Impact of cell wall encapsulation of almonds on in vitro duodenal lipolysis

Evaluating the roles of food matrix, lipid micronutrients and bioactives in controlling postprandial hypertriglyceridaemia and inflammation

Lipids play an important role in human nutrition. Although adequate lipid consumption is necessary for an optimal functioning of the human body, overconsumption of saturated fatty acids can lead to postprandial hypertriglyceridaemia, which triggers the development of atherosclerosis. Important parameters that impact postprandial lipaemia and inflammation are related to the matrix structure and the fat-soluble micronutrient profile of ingested foods/lipids, but the specific effect of these parameters should be further studied, as most of the available studies evaluate their effect at fasting state. This review specifically explores the effects of food structure and fat-soluble micronutrients, from either micronutrient-rich foods or supplements, on postprandial hypertriglyceridaemia and inflammation. The review also highlights the potential of emerging biomarkers such as miRNAs or circulating microvesicles, as an alternative to the widely use biomarkers (e.g. low-density lipoproteins or blood concentration of pro-inflammatory cytokines), to identify inflammation associated with postprandial hypertriglyceridaemia at early stages.

The Dairy Matrix: Its Importance, Definition, and Current Application in the Context of Nutrition and Health

Nutrition research has shifted from single nutrients to examining the association of foods and dietary patterns with health. This includes recognizing that food is more than the sum of the individual nutrients and relates to the concept of the food matrix. Like other foods, dairy foods are characterized by their unique matrices and associated health effects. Although the concepts of the food matrix and/or dairy matrix are receiving increasing attention in the nutrition and health literature, there are different terms and definitions that refer to it. This article aims to provide insights into the application of the concepts of the food matrix and dairy matrix and to provide a current overview of the definitions and terminology surrounding the food matrix and dairy matrix. By analysing these aspects, we aim to illustrate the practical implications of the food matrix and dairy matrix on nutrition and health outcomes and evaluate their roles in shaping evidence-based policies for the benefit of public health. There is a need for harmonized definitions within the literature. Therefore, the International Dairy Federation put forward harmonized terms to be internationally applicable: the "dairy matrix" describes the unique structure of a dairy food, its components (e.g., nutrients and non-nutrients), and how they interact; "dairy matrix health effects" refers to the impact of a dairy food on health that extend beyond its individual components.

Bile conjugation and its effect on in vitro lipolysis of emulsions

Bile Salts (BS) are responsible for stimulating lipid digestion in our organism. Gut microbiota are responsible for the deconjugation process of primary conjugated to secondary unconjugated BS. We use two structurally distinct BS and characterize the rate of lipolysis as a compound parameter. A static in-vitro digestion model as well as meta-analysis of literature data has been performed to determine the most influential factors affecting the lipid digestion process. The results demonstrate that lipolysis of emulsions using conjugated BS (NaTC, FFA = 60.0 %, CMC in SIF = 5.58 mM, MSR of linoleic acid = 0.21, rate of adsorption = -0.057 mN/m.s) enhances the release of FFA compared to deconjugated BS (NaDC, FFA = 49.5 %, CMC in SIF = 2.49 mM, MSR of linoleic acid = 0.16 rate of adsorption = -0.064 mN/m.s). These results indicate that conjugation plays an important role in controlling the rate of lipolysis in our organism which can be in turn, tuned by the microflora composition of our gut, ultimately controlling the rate of deconjugation of the BS.

Dry beans (Phaseolus vulgaris L.) modulate the kinetics of lipid digestion in vitro: Impact of the bean matrix and processing

The lipid-lowering effect of dry beans and their impact on lipid and cholesterol metabolism have been established. This study investigates the underlying mechanisms of this effect and explore how the structural integrity of processed beans influences their ability to modulate lipolysis using the INFOGEST static in vitro digestion model. Dietary fiber (DF) fractions were found to decrease lipolysis by increasing the digesta viscosity, leading to depletion-flocculation and/or coalescence of lipid droplets. Bean flours exhibited a more pronounced reduction in lipolysis compared to DF. Furthermore, different levels of bean structural integrity showed varying effects on modulating lipolysis, with medium-sized bean particles demonstrating a stronger reduction. Hydrothermal treatment compromised the ability of beans to modulate lipid digestion, while hydrostatic-pressure treatment (600 MPa/5min) enhanced the effect. These findings highlight that the lipid-lowering effect of beans is not solely attributed to DF but also to the overall bean matrix, which can be manipulated through processing techniques.

The Metabolizable Energy and Lipid Bioaccessibility of Tree Nuts and Peanuts: A Systematic Review with Narrative Synthesis of Human and In Vitro Studies

Nuts are an energy-dense food, yet regular consumption is not associated with weight gain. A proportion of the fats found within nuts remains encapsulated within cell walls and cannot be digested. Metabolizable energy (ME) can be explored by measuring fecal fat excretion in human studies and fat release among in vitro studies. This systematic review with narrative synthesis aimed to examine the ME of tree nuts and peanuts (PROSPERO CRD42021252287). PubMed, MEDLINE, CINAHL, Cochrane, and Embase databases were searched to June 2021. Both in vitro and human studies (adults ≥18 y) were included. Data was synthesized via narrative synthesis with results reported in summary tables and compared between form, processing, and dose of nuts, where available. Twenty-one studies were included. The ME of nuts was consistently lower than that predicted by Atwater factors for investigated nut types (almonds, cashews, hazelnuts, pistachios, walnuts, and peanuts). The mechanisms may relate to a lower fat release from nuts, hence higher fecal fat excretion; however, this review did not consider the digestibility of carbohydrates and protein, which should be considered when interpreting the outcomes. ME was influenced by nut type (ME = 22.6 kJ/g for pistachios; ME = 18.5 kJ/g for raw almonds), physical form (flour > chopped > whole nuts), heat processing (butter > roasted > raw) and dose of consumption. The lower-than-expected ME may explain a lack of association between nut intake and body weight observed in the literature and has implications for the development of food composition databases, food labeling, and informing dietary guidelines. However, the strength of the evidence base was reduced by the variation in methods used between studies, suggesting that further clinical trials are needed to determine the impact of the findings of this review for clinical dietetics.

A review on some properties of almond: ımpact of processing, fatty acids, polyphenols, nutrients, bioactive properties, and health aspects

This review was focused on the proximate compounds, nutritional values, total phenolic, flavonoid, antioxidant activity, fatty acid profile, polyphenols, health aspects and uses of almond kernel and oils. Almond contained about 24-73% crude oil, 50-84% oleic and 6-37% linoleic acids, 77-3908 mg/kg β-stosterol and 5-8 mg/100 g β-tocopherol. Almonds are a good source of mono- and unsaturated fatty acids, phytochemicals, bioactive components, minerals, vitamin E, polyphenols and phytosterols and at the same time almonds have healing effects. Since almond seeds or seed oils have versatile uses, they are consumed on their own or as part of a range of food products. Almonds are considered a healthy snack when consumed due to their potential cardioprotective effects. Since the composition of almonds and its effects on health will be effective both during cultivation and processing, studies should be carried out in a way that preserves the product quality.

Graphical abstract

In this study, the proximate compounds, harvest and irrigation effect, nutritional values (protein, amino acids, vitamins minerals), total phenol, flavonoid, antioxidant activity, fatty acid profile, polyphenols, and uses of almond kernel and oils were summarized.

Effect of Nuts on Gastrointestinal Health

Nuts are high nutrient-dense foods containing healthy lipids, dietary fiber, and bioactive phytochemicals, including vitamins and minerals. Although the beneficial effect of nut consumption on different chronic diseases has been well documented, especially in relation to their cardiometabolic benefits, less scientific evidence is available on their possible beneficial effects on gastrointestinal health. In this narrative review, we summarize the most important findings and new research perspectives in relation to the importance of nut consumption on gastrointestinal health. The integrity of the cell wall structure, cell size and particle size after mastication are known to play a crucial role in energy, nutrient and bioactive release from nuts during digestion, therefore affecting bioaccessibility. Other mechanisms, such as cell wall composition, thickness and porosity, as well as stability of the membranes surrounding the oil bodies within the cell, are also important for energy extraction. As the undigested nutrients and phytochemicals are delivered to the colon, effects on gut microbiota composition are predicted. Although the overall effect of nut consumption on microbial alpha- and beta-diversity has been inconsistent, some scientific evidence suggests an increase in fecal butyrate after almond consumption, and a beneficial role of walnuts on the prevention of ulcerative colitis and protection against the development of gastric mucosal lesions.

Intrinsic dietary fibers and the gut microbiome: Rediscovering the benefits of the plant cell matrix for human health

Dietary fibers contribute to structure and storage reserves of plant foods and fundamentally impact human health, partly by involving the intestinal microbiota, notably in the colon. Considerable attention has been given to unraveling the interaction between fiber type and gut microbiota utilization, focusing mainly on single, purified fibers. Studying these fibers in isolation might give us insights into specific fiber effects, but neglects how dietary fibers are consumed daily and impact our digestive tract: as intrinsic structures that include the cell matrix and content of plant tissues. Like our ancestors we consume fibers that are entangled in a complex network of plants cell walls that further encapsulate and shield intra-cellular fibers, such as fructans and other components from immediate breakdown. Hence, the physiological behavior and consequent microbial breakdown of these intrinsic fibers differs from that of single, purified fibers, potentially entailing unexplored health effects. In this mini-review we explain the difference between intrinsic and isolated fibers and discuss their differential impact on digestion. Subsequently, we elaborate on how food processing influences intrinsic fiber structure and summarize available human intervention studies that used intrinsic fibers to assess gut microbiota modulation and related health outcomes. Finally, we explore current research gaps and consequences of the intrinsic plant tissue structure for future research. We postulate that instead of further processing our already (extensively) processed foods to create new products, we should minimize this processing and exploit the intrinsic health benefits that are associated with the original cell matrix of plant tissues.

Improving bioaccessibility and physicochemical property of blue-grained wholemeal flour by steam explosion

Whole grain contains many health-promoting ingredients, but due to its poor bioaccessibility and processibility, it is not widely accepted by consumers. The steam explosion was exploited to modify the nutritional bioaccessibility and the physicochemical properties of wholemeal flour in this study. In vitro starch digestibility, in vitro protein digestibility of wholemeal flour, total flavonoids content, and total phenolics content of digestive juice were used to evaluate the bioaccessibility, and a significant variation (p < 0.05) was noted. Results showed that steam explosion enhanced the gastric protein digestibility ranged from 5.67 to 6.92% and the intestinal protein digestibility ranged from 16.77 to 49.12%. Steam-exploded wholemeal flour (0.5 MPa, 5 min) had the highest protein digestibility and rapidly digestible starch content. Compared with native flour, steam explosion (0.5 MPa, 5 min) contributed to a 0.72-fold and 0.33-fold increment of total flavonoids content and total phenolics content in digestible juice. Chemical changes of wholemeal flour, induced by steam explosion, caused the changes in the solvent retention capacity, rheological property of wholemeal flour, and altered the falling number (and liquefaction number). An increasing tendency to solid-like behavior and the gel strength of wholemeal flour was significantly enhanced by the steam explosion at 0.5 MPa for 5 min, while the gluten was not weakened. This study indicated that steam-exploded wholemeal flour (0.5 MPa, 5 min) could serve as a potential ingredient with the noticeable bioaccessibility and physicochemical properties in cereal products.

The Almond (Prunus dulcis): Chemical Properties, Utilization, and Valorization of Coproducts

Almonds (Prunus dulcis) are one of the most consumed tree-nuts worldwide, with commercial production in arid environments such as California, Spain, and Australia. The high consumption of almonds is partly due to their versatile usage in products such as gluten-free flour and dairy alternatives as well as them being a source of protein in vegetarian diets. They contain high concentrations of health-promoting compounds such as Vitamin E and have demonstrated benefits for reducing the risk of cardiovascular disease and improving vascular health. In addition, almonds are the least allergenic tree nut and contain minute quantities of cyanogenic glycosides. Production has increased significantly in the past two decades with 3.12 billion pounds of kernel meat produced in California alone in 2020 (USDA 2021), leading to a new emphasis on the valorization of the coproducts (e.g., hulls, shells, skins, and blanch water). This article presents a review of the chemical composition of almond kernels (e.g., macro and micronutrients, phenolic compounds, cyanogenic glycosides, and allergens) and the current research exploring the valorization of almond coproducts. 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.

Almond Bioaccessibility in a Randomized Crossover Trial: Is a Calorie a Calorie?

OBJECTIVE

To investigate the energy and macronutrient bioaccessibility of almonds in individuals with hyperlipidemia.

METHODS

In a previously reported randomized crossover trial, men and postmenopausal women with hyperlipidemia incorporated 3 isoenergetic supplements into a National Cholesterol Education Program Step 2 diet for 1 month each between September 20, 2000, and June 27, 2001. Supplements provided consisted of full-dose almonds (73±5 g/d), half-dose almonds (38±3 g/d) plus half-dose muffins, and full-dose muffins (control). Energy and macronutrients, including individual fatty acids, were measured in the dietary supplements and fecal samples using gas chromatography and Association of Official Analytical Chemists methods. Serum was measured for lipids and fatty acids. Bioaccessibility of energy and macronutrients from almond consumption was assessed from dietary intake (7-day food records) and fecal output.

RESULTS

Almond-related energy bioaccessibility was 78.5%±3.1%, with an average energy loss of 21.2%±3.1% (40.6 kcal/d in the full-dose almond phase). Bioaccessibility of energy and fat from the diet as a whole was significantly less with almond consumption (in both half- and full-dose phases) compared with the control. Bioaccessibility of fat was significantly different between treatment phases (P<.001) and on average lower by 5.1% and 6.3% in the half- and full-dose almond phases, respectively, compared with the control phase. Energy bioaccessibility was significantly different between the treatment phases (P=.02), decreasing by approximately 2% with the inclusion of the full dose of almonds compared with the control.

CONCLUSION

Energy content of almonds may not be as bioaccessible in individuals with hyperlipidemia as predicted by Atwater factors, as suggested by the increased fat excretion with almond intake compared with the control.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00507520.

The impact of starchy food structure on postprandial glycemic response and appetite: a systematic review with meta-analysis of randomized crossover trials

BACKGROUND

Starchy foods can have a profound effect on metabolism. The structural properties of starchy foods can affect their digestibility and postprandial metabolic responses, which in the long term may be associated with the risk of type 2 diabetes and obesity.

OBJECTIVES

This systematic review sought to evaluate the clinical evidence regarding the impact of the microstructures within starchy foods on postprandial glucose and insulin responses alongside appetite regulation.

METHODS

A systematic search was performed in the PUBMED, Ovid Medicine, EMBASE, and Google Scholar databases for data published up to 18 January 2021. Data were extracted by 3 independent reviewers from randomized crossover trials (RCTs) that investigated the effect of microstructural factors on postprandial glucose, insulin, appetite-regulating hormone responses, and subjective satiety scores in healthy participants.

RESULTS

We identified 745 potential articles, and 25 RCTs (n = 369 participants) met our inclusion criteria: 6 evaluated the amylose-to-amylopectin ratio, 6 evaluated the degree of starch gelatinization, 2 evaluated the degree of starch retrogradation, 1 studied starch-protein interactions, and 12 investigated cell and tissue structures. Meta-analyses showed that significant reductions in postprandial glucose and insulin levels was caused by starch with a high amylose content [standardized mean difference (SMD) = -0.64 mmol/L*min (95% CI: -0.83 to -0.46) and SMD = -0.81 pmol/L*min (95% CI: -1.07 to -0.55), respectively], less-gelatinized starch [SMD = -0.54 mmol/L*min (95% CI: -0.75 to -0.34) and SMD = -0.48 pmol/L*min (95% CI: -0.75 to -0.21), respectively], retrograded starch (for glucose incremental AUC; SMD = -0.46 pmol/L*min; 95% CI: -0.80 to -0.12), and intact and large particles [SMD = -0.43 mmol/L*min (95% CI: -0.58 to -0.28) and SMD = -0.63 pmol/L*min (95% CI: -0.86 to -0.40), respectively]. All analyses showed minor or moderate heterogeneity (I2 < 50%). Sufficient evidence was not found to suggest how these structural factors influence appetite.

CONCLUSIONS

The manipulation of microstructures in starchy food may be an effective way to improve postprandial glycemia and insulinemia in the healthy population. The protocol for this systematic review and meta-analysis was registered in the international prospective register of systematic reviews (PROSPERO) as CRD42020190873.

The effect of a bread matrix on mastication of hazelnuts

The effect of the degree of nut mastication on bioavailability of their nutrients has been established previously. In contrast, the effect of incorporation of nuts into composite food matrixes on oral processing behaviour and structural breakdown has been studied scarcely. This study aimed to investigate the effect of incorporation of hazelnuts into bread matrixes in comparison with plain hazelnuts on bolus properties and chewing behaviour. Amount of plain hazelnuts was varied to investigate the effect of portion size on bolus properties and chewing behaviour. Bolus particle size distribution was obtained by image analysis of expectorated boli by n = 20 participants. Median bolus particle diameter (d₅₀) and broadness of particle size distribution (b) were quantified by fitting the cumulative area distribution curve with a modified Rosin-Rammler function. Oral processing behaviour (number of chews, chewing time, chewing frequency) was quantified by means of a stopwatch. Mastication of two hazelnuts resulted in smaller d₅₀ than mastication of six hazelnuts or mastication of two hazelnuts in white bread or baguette. Chewing time of two hazelnuts was significantly shorter than chewing time of six hazelnuts or chewing time of two hazelnuts in white bread or baguette, while chewing frequency did not differ between foods. d₅₀ of six hazelnuts did not significantly differ from d₅₀ of two hazelnuts in either bread matrix. Broadness b of the particle size distribution was significantly smaller for six hazelnuts compared to the other foods. We conclude that d₅₀ was affected by bite size or bite volume rather than by incorporation of hazelnuts into bread. We suggest that incorporation of hazelnuts into bread matrixes has a relatively small impact on size of hazelnut bolus particles produced upon mastication.

Insights into the starch gelatinization behavior inside intact cotyledon cells

In this work, detailed structural changes of starch within intact cotyledon cells during differential scanning calorimetry (DSC) heating (water: cells ratio of 4:1, v/w) were investigated. Intact cotyledon cells containing raw starch granules from three legumes were isolated and used as materials, followed by simulate DSC heating up to different designated temperatures based on those gelatinization profiles of cells. The swelling power, solubility and gelatinization transition parameters of raw cells were significantly lower than pure starches. Upon simulate heating, all the starches inside intact cells were considered to maintain more amounts of crystalline and double-helix structures than pure starch counterparts. Meanwhile, the starch granules were not completely disrupted even heating up to 15 °C above conclusion temperature (T_c + 15 °C) for intact cells. The results showed clearly that the presence of intact cell wall exerts significant retarding or restricting effects on the process of starch gelatinization.

Symposium 'understanding and managing satiety: processes and opportunities'

This brief report summarises a framework for understanding satiety presented at the 13th European Nutrition Conference, FENS 2019 – Malnutrition in an Obese World: European Perspectives. Aspects of satiety phenotyping and role of food hedonics in satiation are considered in the context of appetite control and obesity. Almonds are evaluated for their unique composition and structure which affect their behaviour in the human gastrointestinal tract. Their role in appetite control and management of satiety has been explored.

In a nutshell: prospects and challenges on coatings for edible kernels

Edible kernels have been popular food items since ancient times. Although in-shell nuts are naturally protected and relatively shelf stable, convenience demands require their commercialization in shelled form. However, whereas shelled kernels are more convenient, they are more exposed to oxygen, and thus more susceptible to oxidative rancidity and loss of crunchiness, which negatively affect the product acceptability. In this review, we discuss the role of edible coatings in extending stability of edible kernels, which is an opportunity to be better explored by the industry. The discussion also includes the role of antioxidants in the context of active coatings. Finally, future prospects and research challenges are addressed. © 2019 Society of Chemical Industry.

Interactions of bile salts with a dietary fibre, methylcellulose, and impact on lipolysis

Methylcellulose (MC) has a demonstrated capacity to reduce fat absorption, hypothetically through bile salt (BS) activity inhibition. We investigated MC cholesterol-lowering mechanism, and compared the influence of two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), which differ slightly by their architecture and exhibit contrasting functions during lipolysis. BS/MC bulk interactions were investigated by rheology, and BS behaviour at the MC/water interface studied with surface pressure and ellipsometry measurements. In vitro lipolysis studies were performed to evaluate the effect of BS on MC-stabilised emulsion droplets microstructure, with confocal microscopy, and free fatty acids release, with the pH-stat method. Our results demonstrate that BS structure dictates their interactions with MC, which, in turn, impact lipolysis. Compared to NaTC, NaTDC alters MC viscoelasticity more significantly, which may correlate with its weaker ability to promote lipolysis, and desorbs from the interface at lower concentrations, which may explain its higher propensity to destabilise emulsions.

Almonds (Prunus Dulcis Mill. D. A. Webb): A Source of Nutrients and Health-Promoting Compounds

Almonds (Prunus dulcis Miller D. A. Webb (the almond or sweet almond)), from the Rosaceae family, have long been known as a source of essential nutrients; nowadays, they are in demand as a healthy food with increasing popularity for the general population and producers. Studies on the composition and characterization of almond macro- and micronutrients have shown that the nut has many nutritious ingredients such as fatty acids, lipids, amino acids, proteins, carbohydrates, vitamins and minerals, as well as secondary metabolites. However, several factors affect the nutritional quality of almonds, including genetic and environmental factors. Therefore, investigations evaluating the effects of different factors on the quality of almonds were also included. In epidemiological studies, the consumption of almonds has been associated with several therapeutically and protective health benefits. Clinical studies have verified the modulatory effects on serum glucose, lipid and uric acid levels, the regulatory role on body weight, and protective effects against diabetes, obesity, metabolic syndrome and cardiovascular diseases. Moreover, recent researchers have also confirmed the prebiotic potential of almonds. The present review was carried out to emphasize the importance of almonds as a healthy food and source of beneficial constituents for human health, and to assess the factors affecting the quality of the almond kernel. Electronic databases including PubMed, Scopus, Web of Science and SciFinder were used to investigate previously published articles on almonds in terms of components and bioactivity potentials with a particular focus on clinical trials.

Energy extraction from nuts: walnuts, almonds and pistachios

The bioaccessibility of fat has implications for satiety and postprandial lipidaemia. The prevailing view holds that the integrity of plant cell wall structure is the primary determinant of energy and nutrient extraction from plant cells as they pass through the gastrointestinal (GI) tract. However, comparisons across nuts (walnuts, almonds and pistachios) with varying physical properties do not support this view. In the present study, masticated samples of three nuts from healthy adults were exposed to a static model of gastric digestion followed by simulated intestinal digestion. Primary outcomes were particle size and lipid release at each phase of digestion. Walnuts produced a significantly larger particle size post-mastication compared with almonds. Under gastric and intestinal conditions, the particle size was larger for walnuts compared with pistachios and almonds (P < 0·05). However, the masticated and digesta particle sizes were not related to the integrity of cell walls or lipid release. The total lipid release was comparable between nuts after the in vitro intestinal phase (P > 0·05). Microstructural examination showed ruptured and fissured cell walls that would allow digestion of cellular contents, and this may be governed by internal cellular properties such as oil body state. Furthermore, the cell walls of walnuts tend to rupture rather than separate and as walnut tissue passes through the GI tract, lipids tend to coalesce reducing digestion efficiency.

Plant Cell Walls: Impact on Nutrient Bioaccessibility and Digestibility

Cell walls are important structural components of plants, affecting both the bioaccessibility and subsequent digestibility of the nutrients that plant-based foods contain. These supramolecular structures are composed of complex heterogeneous networks primarily consisting of cellulose, and hemicellulosic and pectic polysaccharides. The composition and organization of these different polysaccharides vary depending on the type of plant tissue, imparting them with specific physicochemical properties. These properties dictate how the cell walls behave in the human gastrointestinal tract, and how amenable they are to digestion, thereby modulating nutrient release from the plant tissue. This short narrative review presents an overview of our current knowledge on cell walls and how they impact nutrient bioaccessibility and digestibility. Some of the most relevant methods currently used to characterize the food matrix and the cell walls are also described.

Food material properties as determining factors in nutrient release during human gastric digestion: a review

The fundamental mechanisms of nutrient release from solid foods during gastric digestion consists of multiple elementary processes. These include the diffusion of gastric juice into the food matrix and its simultaneous enzymatic degradation and mechanical breakdown by the peristaltic activity of the stomach. Understanding the relative role of these key processes, in association with the composition and structure of foods, is of paramount importance for the design and manufacture of novel foods possessing specific target behavior within the body. This review covers the past and current literature with respect to the in-stomach processes leading to physical and biochemical disintegration of solid foods and release of nutrients. The review outlines recent progress in experimental and modeling methods used for studying food disintegration mechanisms and concludes with a discussion on potential future research directions in this field. Information from pharmaceutical science-based modeling approaches describing nutrient release kinetics as a result of food disintegration in the gastric environment is also reviewed. Future research aimed at understanding gastric digestion is important not only for setting design principles for novel food design but also for understanding mechanisms underpinning dietary guidelines to consume wholesome foods.

Human gastrointestinal conditions affectin vitrodigestibility of peanut and bread proteins

Peanut and wheat proteins either isolated or within the food matrix were subjected to different staticin vitrodigestion models (infant, fed and fasted adult). Proteolysis differed across models.

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.

Effect of process-induced common bean hardness on structural properties of in vivo generated boluses and consequences for in vitro starch digestion kinetics

In the present study, we evaluated the effect of process-induced common bean hardness on structural properties of in vivo generated boluses and the consequences for in vitro starch digestion. Initially, the impact of human mastication on the particle size distribution (PSD) of oral boluses from common beans with different process-induced hardness levels was investigated through a mastication study. Then the effect of structural properties of selected boluses on in vitro starch digestion kinetics was assessed. For a particular process-induced hardness level, oral boluses had similar PSD despite differences in masticatory parameters between participants of the mastication study. At different hardness levels, a clear effect of processing (P<0·0001) was observed. However, the effect of mastication behaviour (P=0·1141) was not significant. Two distinctive fractions were present in all boluses. The first one was a cotyledon-rich fraction consisting of majorly small particles (40-125 µm), which could be described as individual cells based on microscopic observations. This fraction increased with a decrease in process-induced hardness. The second fraction (>2000 µm) mostly contained seed coat material and did not change based on hardness levels. The in vitro starch digestion kinetics of common bean boluses was only affected by process-induced hardness. After kinetic modelling, significant differences were observed between the reaction rate constant of boluses generated from the hardest beans and those obtained from softer ones. Overall this work demonstrated that the in vitro nutritional functionality of common beans is affected to a greater extent by structural properties induced by processing than by mechanical degradation in the mouth.

Insoluble dietary fiber does not affect the ability of phytase to release phosphorus from phytate in the diet of nursery pigs1

Phytase is added to swine diets to improve the utilization of phytate-bound P in swine diets. This provides financial and environmental benefits to the pig industry. However, it is unclear if phytase works equally well in all dietary circumstances. The objective of this experiment was to determine if insoluble fiber affects the efficacy of the phytase enzyme in nursery pigs when fed diets limiting in P content. A total of 480 pigs (initial BW 5.48 ± 0.14 kg) were blocked by BW and randomly assigned (10 pigs per pen) to treatment within the block. A common nutrient-adequate diet was fed from days -14 to -5, and two basal P deficient diets (either a corn-soy diet containing 0.16% standardized total tract digestible [STTD] P [low insoluble fiber [LF]], or a corn-soybean meal plus 20% corn bran containing 0.14% STTD P [high insoluble fiber [HF]]) were fed from days -5 to 0 to acclimate pigs to a P deficient diet. From days 0 to 21, pigs received eight dietary treatments (six pens per treatment: n = 6). Experimental diets consisted of LF supplemented with one of four levels of added phytase (0, 109, 218, and 327 phytase units [FTU]/kg; Quantum Blue 5 G, AB Vista, Wiltshire, United Kingdom) expected to provide 0.16, 0.21, 0.26, and 0.31% STTD P, respectively, or HF supplemented with one of the same four levels of added phytase expected to provide 0.14, 0.19, 0.24, and 0.29% STTD P. Titanium dioxide was added to the diet at 0.4% as an indigestible marker. On day 21, one pig representing the average BW for each pen was euthanized, and fibulae were collected and analyzed for bone ash. Fecal samples were collected from each pen on days 19-20. Data were analyzed using PROC MIXED of SAS. There were no interactions between insoluble fiber and phytase for any of the variables evaluated. For days 0-21, adding phytase increased ADG (P < 0.001) with the response being linear (P < 0.001), whereas insoluble fiber decreased ADG (P = 0.033). There were no effects of phytase or insoluble fiber on ADFI (P = 0.381 and P = 0.632, respectively). Phytase improved G:F ratio (P < 0.001) with the response being linear (P < 0.001). Insoluble fiber tended to decrease G:F ratio (P = 0.097). Phytase increased bone ash (P = 0.005) with the response being linear (P = 0.001), but there was no effect of insoluble fiber (P = 0.949). Phytase did not affect the apparent total tract digestibility of DM, NDF, or ADF (P > 0.050), whereas insoluble fiber decreased the ATTD of DM (P < 0.001), NDF (P < 0.001), and ADF (P < 0.001). In conclusion, the addition of insoluble fiber did not affect the ability of phytase to improve growth performance and bone mineralization in nursery pigs fed a P deficient diet.

An integrated look at the effect of structure on nutrient bioavailability in plant foods

The true bioavailability of a nutrient being intrinsically coupled to the specific food matrix in which it occurs remains poorly considered in nutrition science. During digestion, the food matrix and, in particular, the structure of food modulate the extent and kinetics to which nutrients and bioactive compounds make themselves available for absorption. In this perspective, we describe an integrated look at the effect of structure on nutrient bioavailability in plant foods. Based on this integrated look, cell wall integrity and the particle size of the plant material during its transit in the small intestine determine the bioavailability of plant nutrients; in turn, cell wall integrity and particle size are determined by the level of oral processing and, accordingly, what subsequently escapes digestion in the upper intestine and is utilized by colon microbiota. Ultimately, the effect on nutrient digestion is linked to food structure through each step of digestion. A consideration of the structure rather than just the composition of foods opens up possibilities for the design of healthier foods. © 2018 Society of Chemical Industry.

Fatty acid bioaccessibility and structural breakdown fromin vitrodigestion of almond particles

In vitrogastric digestion of almond particles using a model with simulated peristaltic contractions resulted in particle size reduction and higher fatty acid bioaccessibility thanin vitrodigestion using a model that lacked peristaltic contractions.

Metabolizable Energy from Cashew Nuts is Less than that Predicted by Atwater Factors

Recent studies have demonstrated that the energy provided by several tree nuts is less than that predicted by the Atwater factors, though energy available from cashews has never been assessed. The objective of this study was to evaluate the metabolizable energy in cashew nuts. Eighteen healthy adults were enrolled in a randomized, crossover study with two treatment periods. Subjects were fed a fully controlled base diet for 4 weeks with either no additions or with the addition of 42 g/day (1.5 servings) of cashew nuts, with the final treatment diets being isocaloric. Complete diet collections were analyzed for nitrogen (for protein), fat, energy, and carbohydrate by difference. During the final week of each intervention phase, subjects collected all feces and urine produced, and these were also analyzed for nitrogen (feces and urine), energy (feces and urine), and fat (feces). The resulting data were used to calculate the metabolizable energy of cashews and the digestibility of macronutrients. The average available energy (calorie) content of a 28 g serving of cashew nuts was 137 kcal (±3.4 kcal SEM) and ranged from 105 to 151 kcal. The mean value of 137 kcal/serving is 16% lower (p < 0.0001) than what is typically found on food labels. Digestibility of energy, fat, protein, and carbohydrate was lower for the cashew-containing diet compared to the control diet (92.9% vs. 94.9%, p < 0.0001 for energy; 96.1% vs. 97.8%, p = 0.0009 for fat; 90.1% vs. 91.2%, p = 0.0012 for protein; 92.9% vs. 94.9%, p < 0.0001 for carbohydrate; for the cashew-containing diet vs. the control diet, respectively). In conclusion, cashews provide fewer calories than the values predicted by the Atwater factors, as found on current food labels.

Effect of nuts on energy intake, hunger, and fullness, a systematic review and meta-analysis of randomized clinical trials

Despite high energy content, nut consumption has not been associated with weight gain in epidemiological and clinical investigations. Since a satiety effect a decreased sense of hunger in the following meals has been proposed as the mechanism of nuts against obesity, the present meta-analysis was performed to examine how nut consumption affects "energy intake", "hunger", and "fullness". "Weight" was not included among the search terms but weight data were extracted from the collected articles in order to help interpreting the results. A total of 1048 trials were found, of which 31 passed the eligibility process. Daily energy intake was mostly assessed by 3-day food records, and hunger and fullness were estimated by visual analog scale (VAS). Nut consumption was associated with increased energy intake (mean difference (MD) (nuts - control) = 76.3 kcal; 95% CI: 22.7, 130 kcal; P = 0.005). In contrast, hunger suppressed following nut consumption (MD = -6.54 mm VAS; 95% CI: -12.7, -0.42 mm VAS; P = 0.03). Nuts did not affect sense of fullness and weight in the overall estimate. Subgroup analysis based on participants' BMI revealed that energy intake of overweight/obese individuals was increased following nut consumption while such effect was not observed in normal weight participants. In conclusion, pooled estimates of available clinical trials showed increased energy intake following nut consumption in overweight/obese individuals but not in persons with normal weight. Nut consumption was associated with decreased hunger but no effect was observed on fullness and weight.

Perspective: Reductionist Nutrition Research Has Meaning Only within the Framework of Holistic and Ethical Thinking

Today, it seems that nutrition is in a state of great confusion, especially for the general public. For decades, some nutrients (e.g., cholesterol, saturated fats, sugars, gluten, salt) and food groups (e.g., dairy, cereals, meats) have been regularly denigrated. In this position paper, we hypothesize that such a state of confusion is mainly the result of the reductionist paradigm applied to nutrition research for more than a century, and by being pushed to its extreme, this perspective has led to accusations about some nutrients and foods. However, the real issue is about foods taken as a whole and therefore about their degree of processing, which affects both the food matrix and composition. Indeed, we eat whole foods, not nutrients. Therefore, the objectives of this article are to emphasize the need for more holistic approaches in nutrition to preserve our health, animal welfare, and planet. We propose to first redefine the food health potential on a holistic basis and then to show that reductionism and holism are interconnected approaches that should coexist. Then, we try to explain how extreme reductionism has been disconnected from reality and ethical considerations and has ultimately led to environmental degradation and loss of biodiversity, notably through very specific crops, and to an increased prevalence of chronic diseases. Furthermore, to address the confusion of the general public and to simplify nutritional messages, we propose 3 holistic golden rules based on scientific evidence to protect human health, animal welfare, and the environment (climate and biodiversity). Finally, we try to show how these 3 rules can be easily applied worldwide while respecting the environment, cultural traditions, and heritage.

Influence of oat components on lipid digestion using an in vitro model: Impact of viscosity and depletion flocculation mechanism

Depletion flocculation is a well-known instability mechanism that can occur in oil-in-water emulsions when the concentration of non-adsorbed polysaccharide exceeds a certain level. This critical flocculation concentration depends on the molecular characteristics of the polysaccharide molecules, such as their molecular weight and hydrodynamic radius. In this study, a range of analytical methods (dynamic shear rheology, optical microscopy, and static light-scattering) were used to investigate the interaction between lipid droplets and polysaccharides (guar gum and β-glucans) of varying weight-average molecular weight and hydrodynamic radius, and concentration. The aim of this work was to see if the health benefits of soluble fibers like β-glucans could be explained by their influence on the structure and digestibility of lipid emulsions. The apparent viscosity of the emulsions increased with increasing polysaccharide concentration, molecular weight, and hydrodynamic radius. Droplet flocculation was observed in the emulsions only at certain polysaccharide concentrations, which was attributed to a depletion effect. In addition, the water-soluble components in oat flakes, flour, and bran were extracted using aqueous solutions, to examine their impact on emulsion stability and properties. Then, the rate and extent of lipolysis of a sunflower oil-in-water emulsion in the presence of these oat extracts were monitored using the pH-stat method. However, the inhibition of lipolysis was not linearly related to the viscosity of the oat solutions. The water-soluble extracts of β-glucan collected from oat flakes had a significant inhibitory effect on lipolysis. The results of this study increase our understanding of the possible mechanisms influencing the impact of oat constituents on lipid digestion. This work also highlights the importance of considering the molecular properties of polysaccharides, and not just their impact on solution viscosity.

In vitro lipid digestion in raw and roasted hazelnut particles and oil bodies

Previous studies have proved that the physical encapsulation of nutrients by the cell walls of plant foods modulates macronutrient bioaccessibility during human digestion. In this study, we investigated structural factors that modulate lipid hydrolysis during in vitro digestion of raw and roasted hazelnut particles and isolated oil bodies. Isolated oil bodies exhibited a significantly higher lipid hydrolysis compared to hazelnut particles. Moreover, roasting had an impact on the structure of hazelnut cell walls implying a more efficient diffusion of digestive fluids and enzymes into the hazelnut cells. Heat treatment also caused destabilization of oil body interfacial protein membranes, facilitating their proteolysis under gastric conditions, altering the emulsion properties and enhancing fatty acid release during intestinal digestion. This study underlined the barrier role played by the plant cell wall as well as the impact of heat processing on lipid bioaccessibility in hazelnuts.

Characterization of the Degree of Food Processing in Relation With Its Health Potential and Effects

Up today technological processes are intended to produce safe and palatable food products. Yet, it is also expected that processing produces healthy and sustainable foods. However, due to the dramatic increase of chronic diseases prevalence worldwide, i.e., obesity, type 2 diabetes, cardiovascular diseases, and some cancers, ultraprocessing has been pointed out as producing unhealthy foods, rich in energy and poor in protective micronutrients and fiber, i.e., "empty" calories. Indeed the 1980s saw massive arrivals of ultraprocessed foods in supermarkets, i.e., fractionated-recombined foods with added ingredients and/or additives. Epidemiological studies clearly emphasized that populations adhering the most to ultraprocessed foods, e.g., processed meat, refined grains, ultraprocessed plant-based foods, and/or sweetened beverages, exhibited the higher prevalence of chronic diseases. This prompted researchers to classify foods according to their degree of processing as with the international NOVA classification (i.e., un/minimally processed, processed, and ultraprocessed foods). More and more studies showed that such a classification makes sense for health. Overall one distinguishes three categories of processes: mechanical, thermal, and fermentative treatments, this latter being the more favorable to food health potential. This chapter has therefore several ambitions: (1) to review association between degree of food processing and chronic disease risk prevalence; (2) to explore the impact of technological processes on food health potential considering both matrix and compositional effects; (3) to discuss the need for classifying food according to their degree of processing in future epidemiological studies; and (4) to analyze consequences of adhering to a more holistic paradigm in both food processing and nutrition.

Processing of oat: the impact on oat's cholesterol lowering effect

Epidemiological and interventional studies have clearly demonstrated the beneficial impact of consuming oat and oat-based products on serum cholesterol and other markers of cardiovascular disease. The cholesterol-lowering effect of oat is thought to be associated with the β-glucan it contains. However, not all food products containing β-glucan seem to lead to the same health outcome. Overall, highly processed β-glucan sources (where the oat tissue is highly disrupted) appear to be less effective at reducing serum cholesterol, but the reasons are not well understood. Therefore, the mechanisms involved still need further clarification. The purpose of this paper is to review current evidence of the cholesterol-lowering effect of oat in the context of the structure and complexity of the oat matrix. The possibility of a synergistic action and interaction between the oat constituents promoting hypocholesterolaemia is also discussed. A review of the literature suggested that for a similar dose of β-glucan, (1) liquid oat-based foods seem to give more consistent, but moderate reductions in cholesterol than semi-solid or solid foods where the results are more variable; (2) the quantity of β-glucan and the molecular weight at expected consumption levels (∼3 g day-1) play a role in cholesterol reduction; and (3) unrefined β-glucan-rich oat-based foods (where some of the plant tissue remains intact) often appear more efficient at lowering cholesterol than purified β-glucan added as an ingredient.

Understanding the Effect of Particle Size and Processing on Almond Lipid Bioaccessibility through Microstructural Analysis: From Mastication to Faecal Collection

We have previously reported on the low lipid bioaccessibility from almond seeds during digestion in the upper gastrointestinal tract (GIT). In the present study, we quantified the lipid released during artificial mastication from four almond meals: natural raw almonds (NA), roasted almonds (RA), roasted diced almonds (DA) and almond butter from roasted almonds (AB). Lipid release after mastication (8.9% from NA, 11.8% from RA, 12.4% from DA and 6.2% from AB) was used to validate our theoretical mathematical model of lipid bioaccessibility. The total lipid potentially available for digestion in AB was 94.0%, which included the freely available lipid resulting from the initial sample processing and the further small amount of lipid released from the intact almond particles during mastication. Particle size distributions measured after mastication in NA, RA and DA showed most of the particles had a size of 1000 µm and above, whereas AB bolus mainly contained small particles (<850 µm). Microstructural analysis of faecal samples from volunteers consuming NA, RA, DA and AB confirmed that some lipid in NA, RA and DA remained encapsulated within the plant tissue throughout digestion, whereas almost complete digestion was observed in the AB sample. We conclude that the structure and particle size of the almond meals are the main factors in regulating lipid bioaccessibility in the gut.

Food processing and structure impact the metabolizable energy of almonds

The measured metabolizable energy (ME) of whole almonds has been shown to be less than predicted by Atwater factors. However, data are lacking on the effects of processing (roasting, chopping or grinding) on the ME of almonds. A 5-period randomized, crossover study in healthy individuals (n = 18) was conducted to measure the ME of different forms of almonds (42 g per day), as part of a controlled diet: whole, natural almonds; whole, roasted almonds; chopped almonds; almond butter; and control (0 g per day). After 9 days of adaptation to each diet, participants collected all urine and fecal samples for 9 days. Diets, urine, and feces were analyzed to determine ME. Fracture force and fracture properties of whole and chopped almonds were measured. Measured ME (kcal g^-1) of whole natural almonds (4.42), whole roasted almonds (4.86), and chopped almonds (5.04) was significantly lower than predicted with Atwater factors (P < 0.001); ME of almond butter (6.53 kcal g^-1) was similar to predicted (P = 0.08). The ME of whole roasted and chopped almonds was lower than almond butter (P < 0.0001). ME of whole natural almonds was lower than whole roasted almonds (P < 0.05). This may be due to lower hardness of whole roasted (298 ± 1.3 N) compared to whole natural almonds (345 ± 1.6 N) (P < 0.05), and to whole natural almonds fracturing into fewer, larger particles, thus inhibiting the release of lipids. Atwater factors overestimate the ME of whole (natural and roasted) and chopped almonds. The amount of calories absorbed from almonds is dependent on the form in which they are consumed.

The impact of oat structure and β-glucan on in vitro lipid digestion

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The structure of oat tissue is an important factor for determining its influence on (in vitro) lipid digestion.

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β-glucan release from oat cell walls during digestion was not complete.

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Processing of oats affects the rate and extent of lipolysis.

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Viscosity is not the only factor affecting lipolysis.

Oat β-glucan has been shown to play a positive role in influencing lipid and cholesterol metabolism. However, the mechanisms behind these beneficial effects are not fully understood.

The purpose of the current work was to investigate some of the possible mechanisms behind the cholesterol lowering effect of oat β-glucan, and how processing of oat modulates lipolysis. β-Glucan release, and the rate and extent of lipolysis measured in the presence of different sources of oat β-glucan, were investigated during gastrointestinal digestion.

Only a fraction of the original β-glucan content was released during digestion. Oat flakes and flour appeared to have a more significant effect on lipolysis than purified β-glucan.

These findings show that the positive action of β-glucan is likely to involve complex processes and interactions with the food matrix. This work also highlights the importance of considering the structure and physicochemical properties of foods, and not just the nutrient content.

In vitro and in vivo modeling of lipid bioaccessibility and digestion from almond muffins: The importance of the cell-wall barrier mechanism

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We investigated the mechanisms of lipid bioaccessibility from almond muffins.

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An in vitro dynamic gastric model was used to simulate human digestion.

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A pilot ileostomy study was performed to define the rate of lipid release.

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Microstructural analysis proved that some lipid remained encapsulated within matrix.

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The cell-wall is the main factor regulating the lipid bioaccessibility.

This study compares in vitro and in vivo models of lipid digestion from almond particles within a complex food matrix (muffins) investigating whether the cell-wall barrier regulates the bioaccessibility of nutrients within this matrix. Muffins containing small (AF) or large (AP) particles of almond were digested in triplicate using an in vitro dynamic gastric model (DGM, 1 h) followed by a static duodenal digestion (8 h). AF muffins had 97.1 ± 1.7% of their lipid digested, whereas AP muffins had 57.6 ± 1.1% digested. In vivo digestion of these muffins by an ileostomy volunteer (0–10 h) gave similar results with 96.5% and 56.5% lipid digested, respectively. The AF muffins produced a higher postprandial triacylglycerol iAUC response (by 61%) than the AP muffins. Microstructural analysis showed that some lipid remained encapsulated within the plant tissue throughout digestion. The cell-wall barrier mechanism is the main factor in regulating lipid bioaccessibility from almond particles.

Component analysis of nutritionally rich chloroplasts: recovery from conventional and unconventional green plant species

A study of the literature indicates that chloroplasts synthesise a range of molecules, many of which have nutritional value for humans, but the nutritional credentials of chloroplasts recovered from plant cells are not established. Chloroplast-rich-fractions (CRFs) were prepared from green plant species and the macro- and micro-nutrient composition compared with the whole leaf materials (WLMs). The results indicated that, on a dry weight basis, CRF material from a range of green biomass was enriched in lipids and proteins, and in a range of micronutrients compared with the WLM. Vitamins E, pro-vitamin A, and lutein were all greater in CRF preparations. Of the minerals, iron was most notably concentrated in CRF. Spinach CRFs possessed the highest α-tocopherol [62 mg 100 g^-1, dry weight (DW)], β-carotene (336 mg 100 g^-1 DW) and lutein (341 mg 100 g^-1 DW) contents, whilst grass CRFs had the highest concentration of alpha-linolenic acid (ALA) (69.5 mg g^-1). The higher concentrations of α-tocopherol, β-carotene, lutein, ALA and trace minerals (Fe and Mn) in CRFs suggested their potential use as concentrated ingredients in food formulations deficient in these nutrients.