addition, goat’s milk formulas contain higher levels of oligosaccharides and medium-chained fatty acids compared with standard cow’s milk formulas, yet further clinical trials are warranted to support the inclusion of goat’s milk formulas in clinical guidelines.

A Comparative Analysis of Lipid Digestion in Human Milk and Infant Formulas Based on Simulated In Vitro Infant Gastrointestinal Digestion

To investigate the lipid digestive behaviors of human and infant formulas and analyze the differences between them, we investigated the fat globule particle size distribution, lipolysis rate, and fatty acid release of infant formulas with different fat sources and human milk using an in vitro infant digestion model. The results suggested that the particle size in infant formula increased rapidly during gastric digestion and decreased significantly after intestinal digestion, whereas the particle size in human milk increased slowly during gastric digestion but increased rapidly during intestinal digestion (p < 0.05). Despite having a larger droplet size, human milk demonstrated a very high lipolysis rate due to the presence of MFGM. In terms of the distribution of fatty acids in digestion products, the proportion of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) in vegetable oil-based infant formulas was close to that of human milk. The amount of SFAs in milk fat-based infant formulas was significantly higher than that in human milk, and the content of MUFAs in all infant formulas was significantly lower than that in human milk (p < 0.05). After digestion, the most abundant fatty acid released by human milk was C18:2n6c, while the fatty acids released by infant formulas were SFAs, such as C14:0, C16:0, and C18:0.

Compositional, Structural, and Kinetic Aspects of Lipid Digestion and Bioavailability: In Vitro, In Vivo, and Modeling Approaches

Lipid digestion and bioavailability are usually investigated separately, using different approaches (in vitro, modeling, in vivo). However, a few inclusive studies show that their kinetics are closely linked. Lipid bioavailability kinetics is likely involved in the development and evolution of several diseases, so lipid digestion kinetics could be involved as well and can be modulated by food design or combination. To illustrate this possibility, the compositional and structural aspects of lipid digestion kinetics, as investigated using in vitro and modeling approaches, are presented first. Then, in vivo and mixed approaches enabling the study of both kinetics are reviewed and discussed. Finally, disparate modeling approaches are introduced, and a unifying modeling scheme is proposed, opening new perspectives for understanding the role and interactions of various factors (chemical, physical, and biological) involved in lipid metabolism.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Compositional and Functional Considerations for Bovine-, Caprine- and Plant-Based Infant Formulas

Breastmilk is the optimal source of nutrition for infants. However, in circumstances where breastfeeding is not possible or feasible, infant formula provides an essential alternative to fulfil the nutritional requirements of the developing infant. Traditionally, the manufacture of infant formula has involved utilisation of bovine milk as a base ingredient, formulated with other nutrients and bioactive ingredients to closely match the composition of human breastmilk. While it is the most widely available type of formula on the market, bovine-based infant formula is not suitable for all infants, and therefore alternatives such as those based on caprine milk, soy and rice protein are becoming increasingly available. This review provides a detailed examination of the composition of infant formula prepared from bovine milk, caprine milk, soy, and rice protein sources. Available literature on nutrient bio-accessibility and aspects of protein functionality relevant to infant formula is discussed.

Comparative Analysis of Lipid Digestion Characteristics in Human, Bovine, and Caprine Milk Based on Simulated In Vitro Infant Gastrointestinal Digestion

Lipid digestion characteristics in human, bovine, and caprine milk were investigated using an infant in vitro digestion model. Our results suggested that particle size in bovine and caprine milk increased initially and then decreased over time, whereas the particle size in human milk continuously decreased. The lipolysis degree of human milk (86.8%) was higher than that in bovine (80.2%) and caprine (82.7%) milk (P < 0.05). Compared to human milk, bovine and caprine milk released higher unsaturated fatty acids and lower SFAs. In addition, 12 and 84 glyceride species were significantly different between bovine and human milk, during gastrointestinal digestion (P < 0.05). Another 13 and 92 glyceride species were found to be significantly different between caprine and human milk. A total of 30 and 31 lipids were screened as biomarkers to further clarify the differences related to lipid digestion properties of human, bovine, and caprine milk.

In vitro models of gut digestion across childhood: current developments, challenges and future trends

The human digestion is a multi-step and multi-compartment process essential for human health, at the heart of many issues raised by academics, the medical world and industrials from the food, nutrition and pharma fields. In the first years of life, major dietary changes occur and are concomitant with an evolution of the whole child digestive tract anatomy and physiology, including colonization of gut microbiota. All these phenomena are influenced by child exposure to environmental compounds, such as drugs (especially antibiotics) and food pollutants, but also childhood infections. Due to obvious ethical, regulatory and technical limitations, in vivo approaches in animal and human are more and more restricted to favor complementary in vitro approaches. This review summarizes current knowledge on the evolution of child gut physiology from birth to 3 years old regarding physicochemical, mechanical and microbial parameters. Then, all the available in vitro models of the child digestive tract are described, ranging from the simplest static mono-compartmental systems to the most sophisticated dynamic and multi-compartmental models, and mimicking from the oral phase to the colon compartment. Lastly, we detail the main applications of child gut models in nutritional, pharmaceutical and microbiological studies and discuss the limitations and challenges facing this field of research.

Simulated In Vitro Infant Gastrointestinal Digestion of Infant Formulas Containing Different Fat Sources and Human Milk: Differences in Lipid Profiling and Free Fatty Acid Release

Simulated in vitro infant gastrointestinal digestion of human milk and four infant formulas containing different fat sources was analyzed and compared in this study. Although there are disadvantages brought about by its larger droplet size than infant formulas, human milk exhibited a higher lipolysis level due to the presence of MFGM interfacial layers. Higher hydrolysis efficiency of infant formulas (IFB, IFC, and IFM) was due to the presence of MFGM/phospholipid-enriched materials. Human milk released higher free fatty acid levels, especially long-chain fatty acid, and less undigested TAG molecules at the end of digestion than infant formulas. Human milk had a higher proportion of MAG and DAG linked to long-chain fatty acid. Furthermore, several lipids were identified as potential biomarkers that could be used to further analyze differences in the biological properties of human, bovine, and caprine milk. This comprehensive analysis might be fruitful to formulate an infant formula closest to human milk.

Fluid-structure interaction modeling of lactating breast: Newtonian vs. non-Newtonian milk

Breastfeeding is a highly dynamic and complex mechanism. The suckling process by the infant involves compression and intra-oral vacuum pressure, leading to milk expression from breast. The accumulated milk from the nipple varies depending on the milk properties and transient flow rate during the suckling cycle. Rheological studies on raw human milk indicate that milk has a non-Newtonian shear-thinning flow behavior. This study aims to investigate the effect of non-Newtonian milk on flow behavior through the breast ductal system using fluid-structure interaction (FSI) simulation. The results of the non-Newtonian effects on flow velocity and the volumetric flow rate of expressed milk are presented. The results show that non-Newtonian Carreau model is promising for the simulation of human milk flow through the breast ductal systems. Also, the results show that the non-Newtonian effects on the milk flow behavior appear for 30-35% of the suckling cycle. Therefore, the Newtonian model is acceptable for the purpose of numerical simulation.

Gastric protein digestion of goat and cow milk infant formula and human milk under simulated infant conditions

The protein digestion kinetics of goat milk infant formula (GMF) is previously shown to be more comparable to that of human milk (HM) than cow milk infant formula (CMF). To evaluate whether gastric behaviour contributes to differences in protein digestion kinetics, fresh HM, a GMF and a CMF were subjected to in vitro gastric digestion simulating infant conditions. Coagulation behaviour, particle size distribution and viscosity of the digesta were evaluated. After centrifugation of the digesta, total solids and protein distribution, and protein hydrolysis in the cream, serum and pellet fraction were investigated. The GMF and CMF were in general similar with respect to physicochemical and protein breakdown properties. However, a number of notable differences in physicochemical behaviour were observed, which may contribute to faster initial protein digestion of GMF. HM behaved differently from both formulas. These differences provide new insights into the possibilities for improvement of infant formulas.

Correlations of Fat Content in Human Milk with Fat Droplet Size and Phospholipid Species

Fat globule size and phospholipid (PL) content in human milk (HM) were investigated. HM was classified into three groups depending on fat content (A < B < C). PL content (mg/100 g HM) was significantly higher in the C group (p < 0.05), indicating its positive relationship with HM fat content. When the PL content was normalized (mg/g fat), that of group A was significantly higher (p < 0.05) and fat droplet size in group C was slightly larger, suggesting that HM fat content is affected by fat droplet numbers to a larger extent than by fat droplet size. A correlation between PC and SM content in HM was observed regardless of fat content, while correlation between PE and either PC or SM increased in the order of C > B > A, hence the composition and content of PL species in HM varied according to its fat content.

Evidence from Neonatal Piglets Shows How Infant Formula and Other Mammalian Milk Shape Lipid Metabolism

We tested the hypothesis that the consumption of different milk lipids is one of the factors affecting metabolic response to lipid in the early life of infants. Neonatal piglets, as animal models, were stratified by the feeding mode (formula-fed, bovine-, caprine-, and human milk-fed). Lipidomic profiles of plasma and liver samples were detected using liquid chromatography-mass spectrometry (LC-MS). The results indicate that 31, 54, and 28 differential lipid species could be used as potential biomarkers for bovine milk, caprine milk, and infant formula-fed samples, respectively, and the main lipid classes screened in plasma were SM, PC, and PE, including PC(14:1/P-20:0) as the isoform of PC(34:1), which regulates the lipid metabolism gene peroxisome proliferator-activated receptor α, PPAR-α. SM(d15:1/22:0) was the common potential biomarker screened from all of the groups. The amounts of biomarkers screened from the caprine milk-fed liver samples were the highest, which had a significant effect on the distribution of SM, PI, and PA. Infant formula, bovine-, and caprine milk-fed samples had an obvious effect on the metabolism of glycerophospholipid and glycerol ester, especially TG (16:0/18:0/18:2).

Effect of Particle Size and Interface Composition on the Lipid Digestion of Droplets Covered with Membrane Phospholipids

The particle size and fatty acid release of droplets covered with milk fat globule membrane phospholipids with different particle sizes (large/MPL-L; medium/MPL-M; and small/MPL-S) and emulsions with different sources (droplets covered with MPL/MPLs; human milk/HM; and infant formula/IF) were investigated using an infant digestion model. During digestion, droplets exhibited different degrees of aggregation, and the order of the particle size was MPL-L > MPL-M > MPL-S. MPL-M and MPL-S were significantly higher than MPL-L in the release of free fatty acids. No significant difference was observed in the FFA release rate between MPLs and HM. However, the rate was significantly higher than that of IF in the intestinal stage. Compared to IF, a higher content of long-chain polyunsaturated fatty acids and a lower content of saturated fatty acid were observed in MPLs and HM.

Bioavailability and bioaccessibility of food bioactive compounds; overview and assessment by in vitro methods

Oral bioavailability is the key to the bioefficiency of food bioactive ingredients; it evaluates the relationship between foods and their health benefits. The analysis of the main factors limiting the oral bioavailability (bioaccessibility, absorption, and transformation) has led to the proposal of classification systems for pharmaceuticals and nutraceuticals (Biopharmaceuticals Classification System and Nutraceutical Bioavailability Classification Scheme). Based on the relevant studies published in the last decade, this review presents the essential aspects regarding the factors limiting the oral bioavailability of the biocomponents and different in vitro methods used to investigate the mechanisms involved in the digestion, absorption, and metabolism of biocomponents, particularly encapsulated bioactive compounds. Oral bioavailability investigated by in vitro studies provides the food and drug manufacturers with information to formulate delivery systems more efficiently and to determine the dosage of biocomponents for increase the health benefits and avoid or reduce the risk of toxicity.

An Experimental Study on Human Milk Rheology: Behavior Changes from External Factors

The influence of external factors, including temperature, storage, aging, time, and shear rate, on the general rheological behavior of raw human milk is investigated. Rotational and oscillatory experiments were performed. Human milk showed non-Newtonian, shear-thinning, thixotropic behavior with both yield and flow stresses. Storage and aging increased milk density and decreased viscosity. In general, increases in temperature lowered density and viscosity with periods of inconsistent behavior noted between 6–16 ∘ C and over 40 ∘ C. Non-homogeneous breakdown between the yield and flow stresses was found which, when coupled with thixotropy, helps identify the source of nutrient losses during tube feeding.

Investigating the Phospholipid Effect on the Bioaccessibility of Rosmarinic Acid-Phospholipid Complex through a Dynamic Gastrointestinal in Vitro Model

Phyto-phospholipid complexes have been developed as a common way of improving the oral bioavailability of poorly absorbable phyto-pharmaceuticals; however, the complexation with phospholipids can induce positive or negative effects on the bioaccessibility of such plant-derived active ingredients in different parts of the gastrointestinal tract (GIT). The purpose of this study was to investigate the effects of phospholipid complexation on the bioaccessibility of a rosmarinic acid-phospholipid complex (RA-PLC) using the TNO dynamic intestinal model-1 (TIM-1). Preparation of RA-PLC was confirmed using X-ray diffraction, Fourier-transform infrared spectroscopy, partition coefficient measurement, and Caco-2 monolayer permeation test. Bioaccessibility parameters in different GIT compartments were investigated. Complexation by phospholipids reduced the bioaccessibility of RA in jejunum compartment, while maintaining the ileum bioaccessibility. The overall bioaccessibility of RA-PLC was lower than the unformulated drug, suggesting that the improved oral absorption from a previous animal study could be considered as a net result of decreased bioaccessibility overwhelmed by enhanced intestinal permeability. This study provides insights into the effects of phospholipid on the bioaccessibility of hydrophilic compounds, and analyzes them based on the relationship between bioaccessibility, membrane permeability, and bioavailability. Additionally, TIM-1 shows promise in the evaluation of dosage forms containing materials with complicated effects on bioaccessibility.

Lipid digestion of oil-in-water emulsions stabilized with low molecular weight surfactants

Altering sn-fatty acid position of glycerol mono-oleate (GMO) from sn-1 to sn-2 decreases fatty acid bioaccessibility by 25.9% providing possible strategies to tailor lipemic responses of food emulsions.

Lipid Profiling, Particle Size Determination, and in Vitro Simulated Gastrointestinal Lipolysis of Mature Human Milk and Infant Formula

Dairy technologists has attempted to produce "improved" infant formulas mimicking human milk by supplementation with bovine MFGM and/or phospholipids-enriched materials. The present study investigated and compared the lipid profile and particle sizes of mature human milk and infant formula fat globules (IF 1, IF 2, IF 3, and IF 4) and elucidated the relationship between physicochemical properties and in vitro simulated gastrointestinal lipolysis rate of the different milk samples. Despite having larger micron-sized fat globules, mature human milk demonstrated the highest gastrointestinal lipolysis rate with higher release of medium- and long-chain saturated fatty acids. In comparison, IF 3, which contained the lowest phospholipids content, demonstrated the lowest gastrointestinal lipolysis rate. Higher gastrointestinal lipolysis rate of mature human milk fat as compared to infant formula fats might be due to the presence of MFGM interfacial layer (phospholipids) surrounding the fat droplets which govern lipase activity on lipid droplets.

Protein Digestion and Quality of Goat and Cow Milk Infant Formula and Human Milk Under Simulated Infant Conditions

OBJECTIVE

The aim of this study was to determine the kinetics of true ileal protein digestion and digestible indispensable amino acid score (DIAAS) of a goat milk-based infant formula (GIF), a cow milk-based infant formula (CIF), and human milk (HM).

METHODS

The GIF, CIF, and HM were investigated in an in vitro gastrointestinal model simulating infant conditions. Digested compounds were dialyzed from the intestinal compartment as bioaccessible fraction. Dialysate was collected in 15 to 60-minute periods for 4 hours. True ileal protein digestibility and DIAAS were determined as bioaccessible nitrogen (N) and amino acids.

RESULTS

N bioaccessibility from the GIF showed similar kinetics to that of HM. The CIF showed a delay in N bioaccessibility versus the GIF and HM. In the 1st hour of digestion, N bioaccessibility was 19.9% ± 3.5% and 23.3% ± 1.3% for the GIF and HM, respectively, and 11.2% ± 0.6% for CIF (P < 0.05 vs HM). In the 3rd hour of digestion, the N bioaccessibility was higher (P < 0.05) for the CIF (28.9% ± 1.2%) than for the GIF (22.5% ± 1.6%) and HM (20.6% ± 1.0%). After 4 hours, the true ileal protein digestibility of the GIF, CIF, and HM was 78.3% ± 3.7%, 73.4% ± 2.7%, and 77.9% ± 4.1%, respectively. The DIAAS for the GIF, CIF, and HM for 0- to 6-month-old infants was 83%, 75%, and 77% for aromatic AA.

CONCLUSION

The protein quality is not different between the GIF, CIF, and HM, but the kinetics of protein digestion of the GIF is more comparable to that of HM than that of the CIF.

Micro- and nano bio-based delivery systems for food applications: In vitro behavior

Micro- and nanoencapsulation is an emerging technology in the food field that potentially allows the improvement of food quality and human health. Bio-based delivery systems of bioactive compounds have a wide variety of morphologies that influence their stability and functional performance. The incorporation of bioactive compounds in food products using micro- and nano-delivery systems may offer extra health benefits, beyond basic nutrition, once their encapsulation may provide protection against undesired environmental conditions (e.g., heat, light and oxygen) along the food chain (including processing and storage), thus improving their bioavailability, while enabling their controlled release and target delivery. This review provides an overview of the bio-based materials currently used for encapsulation of bioactive compounds intended for food applications, as well as the main production techniques employed in the development of micro- and nanosystems. The behavior of such systems and of bioactive compounds entrapped into, throughout in vitro gastrointestinal systems, is also tracked in a critical manner. Comparisons between various in vitro digestion systems (including the main advantages and disadvantages) currently in use, as well as correlations between the behavior of micro- and nanosystems studied through in vitro and in vivo systems were highlighted and discussed here for the first time. Finally, examples of bioactive micro- and nanosystems added to food simulants or to real food matrices are provided, together with a revision of the main challenges for their safe commercialization, the regulatory issues involved and the main legislation aspects.

Bioavailability of Nutrients and Micronutrients: Advances in Modeling and In Vitro Approaches

The bioavailability of food nutrients and microconstituents is recognized as a determinant factor for optimal health status. However, human and animal studies are expensive and limited by the large amount of potential food bioactive compounds. The search for alternatives is very active and raises many questions. On one hand, in vitro digestion systems are good candidates, but to date only bioaccessibility has been correctly assessed. To go further, to what degree should natural processes be reproduced? What techniques can be used to measure the changes in food properties and structures in situ in a noninvasive way? On the other hand, modeling approaches have good potential, but their development is time-consuming. What compromises should be done between food and physiology realism and computational ease? This review addresses these questions by identifying highly resolved analytical methods, detailed computer models and simulations, and the most promising dynamic in vitro systems.