Fabrication, digestion behavior and β-carotene bioaccessibility of emulsion-filled double-network gel: Effect of corn fiber gum/soy protein isolate ratio and surfactant types

Emulsion fortified with β-carotene was added to corn fiber gum (CFG)/soy protein isolate (SPI) double network gel matrix to obtain emulsion-filled gels (EFG) via dual induction of laccase and glucono-δ-lactone. Protein digestion was accompanied by the release of β-carotene from gel matrix during in vitro digestion. The surfactant types and corn fiber gum/soy protein isolate ratio affected the β-carotene bioaccessibility via changing oil-water interfacial composition and emulsion particle size during in vitro digestion. As compared with Tween-20 EFGs, emulsion droplets released from SPI EFGs was more susceptible to flocculation, followed with coalescence due to proteolysis of interfacial SPI during gastric digestion. The resulting oil droplets with large particle size exhibited lower lipase adsorption, thus reducing the free fatty acid content and β-carotene bioaccessibility. The confocal laser scanning microscope (CLSM) observation confirmed that protein hydrolysate from gel matrix were adsorbed onto the oil-water interface competing with Tween-20 during intestinal digestion. For EFGs with higher CFG content, steric hindrance of CFG molecules and less emulsion release could inhibit droplet flocculation, thus enhancing β-carotene bioaccessibility.

Assessment of protein and phospholipid bioaccessibility in ultrafiltered buttermilk cheese using TIM-1 in vitro gastrointestinal methods

To meet the high consumer demand, butter production has increased over the last few years. As a result, the buttermilk (BM) co-produced volumes require new ways of adding value, such as in cheese manufacturing. However, BM use in cheese milk negatively influences the cheesemaking process (e.g., altered coagulation properties) and the product's final quality (e.g., high moisture content). The concentration of BM by ultrafiltration (UF) could potentially facilitate its use in cheese manufacturing through an increased protein content while maintaining the milk salt balance. Simultaneously, little is known about the digestion of UF BM cheese. Therefore, this study aimed to characterize the impact of UF BM on cheese manufacture, its structure, and its behavior during in vitro digestion. A 2-fold UF concentrated BM was used for cheese manufacture (skim milk [SM] - control). Compositional, textural, and microstructural analyses of cheeses were first conducted. In a second step, the cheeses were fed into an in vitro TNO gastrointestinal digestion model (TIM-1) of the stomach and small intestine and protein and phospholipid (PL) bioaccessibility was studied. The results showed that UF BM cheese significantly differed from SM cheese regarding its composition, hardness (p < 0.05) and microstructure. However, in TIM-1, UF BM and SM cheeses showed similar digestion behavior as a percentage of protein and PL intake. Despite relatively more non-digested and non-absorbed PL in the ileum efflux of UF BM cheese, the initially higher PL concentration contributes to an enhanced nutritional value compared to SM cheese. To our knowledge, this study is the first to compare the bioaccessibility of proteins and PL from UF BM and SM cheeses.

The impact of heat-set milk protein gel textures modified by pH on circulating amino acid appearance and gastric function in healthy female adults: a randomised controlled trial

Modification of dairy proteins during processing impacts structural assemblies, influencing textural and nutritional properties of dairy products, and release and availability of amino acids during digestion. By modifying only pH, acid heat-set bovine dairy gels with divergent textural properties were developed to alter protein digestion. In vitro assay confirmed faster digestion of protein from a firm gel (pH 5.65) versus a soft gel (pH 6.55). We hypothesised that firm gel (FIRM-G; pH 5.6) would result in greater indispensable amino acid (IAA) appearance in circulation over 5 h and corresponding differences in gastric myoelectrical activity relative to soft gel (SOFT-G; pH 6.2). In a randomised, single-blind cross-over trial, healthy females (n = 20) consumed 150 g of each gel; plasma amino acid appearance was assessed over 5 hours. Iso-nitrogenous, iso-caloric gels were prepared from identical mixtures of bovine milk and whey protein concentrates; providing 17.7 g (FIRM-G) and 18.9 g (SOFT-G) of protein per serving. Secondary outcomes included gastric myoelectrical activity measured by body surface gastric mapping, glycaemic, triglyceridaemic, and subjective appetite and digestive responses. Overall plasma IAA (area under the curve) did not differ between gels. However, plasma IAA concentrations were higher, and increased more rapidly over time after SOFT-G compared with FIRM-G (1455 ± 53 versus 1350 ± 62 μmol L-1 at 30 min, p = 0.024). Similarly, total, branched-chain and dispensable amino acids were higher at 30 min with SOFT-G than FIRM-G (total: 3939 ± 97 versus 3702 ± 127 μmol L-1, p = 0.014; branched-chain: 677 ± 30 versus 619 ± 34 μmol L-1, p = 0.047; dispensable: 2334 ± 53 versus 2210 ± 76 μmol L-1, p = 0.032). All other measured parameters were similar between gels. Peak postprandial aminoacidaemia was higher and faster following ingestion of SOFT-G. Customised plasma amino acid appearance from dairy is achievable by altering gel coagulum structure using pH during processing and may have minimal influence on related postprandial responses, with implications for targeting food design for optimal health. The Clinical Trial Registry number is ACTRN12622001418763 (https://www.anzctr.org.au) registered November 7, 2022.

Application of small angle scattering (SAS) in structural characterisation of casein and casein-based products during digestion

In recent years, small and ultra-small angle scattering techniques, collectively known as small angle scattering (SAS) have been used to study various food structures during the digestion process. These techniques play an important role in structural characterisation due to the non-destructive nature (especially when using neutrons), various in situ capabilities and a large length scale (of 1 nm to ∼20 μm) they cover. The application of these techniques in the structural characterisation of dairy products has expanded significantly in recent years. Casein, a major dairy protein, forms the basis of a wide range of gel structures at different length scales. These gel structures have been extensively researched utilising scattering techniques to obtain structural information at the nano and micron scale that complements electron and confocal microscopy. Especially, neutrons have provided opportunity to study these gels in their natural environment by using various in situ options. One such example is understanding changes in casein gel structures during digestion in the gastrointestinal tract, which is essential for designing personalised food structures for a wide range of food-related diseases and improve health outcomes. In this review, we present an overview of casein gels investigated using small angle and ultra-small angle scattering techniques. We also reviewed their digestion using newly built setups recently employed in various research. To gain a greater understanding of micro and nano-scale structural changes during digestion, such as the effect of digestive juices and mechanical breakdown on structure, new setups for semi-solid food materials are needed to be optimised.

Coagulation and proteolysis of high-protein milks in the gastric environment

Gastric digestion of 2 commercial ultrafiltered milks and milk enriched with skim milk powder (to simulate concentration by reverse osmosis) was investigated and compared with the digestion of nonconcentrated milk. Curd formation and proteolysis of high-protein milks in simulated gastric conditions were studied using oscillatory rheology, extrusion testing, and gel electrophoresis. The presence of pepsin in the gastric fluid triggered coagulation at pH >6 and the elastic modulus of gels from high-protein milks was ∼5 times larger than the gel from reference milk. Despite similar protein concentrations, the coagulum from milk enriched with skim milk powder showed higher resistance to shear deformation than the coagula from ultrafiltered milks. The gel structure was also more heterogeneous. During digestion, the degradation of coagula from high-protein milks was slowed down compared with the coagulum from reference milk, and intact milk proteins were still detected after 120 min. Differences in the digestion patterns of coagula from high-protein milks were observed and were associated with the proportion of minerals bound to caseins and the denaturation rate of whey proteins.

New Insights into Cheese Microstructure

Microscopy is often used to assist the development of cheese products, but manufacturers can benefit from a much broader application of these techniques to assess structure formation during processing and structural changes during storage. Microscopy can be used to benchmark processes, optimize process variables, and identify critical control points for process control. Microscopy can also assist the reverse engineering of desired product properties and help troubleshoot production problems to improve cheese quality. This approach can be extended using quantitative analysis, which enables further comparisons between structural features and functional measures used within industry, such as cheese meltability, shreddability, and stretchability, potentially allowing prediction and control of these properties. This review covers advances in the analysis of cheese microstructure, including new techniques, and outlines how these can be applied to understand and improve cheese manufacture.

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.

Vitamin D Incorporation in Foods: Formulation Strategies, Stability, and Bioaccessibility as Affected by the Food Matrix

Inadequate intake of vitamin D is a global health issue related to severe diseases, mainly involving subjects with dark skin pigmentation, patients affected by malnutrition, malabsorption syndromes, or obesity, and elderly people. Some foods fortified with vitamin D have been tested in vivo, but fortification strategies with a global outreach are still lacking. This review is focused on food fortification with vitamin D, with the aim to collect information on (a) formulation strategies; (b) stability during processing and storage; and (c) in vitro bioaccessibility. Approaches to add vitamin D to various foods were analyzed, including the use of free vitamin D, vitamin D loaded in simple and double nanoemulsions, liposomes, casein micelles, and protein nanocapsules. Numerous studies were reviewed to elucidate the impact of food technologies on vitamin D’s stability, and mechanisms that lead to degradation were identified—namely, acid-catalyzed isomerization, radical-induced oxidation, and photo-oxidation. There is, however, a lack of kinetic data that allow for the prediction of vitamin D’s stability under industrial processing conditions. The roles that lipids, proteins, fibers, and antioxidants play in vitamin bioaccessibility have been clarified in various studies, while future needs include the design of specific food matrices that simultaneously achieve a balance between the long-term stability, bioaccessibility and, ultimately, in vivo functionality of vitamin D.

Sous Vide Cook Temperature Alters the Physical Structure and Lipid Bioaccessibility of Beef Longissimus Muscle in TIM-1

Changes in the physical states, induced with different sous vide cooking temperatures, significantly (P < 0.05) altered lipid bioaccessibility measured in the TNO-simulated gastrointestinal tract model-1 of AAA boneless beef striploin, containing the longissimus lumborum muscle. The denaturation of actin significantly correlates with the total cumulative free fatty acid (FFA) bioaccessibility, whereby the striploin cooked to 60 °C presents the maximum lipid bioaccessibility (15.8 ± 1.0%), rate constant (k_a) for FFA hydrolysis (0.087 ± 0.003 min^-1), and greatest actin denaturation enthalpy (-0.57 ± 0.06 ΔH). Thus, thermal treatments above 60 °C significantly decrease the kinetics of lipolysis (70 °C = 0.042 ± 0.002 min^-1 and 80 °C = 0.047 ± 0.002 min^-1) and the resultant total lipid bioaccessibility (70 °C = 8.6 ± 0.7 and 80 °C = 8.3 ± 0.5%). This research highlights the potential to manipulate the physical food structure to alter digestion kinetics, supporting the need to understand supramolecular structures in food and their nutritional outcomes.

Nutrigenomics of Dietary Lipids

Dietary lipids have a major role in nutrition, not only for their fuel value, but also as essential and bioactive nutrients. This narrative review aims to describe the current evidence on nutrigenomic effects of dietary lipids. Firstly, the different chemical and biological properties of fatty acids contained both in plant- and animal-based food are illustrated. A description of lipid bioavailability, bioaccessibility, and lipotoxicity is provided, together with an overview of the modulatory role of lipids as pro- or anti-inflammatory agents. Current findings concerning the metabolic impact of lipids on gene expression, epigenome, and gut microbiome in animal and human studies are summarized. Finally, the effect of the individual’s genetic make-up on lipid metabolism is described. The main goal is to provide an overview about the interaction between dietary lipids and the genome, by identifying and discussing recent scientific evidence, recognizing strengths and weaknesses, to address future investigations and fill the gaps in the current knowledge on metabolic impact of dietary fats on health.

Achieving realistic gastric emptying curve in an advanced dynamic in vitro human digestion system: experiences with cheese-a difficult to empty material

Nowadays, in vitro digestion models have received growing interest in recent years to track the digestive fate of foods in the gastrointestinal tract. A major challenge in the development of more physiologically relevant in vitro gastric models is to simulate realistic gastric emptying. In this study, an advanced dynamic in vitro human gastric system was investigated for its potential in achieving the above. The mechanisms for controlling the gastric emptying rate by modulations of the peristaltic moving distance, the pylorus opening size/frequency, and the stomach tilting angle in relation to time are illustrated. With solid cheese, a difficult food material for emptying, different combinations of the operational parameters of the stomach system were evaluated. The system was steered to attain consistent gastric emptying curve with the theoretical data by optimizing operational parameters. By fitting the gastric retention data with a power-exponential model, which is a common approach for describing gastric emptying, the total meal achieved an average emptying half-time (t1/2) of 84.5 min and a curve shape coefficient (β) of 1.69, similar to the theoretical data reported in the literature, where the values of t1/2 and β were 85 min and 1.8, respectively (p > 0.05). Furthermore, the mean median particle size was significantly decreased from the initial 2.80 mm (cheese cubes) to the final 1.35 mm (p < 0.05). There are few particles greater than 2 mm observed in the emptied cheese digesta throughout the digestion process. These suggest the powerful gastric grinding and sieving capacity exhibited by the in vitro system. The current study demonstrates that a well-considered in vitro system can offer a reasonable approach for tracking the structural and physicochemical changes of foods during digestion in the stomach, which is practically meaningful.

Influence of type of dairy matrix micro- and macrostructure on in vitro lipid digestion

Recent research indicates that the food matrix can influence digestion kinetics and uptake of nutrients, thus affecting human health. The aim of this study was to obtain knowledge on how variations in microstructure and texture of foods represented by four dairy products; (i) cheddar cheese, (ii) a homogenized cheddar cheese, (iii) a micellar casein and cream drink or (iv) a micellar casein and cream gel, all of identical nutrient ratios of protein : fat and calcium : fat, affect the in vitro digestibility kinetics of lipids. Rheology of the four dairy structures was measured at 10 °C and 37 °C before digestion, and during the gastric phase of in vitro digestion. During digestion cheddar cheese was most resistant to enzymatic and mechanical disintegration, followed by homogenized cheese, while both the drink and gel had low resistance and dissolved in the gastric juice. Particle size, fat droplet size and microstructure were assessed by light scattering and confocal microscopy during digestion. Significantly larger fat droplets were observed during digestion of the cheddar cheese sample. The release of free fatty acids during the initial intestinal digestion showed cheddar cheese to provide a significantly lower release than homogenized cheese, whereas the drink and gel both had significantly higher free fatty acid release. The results suggest that the cheese matrix resistance to degradation and its large fat droplets were responsible for a slower fat digestion.

Impact of Cooking Preparation on In Vitro Digestion of Eggs Simulating Some Gastrointestinal Alterations in Elders

This study aimed to in vitro assess the impact of the cooking process of eggs (hard-boiled, poached, and omelet) on nutrients digestibility and vitamins A and D3 bioaccessibility under elderly gastrointestinal (GI) conditions. Three elderly digestion models were mimicked: oral (E1); oral and gastric (E2); and oral, gastric, and intestinal (E3), and a healthy adult model (C). Proteolysis extent reduced after digestion of omelet under the E3 model (p < 0.05) (up to 37% of reduction). Thus, hard-boiled and poached were more recommendable to enhance protein digestibility in elders. Altered GI conditions negatively influence neither the absorbable lipid fraction nor the cholesterol stability. Finally, vitamin A bioaccessibility was not affected but D3 slightly decreased with the elderly (E3). Hence, the digestion of nutrients was dependent on the resulting matrix, poached being the greater supplier of protein and lipid end-digestion products. Poached and omelet, however, offer a high net supply of bioaccessible vitamin D3 for elders.

Investigation of the Formation Mechanism and Curcumin Bioaccessibility of Emulsion Gels Based on Sugar Beet Pectin and Laccase Catalysis

In this study, modified whey protein hydrolysates (WPH) were obtained after succinic anhydride succinylation and linear dextrin glycation, and emulsion gels were prepared on the basis of unmodified/modified WPH stabilized emulsions with sugar beet pectin (SBP) addition and laccase-catalyzed cross-linking. The influences of emulsifier types and SBP contents on the texture of emulsion gels were estimated. The texture and rheological properties of emulsion gels were characterized. An ideal gel emulsion was formed when the SBP content was 3% (w/w). A uniform network was observed in emulsion gels stabilized by W-L, W-L-S, and W-S-L. In addition, the effect of the emulsifier type on the bioaccessibility of curcumin encapsulated in emulsion gels was investigated and the W-S-L stabilized emulsion gel exhibited the highest curcumin bioaccessibility (65.57%). This study provides a theoretical basis for the development of emulsion gels with different textures by SBP addition and laccase cross-linking as encapsulation delivery systems.

Cheese as a functional food for older adults: comparing the bioactive properties of different cheese matrices following simulated gastrointestinal in vitro digestion

Age-related changes to the gastrointestinal tract (GIT) can impact how food is digested. Studying the effects of these changes can help identify functional foods for older adults. Cheese was digested using two simulated gastrointestinal in vitro digestion (SGID) models representing adult and elderly gastro-intestinal conditions. Antioxidant capacity was measured using DPPH, FRAP and TPC assays. The ability of cheese to inhibit digestive enzymes was determined by the α-glucosidase and lipase inhibition assays. Digestive aging influenced the bioactivity of cheese, as elderly digestates had significantly lower (p < 0.05) antioxidant, α-glucosidase and lipase inhibitory properties compared to adult digestates. However, soft cheese (feta, goats', brie) demonstrated greatest potential with comparable radical scavenging properties and lipase inhibition, greatest FRAP and α-glucosidase inhibitory potential. Despite age-related changes, the bioactive properties of cheese were evident following digestion with an older adult SGID model, suggesting cheese has potential as a functional food for older adults.

Impact of Processing and Intestinal Conditions on in Vitro Digestion of Chia (Salvia hispanica) Seeds and Derivatives

Chia seeds present with an excellent nutrient profile, including polyunsaturated fat, protein, fibre and bioactive compounds, which make them a potential food or ingredient to bring beneficial health effects. However, their tough structure could mean that these seeds remain hardly disrupted during digestion, thus preventing the release and digestibility of nutrients. In the present study, different chia products (seeds, whole flour, partially defatted flour and sprouts) were assessed in terms of proteolysis, lipolysis, calcium and polyphenols bioaccessibility and antioxidant activity. In vitro digestions were performed supporting standard intestinal (pH 7, bile salts concentration 10 mM) and altered (pH 6, bile salts concentration 1 mM) conditions. The altered conditions significantly reduced lipolysis, but not proteolysis. Regarding the food matrix, compared to the chia seeds, whole and partially defatted flour increased the hydrolysis of lipids and protein, relating to reduced particle size. Sprouting had an enhancing effect on proteolysis but prevented lipolysis. Calcium bioaccessibility dropped in all the samples in the two intestinal conditions. The digestion process led to increased polyphenols bioaccessibility in all the structures, but reduced antioxidant activity except in the milled structures. In conclusion, milling should be applied to chia seeds prior to consumption in cases where enhancing the potential uptake of macro and micronutrients is targeted, and sprouting is suitable to enhance protein digestibility and reduce lipolysis.

Dairy structures and physiological responses: a matter of gastric digestion

Digestion and health properties of food do not solely rely on the sum of nutrients but are also influenced by food structure. Dairy products present an array of structures due to differences in the origin of milk components and the changes induced by processing. Some dairy structures have been observed to induce specific effects on digestion rates and physiological responses. However, the underlying mechanisms are not fully understood. Gastric digestion plays a key role in controlling digestion kinetics. The main objective of this review is to expose the relevance of gastric phase as the link between dairy structures and physiological responses. The focus is on human and animal studies, and physiological relevant in vitro digestion models. Data collected showed that the structure of dairy products have a profound impact on rate of nutrient bioavailability, absorption and physiological responses, suggesting gastric digestion as the main driver. Control of gastric digestion can be a tool for delivering specific rates of nutrient digestion. Therefore, the design of food structure targeting specific gastric behavior could be of great interest for particular population needs e.g. rapid nutrient digestion will benefit elderly, and slow nutrient digestion could help to enhance satiety.

Symposium review: The dairy matrix-Bioaccessibility and bioavailability of nutrients and physiological effects

Several studies have linked food structure and texture to different kinetics of nutrients delivery. Changes in some nutrients' release rate, such as proteins and lipids, could induce different physiological effects (e.g., satiety effect, reduction of postprandial lipemia). Recently, experts are proposing to consider the food as a whole instead of looking at specific nutrients, as the combination of food components and the way they are structured could change their physiological effects. This review highlights recent knowledge linking the different levels of structure of dairy products to their digestion, absorption, and physiological effects. Two examples, yogurt and cheese, will be presented to showcase the contributions of dairy food structure to nutrient release rates. One study aimed to validate whether changes in the casein:whey protein ratio or addition of fiber could influence the digestion kinetics of protein and, subsequently, satiety. A static in vitro digestion model has been used on experimental yogurts differing by their casein:whey protein ratio or dietary fiber content. A human trial with healthy men (n = 20) consuming 5 isocaloric and isoproteinemic yogurt snacks before monitoring lunch intake revealed that the yogurt formulation with increased whey protein content significantly reduced subsequent energy intake compared with its control. This result was linked to slower in vitro disintegration rate and soluble protein release for yogurts with increased whey protein, whereas no difference was observed for yogurts with fiber. A second study allowed discrimination between the effects of cheese attributes on lipid release and absorption. Nine commercial cheeses were digested in vitro, and 2 were selected for the in vivo study, in which plasma concentrations of triglycerides (TAG) were followed before and after meal consumption. The in vivo study revealed that cream cheese, but not cheddar, induced a greater increase in TAG concentrations at 2 h than did butter; this difference was linked to their in vitro disintegration. These studies demonstrate that the dairy food matrix per se modulates foods' nutritional properties. Other studies recently published on this topic will also be included, to put in perspective the important role of the dairy food matrix on release of nutrients and their physiological effects, and how this can be compared with other foods.

Role of the food matrix and digestion on calculation of the actual energy content of food

The energy content of food is calculated on the basis of general factors for fat, protein, and carbohydrates. These general factors were derived by W.O. Atwater in the late 19th century, while additional factors for dietary fiber, polyols, and organic acids were introduced more recently. These factors are applied indiscriminately to all types of foods, yet the same nutrient may be digested to different extents to generate energy, depending on the characteristics of the food matrix, the processing methods applied to foods, and the meal composition. As a consequence, the actual energy content of food may differ from what is theoretically calculated with the Atwater factors. In this review, the relationship of macronutrient digestibility with food structure, macronutrient structure, and food composition is examined, and the implications for the amount of energy achievable through diet are highlighted. Estimates of the discrepancy between calculated energy content and actual energy content are provided for different diets. The findings may have implications for consumer purchasing decisions as well as for the design of dietary interventions.

Reprint of "Postprandial lipemia and fecal fat excretion in rats is affected by the calcium content and type of milk fat present in Cheddar-type cheeses"

The aim of this study was to better understand the effect of calcium on the bioavailability of milk lipids from a cheese matrix using a rat model. Cheddar-type cheeses were manufactured with one of three types of anhydrous milk fat, control, olein or stearin, and salted with or without CaCl₂. The cheeses were fed to rats and postprandial lipemia was monitored. Feces were analyzed to quantify fatty acids excreted as calcium soaps. Higher calcium concentration in cheese caused a higher and faster triacylglycerol peak in blood, except for cheeses containing stearin. Furthermore, calcium soaps were more abundant in feces when the ingested cheese had been enriched with calcium and when the cheese was prepared with stearin. Increased lipid excretion was attributable to the affinity of saturated long-chain fatty acids for calcium. Results showed that lipid bioaccessibility can be regulated by calcium present in Cheddar cheese. This study highlights the nutritional interaction between calcium and lipids present in the dairy matrix and confirms its physiological repercussions on fatty acid bioavailability.

Microstructure of a Model Fresh Cheese and Bioaccessibility of Vitamin D₃ Using In Vitro Digestion

In this study, the effect of a composition (protein to fat (P/F) ratio) and a processing condition (homogenization pressure for emulsification of cheese milk) on the texture, microstructure, and bioaccessibility of vitamin D₃ of a model acid coagulated fresh cheese was evaluated. It was hypothesized that increasing P/F ratios (0.9, 1.3, 1.7, and 2) and homogenization pressures (17, 50, 75, and 150 MPa) will decrease the particle size of the cheese milk emulsion. The decreased emulsion particle size will result in a more rigid and elastic cheese matrix with smaller pore sizes, with an increased interfacial surface area of fat particles, which will then improve the bioaccessibility of vitamin D₃. The P/F ratio exhibited a positive impact on the texture in a large deformation analysis. On the other hand, the effect of the P/F ratio and homogenization pressure was not significant on rheological properties of the cheese using a small deformation by means of a frequency sweep test, nor the porosity determined by environmental scanning electron microscopy (ESEM). These results suggested that the modification of the microstructure of acid coagulated fresh cheeses required other variables than P/F ratio and homogenization pressure probably due to a compression step after curd formation. Interestingly, the bioaccessibility of vitamin D₃ measured by in vitro digestion was reduced as P/F ratio and homogenization pressure increased, which may indicate a reinforced protein⁻protein interaction that affected protein hydrolysis.

Food Matrix Design for Effective Lactic Acid Bacteria Delivery

The range of foods featuring lactic acid bacteria (LAB) with potential associated health benefits has expanded over the years from traditional dairy products to meat, cereals, vegetables and fruits, chocolate, etc. All these new carriers need to be compared for their efficacy to protect, carry, and deliver LAB, but because of their profusion and the diversity of methods this remains difficult. This review points out the advantages and disadvantages of the main food matrix types, and an additional distinction between dairy and nondairy foods is made. The food matrix impact on LAB viability during food manufacturing, storage, and digestion is also discussed. The authors propose an ideal hypothetical food matrix that includes structural and physicochemical characteristics such as pH, water activity, and buffering capacities, all of which need to be taken into account when performing LAB food matrix design. Guidelines are finally provided to optimize food matrix design in terms of effective LAB delivery.

Influence of food structure on dairy protein, lipid and calcium bioavailability: A narrative review of evidence

Beyond nutrient composition matrix plays an important role on food health potential, notably acting on the kinetics of nutrient release, and finally on their bioavailability. This is particularly true for dairy products that present both solid (cheeses), semi-solid (yogurts) and liquid (milks) matrices. The main objective of this narrative review has been to synthesize available data in relation with the impact of physical structure of main dairy matrices on nutrient bio-accessibility, bioavailability and metabolic effects, in vitro, in animals and in humans. Focus has been made on dairy nutrients the most studied, i.e., proteins, lipids and calcium. Data collected show different kinetics of bioavailability of amino acids, fatty acids and calcium according to the physicochemical parameters of these matrices, including compactness, hardness, elasticity, protein/lipid ratio, P/Ca ratio, effect of ferments, size of fat globules, and possibly other qualitative parameters yet to be discovered. This could be of great interest for the development of innovative dairy products for older populations, sometimes in protein denutrition or with poor dentition, involving the development of dairy matrices with optimized metabolic effects by playing on gastric retention time and thus on the kinetics of release of the amino acids within bloodstream.

Postprandial lipemia and fecal fat excretion in rats is affected by the calcium content and type of milk fat present in Cheddar-type cheeses

The aim of this study was to better understand the effect of calcium on the bioavailability of milk lipids from a cheese matrix using a rat model. Cheddar-type cheeses were manufactured with one of three types of anhydrous milk fat, control, olein or stearin, and salted with or without CaCl₂. The cheeses were fed to rats and postprandial lipemia was monitored. Feces were analyzed to quantify fatty acids excreted as calcium soaps. Higher calcium concentration in cheese caused a higher and faster triacylglycerol peak in blood, except for cheeses containing stearin. Furthermore, calcium soaps were more abundant in feces when the ingested cheese had been enriched with calcium and when the cheese was prepared with stearin. Increased lipid excretion was attributable to the affinity of saturated long-chain fatty acids for calcium. Results showed that lipid bioaccessibility can be regulated by calcium present in Cheddar cheese. This study highlights the nutritional interaction between calcium and lipids present in the dairy matrix and confirms its physiological repercussions on fatty acid bioavailability.

Increasing Antioxidant Activity and Protein Digestibility in Phaseolus vulgaris and Avena sativa by Fermentation with the Pleurotus ostreatus Fungus

The aim of the research was to determine the impact of fermentation with Pleurotus ostreatus on kidney beans, black beans, and oats. The results indicate that the fungus has a positive effect on the substrates when compared to the controls. The antioxidant activity (39.5% on kidney beans and 225% on oats in relation to the controls) and content of total polyphenols (kidney beans three times higher regarding the controls) increased significantly by the presence of the fungus mycelium, even after simulated digestion. There was a significant increase in protein digestibility (from 39.99 to 48.13% in black beans, 44.06 to 69.01% in kidney beans, and 63.25 to 70.01% in oats) and a decrease of antinutrient tannins (from 65.21 to 22.07 mg in black beans, 35.54 to 23.37 in kidney beans, and 55.67 to 28.11 in oats) as well as an increase in the contents of some essential amino acids. Overall, this fermentation treatment with Pleurotus ostreatus improved the nutritional quality of cereals and legumes, making them potential ingredients for the elaboration and/or fortification of foods for human nutrition.

Differential impact of the cheese matrix on the postprandial lipid response: a randomized, crossover, controlled trial

Background: In a simulated gastrointestinal environment, the cheese matrix modulates dairy fat digestion. However, to our knowledge, the impact of the cheese matrix on postprandial lipemia in humans has not yet been evaluated.Objective: In healthy subjects, we compared the impact of dairy fat provided from firm cheese, soft cream cheese, and butter on the postprandial response at 4 h and on the incremental area under the curve (iAUC) of plasma triglycerides.Design: Forty-three healthy subjects were recruited to this randomized, crossover, controlled trial. In random order at intervals of 14 d and after a 12-h fast, subjects ingested 33 g fat from a firm cheese (young cheddar), a soft cream cheese (cream cheese), or butter (control) incorporated into standardized meals that were matched for macronutrient content. Plasma concentrations of triglycerides were measured immediately before the meal and 2, 4, 6, and 8 h after the meal.Results: Cheddar cheese, cream cheese, and butter induced similar increases in triglyceride concentrations at 4 h (change from baseline: +59%, +59%, and +62%, respectively; P = 0.9). No difference in the triglyceride iAUC_{0-8 h} (P-meal = 0.9) was observed between the 3 meals. However, at 2 h, the triglyceride response caused by the cream cheese (change from baseline: +44%) was significantly greater than that induced by butter (change from baseline: +24%; P = 0.002) and cheddar cheese (change from baseline: +16%; P = 0.0004). At 6 h, the triglyceride response induced by cream cheese was significantly attenuated compared with that induced by cheddar cheese (change from baseline: +14% compared with +42%; P = 0.0004).Conclusion: This study demonstrates that the cheese matrix modulates the impact of dairy fat on postprandial lipemia in healthy subjects. This trial was registered at clinicaltrials.gov as NCT02623790.

Symposium review: Structure-function relationships in cheese

The quality and commercial value of cheese are primarily determined by its physico-chemical properties (e.g., melt, stretch, flow, and color), specific sensory attributes (e.g., flavor, texture, and mouthfeel), usage characteristics (e.g., convenience), and nutritional properties (e.g., nutrient profile, bioavailability, and digestibility). Many of these functionalities are determined by cheese structure, requiring an appropriate understanding of the relationships between structure and functionality to design bespoke functionalities. This review provides an overview of a broad range of functional properties of cheese and how they are influenced by the structural organization of cheese components and their interactions, as well as how they are influenced by environmental factors (e.g., pH and temperature).

The Physical State of Emulsified Edible Oil Modulates Its in Vitro Digestion

Emulsified lipid digestion was tailored by manipulating the physical state of dispersed oil droplets in whey protein stabilized oil-in-water (O/W) emulsions, where the oil phase consisted of one of five ratios of soybean oil (SO) and fully hydrogenated soybean oil (FHSO). The evolution in particle size distribution, structural changes during oral, gastric, and intestinal digestion, and free fatty acid release during intestinal digestion were all investigated. Irrespective of the physical state and structure of the dispersed oil/fat, all emulsions were stable against droplet size increases during oral digestion. During gastric digestion, the 50:50 SO:FHSO emulsion was more stable against physical breakdown than any other emulsion. All emulsions underwent flocculation and coalescence or partial coalescence upon intestinal digestion, with the SO emulsion being hydrolyzed the most rapidly. The melting point of all emulsions containing FHSO was above 37 °C, with the presence of solid fat within the dispersed oil droplets greatly limiting lipolysis. Fat crystal polymorph and nanoplatelet size did not play an important role in the rate and extent of lipid digestion. Free fatty acid release modeled by the Weibull distribution function showed that the rate of lipid digestion (κ) decreased with increasing solid fat content, and followed an exponential relationship (R² = 0.95). Overall, lipid digestion was heavily altered by the physical state of the dispersed oil phase within O/W emulsions.