Identification of texture parameters influencing commercial cheese matrix disintegration and lipid digestion using an in vitro static digestion model

An examination of the impact of unmelted, melted, and deconstructed cheese on lipid metabolism: a 6-week randomised trial

Background: Evidence suggests cheese has a favourable or neutral effect on cardiometabolic health, compared to butter. To date, studies have only considered the cheese matrix in its unmelted form, while the effect of melted cheese remains unknown. Objective: To test the effect of 6-week daily consumption of ∼40 g dairy fat, eaten in either as unmelted cheese, melted cheese, or in a fully deconstructed form, on markers of metabolic health in overweight adults aged ≥50 years of age. Design: A 6-week randomised parallel intervention, where 162 participants (43.3% male) received ∼40 g of dairy fat per day, in 1 of 3 treatments: (A) 120 g full-fat Irish grass-fed cheddar cheese, eaten in unmelted form (n 58); (B) 120 g full-fat Irish grass-fed cheddar cheese eaten in melted form (n 53); or (C) the equivalent components; butter (49 g), calcium caseinate powder (30 g), and Ca supplement (CaCO3; 500 mg) (n 51). Results: There was no difference in weight, fasting glucose, or insulin between the groups post-intervention. Melted cheese, compared to unmelted cheese, increased total cholesterol (0.23 ± 0.79 mmol L-1vs. 0.02 ± 0.67 mmol L-1, P = 0.008) and triglyceride concentrations (0.17 ± 0.39 mmol L-1vs. 0.00 ± 0.42 mmol L-1, P = 0.016). Melted cheese increased total cholesterol concentrations by 0.20 ± 0.15 mmol L-1 and triglyceride concentrations by 0.17 ± 0.08 mmol L-1 compared to unmelted cheese. No significant differences were observed between the cheese forms for change in HDL, LDL or VLDL cholesterol. Conclusion: Compared to unmelted cheese, melted cheese was found to increase total cholesterol and triglyceride concentrations in middle-aged, overweight adults with no effect on weight or glycaemic control.

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.

Whole milk dairy foods and cardiometabolic health: dairy fat and beyond

Bovine dairy milk is a nutrient-rich matrix, but consumption of full-fat dairy food varieties has been claimed historically to be associated with poorer cardiometabolic health, a notion often attributed to the saturated fat content. However, continued investigation that includes observational studies and randomized controlled trials (RCTs) provide evidence that favorably supports full-fat dairy foods and their bioactive components on cardiometabolic health. This review addresses this controversy by examining the evidence surrounding full-fat dairy foods and their implications for human health. Dairy foods are heterogeneous, not just in their fat content but also in other compositional aspects within and between fermented (e.g., yogurt, cheese) and nonfermented products (e.g., milk) that could differentially influence cardiometabolic health. Drawing from complementary lines of evidence from epidemiological studies and RCTs, this review describes the health effects of dairy foods regarding their fat content, as well as their polar lipids that are concentrated in the milk fat globule fraction. Observational studies have limitedly supported the consumption of full-fat dairy to protect against cardiometabolic disorders. However, this framework has been disputed by RCTs indicating that dairy foods, regardless of their fat content or fermentation, are not detrimental to cardiometabolic health and may instead alleviate certain cardiometabolic risk factors. As dietary recommendations evolve, which currently indicate to avoid full-fat dairy foods, it is essential to consider the totality of evidence, especially from RCTs, while also recognizing that investigation is needed to evaluate the complexity of dairy foods within diverse dietary patterns and their impacts on cardiometabolic health.

Impact of Milk Storage and Heat Treatments on In Vitro Protein Digestibility of Soft Cheese

Cheese is an important source of protein in the human diet, and its digestibility depends on its macro and microstructure. This study investigated the effect of milk heat pre-treatment and pasteurization level on the protein digestibility of produced cheese. An in vitro digestion method was used considering cheeses after 4 and 21 days of storage. The peptide profile and amino acids (AAs) released in digestion were analyzed to evaluate the level of protein degradation following in vitro digestion. The results showed the presence of shorter peptides in the digested cheese from pre-treated milk and 4-day ripening while this trend was not observed after 21 days of storage, showing the effect of storage period. A significantly higher content of AAs was found in digested cheese produced from milk subjected to a higher temperature of pasteurization, and there was a significant increase in total AA content in the cheese after 21 days of storage, confirming the positive effect of ripening on protein digestibility. From these results emerges the importance of the management of heat treatments on the digestion of proteins in soft cheese.

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.

Dietary lipids and cardiometabolic health: a new vision of structure-activity relationship

PURPOSE OF REVIEW

The impact of dietary lipids on cardiometabolic health was mainly studied considering their fatty acid composition. This review aims to present the recent change in paradigm whereby the food matrix, the molecular and supramolecular structures of dietary lipids modulate their digestive fate and cardiometabolic impact.

RECENT FINDINGS

Epidemiological studies have reported that the metabolic impact of full-fat dairy products is better than predictable upon saturated fatty acid richness. Milk polar lipid supplementation reduced adiposity and inflammation in rodents by modulating gut microbiota and barrier, and decreased lipid markers of cardiovascular disease risk in humans by lowering cholesterol absorption. The metabolic importance of the structure of lipid molecules carrying omega-3 (molecular carrier) has also been documented. Plant lipids exhibit specific assemblies, membrane and molecular structures with potential health benefits. Lipid emulsifiers used to stabilize fats in processed foods are not mere bystanders of lipid effects and can induce both beneficial and adverse health effects.

SUMMARY

These findings open new clinical research questions aiming to further characterize the cardiometabolic fate of lipids, from digestion to bioactive metabolites, according to the food source or molecular carrier. This should be useful to elaborate food formulations for target populations and personalized dietary recommendations.

Higher microbial diversity in raw than in pasteurized milk Raclette-type cheese enhances peptide and metabolite diversity after in vitro digestion

Numerous bacteria are responsible for hydrolysis of proteins during cheese ripening. The raw milk flora is a major source of bacterial variety, starter cultures are needed for successful acidification of the cheese and proteolytic strains like Lactobacillus helveticus, are added for flavor improvement or acceleration of ripening processes. To study the impact of higher bacterial diversity in cheese on protein hydrolysis during simulated human digestion, Raclette-type cheeses were produced from raw or heat treated milk, with or without proteolytic L. helveticus and ripened for 120 days. Kinetic processes were studied with a dynamic (DIDGI®) in vitro protocol and endpoints with the static INFOGEST in vitro digestion protocol, allowing a comparison of the two in vitro protocols at the level of gastric and intestinal endpoints. Both digestion protocols resulted in comparable peptide patterns after intestinal digestion and higher microbial diversity in cheeses led to a more diverse peptidome after simulated digestion.

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.