Postprandial lipid and vascular responses following consumption of a commercially-relevant interesterified palmitic acid-rich spread in comparison to functionally-equivalent non-interesterified spread and spreadable butter: a randomised controlled trial in healthy adults.

Background: Interesterification is an industrial processing technique used widely where hard fats are essential for functionality and consumer acceptability, e.g. margarines and lower fat spreads. Objective: The aim of this study was to compare acute cardiovascular effects of functionally equivalent spreads (similar solid fat content) made with interesterified (IE) or non-IE palm-based fats, or spreadable butter. Methods: A randomised, controlled, 4-armed crossover, double-blind study (25 men, 25 women; 35-75 years; healthy; mean BMI 24.5, SD 3.8), compared effects of mixed nutrient meals containing 50 g fat from functionally equivalent products [IE spread, non-IE spread and spreadable butter (SB), with rapeseed oil (RO) as a reference treatment: with 16.7%, 27.9%, 19.3% and 4% palmitic acid, respectively] on 8 h postprandial changes in plasma triacylglycerol (TAG) and endothelial dysfunction (flow-mediated dilatation; FMD). Circulating reactive oxygen species (estimated using a neutrophil oxidative burst assay), glucose, insulin, NEFA, lipoprotein particle profiles, inflammatory markers (glycoprotein acetylation (Glyc-A) and IL-6), and biomarkers of endotoxemia were measured. Results: Postprandial plasma TAG concentrations after test meals were similar. However following RO versus the 3 spreads, there were significantly higher postprandial apolipoprotein B concentrations, and small HDL and LDL particle concentrations, and lower postprandial extra-large, large, and medium HDL particle concentrations, as well as smaller average HDL and LDL particle sizes. There were no differences following IE compared to the other spreads. Postprandial FMD% did not decrease after high-fat test meals, and there were no differences between treatments. Postprandial serum IL-6 increased similarly after test meals, but RO provoked a greater increase in postprandial concentrations of glycoprotein acetyls (GlycA), as well as 8 h sCD14, an endotoxemia marker. All other postprandial outcomes were not different between treatments. Conclusions: In healthy adults, a commercially-available IE-based spread did not evoke a different postprandial triacylglycerol, lipoprotein subclass, oxidative stress, inflammatory or endotoxemic response to functionally-equivalent, but compositionally-distinct alternative spreads. Clinical trial registry number: NCT03438084 (https://ClinicalTrials.gov).

Mechanisms of interesterified fat digestibility in a muffin matrix using a dynamic gastric model.

Industrially generated trans-fats have been linked with cardiovascular disease (CVD) and have thus been replaced by interesterified (IE) fats, in foods. Interesterification rearranges fatty acids on the glycerol backbone of a triacylglycerol molecule. However, the impact of IE fat on health is unknown. We recently reported differences in lipid absorption kinetics between IE and rapeseed oil (RO). Here, we investigated the mechanisms underpinning IE fat digestion kinetics in the same muffins baked using an IE fat, non-IE fat [with the same fatty acid composition] and rapeseed oil (RO) under simulated conditions. IE and non-IE fats were largely solid in the gastric phase and strongly associated within the muffin matrix, whereas RO formed liquid droplets which separated from the matrix. No significant difference in lipolysis rates was detected between IE and non-IE fats. The lipolysis of the RO fat was slower, due to long-chain PUFAs. Interesterification itself did not affect digestibility, but the strong interaction between the hard fats and the muffin matrix resulted in extensive creaming of the matrix in the stomach, leading to delayed gastric emptying compared to the RO sample. The rate and extent of lipolysis were determined by the amount of fat available and the structure of the fat. This demonstrates the importance of the physical behaviour of the fats during digestion and provides a mechanistic understanding of the overall lipid digestion of IE fats, which relates to their physiological response.

Palmitic acid-rich oils with and without interesterification lower postprandial lipemia and increase atherogenic lipoproteins compared with a MUFA-rich oil: A randomized controlled trial.

BACKGROUND: Interesterified (IE) fats are widely used in place of trans fats; however, little is known about their metabolism. OBJECTIVES: To test the impact of a commonly consumed IE compared with a non-IE equivalent fat on in vivo postprandial and in vitro lipid metabolism, compared with a reference oil [rapeseed oil (RO)]. METHODS: A double-blinded, 3-phase crossover, randomized controlled trial was performed in healthy adults (n = 20) aged 45-75 y. Postprandial plasma triacylglycerol and lipoprotein responses (including stable isotope tracing) to a test meal (50 g fat) were evaluated over 8 h. The test fats were IE 80:20 palm stearin/palm kernel fat, an identical non-IE fat, and RO (control). In vitro, mechanisms of digestion were explored using a dynamic gastric model (DGM). RESULTS: Plasma triacylglycerol 8-h incremental area under the curves were lower following non-IE compared with RO [-1.7 mmol/L⋅h (95% CI: -3.3, -0.0)], but there were no differences between IE and RO or IE and non-IE. LDL particles were smaller following IE and non-IE compared with RO (P = 0.005). Extra extra large, extra large, and large VLDL particle concentrations were higher following IE and non-IE compared with RO at 6-8 h (P < 0.05). No differences in the appearance of [13C]palmitic acid in plasma triacylglycerol were observed between IE and non-IE fats. DGM revealed differences in phase separation of the IE and non-IE meals and delayed release of SFAs compared with RO. CONCLUSIONS: Interesterification did not modify fat digestion, postprandial lipemia, or lipid metabolism measured by stable isotope and DGM analysis. Despite the lower lipemia following the SFA-rich fats, increased proatherogenic large triacylglycerol-rich lipoprotein remnant and small LDL particles following the SFA-rich fats relative to RO adds a new postprandial dimension to the mechanistic evidence linking SFAs to cardiovascular disease risk.

A natural mutation in Pisum sativum L. (pea) alters starch assembly and improves glucose homeostasis in humans.

Elevated postprandial glucose (PPG) is a significant risk factor for non-communicable diseases globally. Currently, there is a limited understanding of how starch structures within a carbohydrate-rich food matrix interact with the gut luminal environment to control PPG. Here, we use pea seeds (Pisum sativum) and pea flour, derived from two near-identical pea genotypes (BC1/19RR and BC1/19rr) differing primarily in the type of starch accumulated, to explore the contribution of starch structure, food matrix and intestinal environment to PPG. Using stable isotope 13C-labelled pea seeds, coupled with synchronous gastric, duodenal and plasma sampling in vivo, we demonstrate that maintenance of cell structure and changes in starch morphology are closely related to lower glucose availability in the small intestine, resulting in acutely lower PPG and promotion of changes in the gut bacterial composition associated with long-term metabolic health improvements.

Structural stability of liposome-stabilized oil-in-water pickering emulsions and their fate during in vitro digestion.

Most current research on food-relevant Pickering emulsions has been conducted using inorganic or food-compatible organic particles as emulsifiers. A key challenge is maintaining a favourable structure while being able to resist displacement or destabilisation by surfactants and controlling transport of substrates during digestion. Liposome stabilised emulsions have demonstrated some potential for being smart, responsive delivery systems for poorly available bioactives and drugs. We developed a liposome-stabilized oil-in-water Pickering emulsion utilising macromolecular crowding- with polyethylene glycol (PEG). They were pH-controllable and had surfactant-dependent deformability whilst displaying dual delivery routes from both the liposome and oil phases. Dynamic light scattering, confocal microscopy and emulsion stability measurements indicated the liposomes containing 10% PEG at neutral pH remained intact at the interface for extended time. Various degrees of interfacial coverage still existed in the presence of PEG, under acidic environment and with added bile salts. Emulsions with added PEG maintained a more integrated structure after in vitro oral-gastric digestion, and showed greater lipolysis with more free fatty acids (14.7 ± 0.5% for with PEG vs. 12.7 ± 0.1% for without PEG) released during in vitro intestinal digestion. These Pickering emulsions could provide a flexible approach to controlled release under a broad range of conditions.

Fish Oil Emulsions Stabilized with Caseinate Glycated by Dextran: Physicochemical Stability and Gastrointestinal Fate.

Incorporation of fish oil containing ω-3 polyunsaturated fatty acids (PUFAs) into functional foods remains challenging. In this study, caseinate and glycoconjugates (CD6, CD40, CD70, CD100) of caseinate to dextrans of different molecular weights (D6, D40, D70, D100 kDa) were used to stabilize fish oil emulsions, and the impact on physicochemical stability and gastrointestinal fate was investigated. The glycoconjugate of CD6 exhibited significantly higher conjugation efficiency, lower surface hydrophobicity ( H0), and lower surface activity than other glycoconjugates. The glycoconjugate of CD70 displayed the best emulsifying activity and emulsion stability. Except CD6 stabilized emulsions, all other emulsions showed fine storage stability over 14 d at 22 ± 1 °C. The glycoconjugate stabilized emulsions exhibited significantly lower peroxide value (PV) ( P < 0.05) than that of the caseinate stabilized one. During in vitro gastrointestinal tract digestion, the glycation of caseinate with dextrans changed the ζ-potential, average particle size ( D32), and particle size distribution of the emulsions, which influenced flocculation and coalescence of droplets, as demonstrated by confocal microscopy. Caseinate after glycation with dextrans significantly retarded the release of free fatty acids from emulsions ( P < 0.05) during in vitro lipolysis. These results suggested that the dextrans attached to caseinate by glycation played a vital role in physicochemical stability and gastrointestinal fate of emulsions, mainly by its steric hindrance to effectively prevent flocculation and coalescence of droplets.

Intrinsic wheat lipid composition effects the interfacial and foaming properties of dough liquor.

Doughs were prepared from a single variety breadmaking flour (cv. Hereward), from three successive harvests (years; 2011, 2012 and 2013). A preparation of the aqueous phase from dough, known as dough liquor (DL), was prepared by ultracentrifugation and its physico-chemical properties were investigated. Surface tension and interfacial rheology, showed that the interface of DL was lipid-dominated and that 2013 DL had a different type of interface to 2011 and 2012 DL. This data was consistent with the improved foam stability observed for 2013 DL and with the types of lipids identified. All foams collapsed quickly, but the most stable foam was from 2013 DL with 89.2% loss in foam, followed by 2011 DL with 91.7% loss and 2012 had the least stable foam with a loss of 92.5% of the foam structure. Glycolipids (DGDG and MGDG) were enriched in 2013 DL, and were also present in DL foam, contributing towards improved stability. Neutral lipids, such as FFAs, were enriched in DL foams contributing towards instability and rapid foam collapse. Baking trials using 2012 and 2013 flour, showed increased loaf volumes and gas bubble diameter in 2013 bread compared to 2012 bread, highlighting the potential impact that surface active polar lipids, enriched in the aqueous phase of dough, could have on improving breadmaking quality.

Oatmeal particle size alters glycemic index but not as a function of gastric emptying rate.

The aim of this study was to determine the extent to which oat particle size in a porridge could alter glucose absorption, gastric emptying, gastrointestinal hormone response, and subjective feelings of appetite and satiety. Porridge was prepared from either oat flakes or oat flour with the same protein, fat, carbohydrate, and mass. These were fed to eight volunteers on separate days in a crossover study, and subjective appetite ratings, gastric contents, and plasma glucose, insulin, and gastrointestinal hormones were determined over a period of 3 h. The flake porridge gave a lower glucose response than the flour porridge, and there were apparent differences in gastric emptying in both the early and late postprandial phases. The appetite ratings showed similar differences between early- and late-phase behavior. The structure of the oat flakes remained sufficiently intact to delay their gastric emptying, leading to a lower glycemic response, even though initial gastric emptying rates were similar for the flake and flour porridge. This highlights the need to take food structure into account when considering relatively simple physiological measures and offering nutritional guidance.NEW & NOTEWORTHY The impact of food structure on glycemic response even in simple foods such as porridge is dependent on both timing of gastric emptying and the composition of what is emptied as well as duodenal starch digestion. Thus structure should be accounted for when considering relatively simple physiological measures and offering nutritional guidance.

How much is too much? Threshold dose distributions for 5 food allergens.

BACKGROUND: Precautionary labeling is used to warn consumers of the presence of unintended allergens, but the lack of agreed allergen thresholds can result in confusion and risk taking by patients with food allergy. The lack of data on threshold doses below which subjects are unlikely to react is preventing the development of evidence-based allergen management strategies that are understood by clinician and patient alike. OBJECTIVE: We sought to define threshold dose distributions for 5 major allergenic foods in the European population. METHODS: Patients with food allergy were drawn from the EuroPrevall birth cohort, community surveys, and outpatient clinic studies and invited to undergo a food challenge. Low-dose, double-blind, placebo-controlled food challenges were undertaken with commercially available food ingredients (peanut, hazelnut, celery, fish, and shrimp) blinded into common matrices. Dose distributions were modeled by using interval-censoring survival analysis with 3 parametric approaches. RESULTS: Of the 5 foods used for challenge, 4 produced similar dose distributions, with estimated doses eliciting reactions in 10% of the allergic population (ED10), ranging from 1.6 to 10.1 mg of protein for hazelnut, peanut, and celery with overlapping 95% CIs. ED10 values for fish were somewhat higher (27.3 mg of protein), although the CIs were wide and overlapping between fish and plant foods. Shrimp provided radically different dose distributions, with an ED10 value of 2.5 g of protein. CONCLUSION: This evidence base will contribute to the development of reference doses and action levels for allergens in foods below which only the most sensitive subjects might react.

Chicken juice enhances surface attachment and biofilm formation of Campylobacter jejuni.

The bacterial pathogen Campylobacter jejuni is primarily transmitted via the consumption of contaminated foodstuffs, especially poultry meat. In food processing environments, C. jejuni is required to survive a multitude of stresses and requires the use of specific survival mechanisms, such as biofilms. An initial step in biofilm formation is bacterial attachment to a surface. Here, we investigated the effects of a chicken meat exudate (chicken juice) on C. jejuni surface attachment and biofilm formation. Supplementation of brucella broth with ≥5% chicken juice resulted in increased biofilm formation on glass, polystyrene, and stainless steel surfaces with four C. jejuni isolates and one C. coli isolate in both microaerobic and aerobic conditions. When incubated with chicken juice, C. jejuni was both able to grow and form biofilms in static cultures in aerobic conditions. Electron microscopy showed that C. jejuni cells were associated with chicken juice particulates attached to the abiotic surface rather than the surface itself. This suggests that chicken juice contributes to C. jejuni biofilm formation by covering and conditioning the abiotic surface and is a source of nutrients. Chicken juice was able to complement the reduction in biofilm formation of an aflagellated mutant of C. jejuni, indicating that chicken juice may support food chain transmission of isolates with lowered motility. We provide here a useful model for studying the interaction of C. jejuni biofilms in food chain-relevant conditions and also show a possible mechanism for C. jejuni cell attachment and biofilm initiation on abiotic surfaces within the food chain.

Assessment of the sensitizing potential of processed peanut proteins in Brown Norway rats: roasting does not enhance allergenicity.

BACKGROUND: IgE-binding of process-modified foods or proteins is the most common method for examination of how food processing affects allergenicity of food allergens. How processing affects sensitization capacity is generally studied by administration of purified food proteins or food extracts and not allergens present in their natural food matrix. OBJECTIVES: The aim was to investigate if thermal processing increases sensitization potential of whole peanuts via the oral route. In parallel, the effect of heating on sensitization potential of the major peanut allergen Ara h 1 was assessed via the intraperitoneal route. METHODS: Sensitization potential of processed peanut products and Ara h 1 was examined in Brown Norway (BN) rats by oral administration of blanched or oil-roasted peanuts or peanut butter or by intraperitoneal immunization of purified native (N-), heated (H-) or heat glycated (G-)Ara h 1. Levels of specific IgG and IgE were determined by ELISA and IgE functionality was examined by rat basophilic leukemia (RBL) cell assay. RESULTS: In rats dosed orally, roasted peanuts induced significant higher levels of specific IgE to NAra h 1 and 2 than blanched peanuts or peanut butter but with the lowest level of RBL degranulation. However, extract from roasted peanuts was found to be a superior elicitor of RBL degranulation. Process-modified Ara h 1 had similar sensitizing capacity as NAra h 1 but specific IgE reacted more readily with process-modified Ara h 1 than with native. CONCLUSIONS: Peanut products induce functional specific IgE when dosed orally to BN rats. Roasted peanuts do not have a higher sensitizing capacity than blanched peanuts. In spite of this, extract from roasted peanuts is a superior elicitor of RBL cell degranulation irrespectively of the peanut product used for sensitization. The results also suggest that new epitopes are formed or disclosed by heating Ara h 1 without glucose.

Effect of dough mixing on wheat endosperm cell walls.

Dough-derived cell wall fragments isolated by ultracentrifugation were largely derived from the starchy endosperm, with some fragments deriving from the aleurone and outer layers, as indicated by fluorescence microscopy. Dough mixing had little effect on the structure and composition of cell wall fragments compared to thin grain sections, as determined by Fourier transform infrared (FTIR) and (1)H nuclear magnetic resonance (NMR) spectroscopy. These analyses confirmed that the fragments largely comprised water-unextractable arabinoxylan and ß-glucan. FTIR microspectroscopy of dough-derived cell wall fragments prepared from five bread wheat cultivars showed that two largely comprised highly substituted arabinoxylan (cv. Manital and San Pastore), one comprised a mixture of low, medium, and highly substituted arabinoxylan (cv. Hereward), and the remaining two comprised a greater proportion of low substituted arabinoxylan (cv. Claire and Yumai 34). Yumai 34 yielded a greater mass of cell wall material, and its cell walls comprised a high proportion of medium substituted arabinoxylan. Such methods will allow for the impact of bakery ingredients and processing on endosperm cells, including the addition of xylanases, to be investigated in the future to ensure any potential health benefits arising from wheat breeding are realized in the food that reaches the consumer.

Quantification and partial characterization of the residual protein in fully and partially refined commercial soybean oils.

A method has been developed to determine residual protein in refined oils, a potential trigger of allergic reactions. High-pH bicarbonate or borate buffers were found to be the most effective extractants, residual oil protein comprising a mixture of proteins of M(r) 6000-100000. Extracted protein could be quantified with superior precision using 3-(4-carboxybenzoyl)quinolone-2-carboxaldehyde (CBQCA). Residual protein content determined in a set of oils using the borate extraction-CBQCA assay was positively correlated with contents determined using a bicarbonate-total amino acid analysis method. Oil refining substantially reduced the oil protein content determined by the borate-CBQCA assay with neutralized/refined, bleached, and deodorized (fully refined) oils containing 62-265 ng/g oil, whereas crude un-degummed oils contained 86000-87900 ng/g of protein. These analyses and published data on cumulative threshold doses for soybean suggest that even the most sensitive individuals would need to consume at least 50 g of highly refined oil to experience subjective symptoms.

The identification of foam-forming soluble proteins from wheat (Triticum aestivum) dough.

Proteomic methods have been used to identify foam-forming soluble proteins from dough that may play an important role in stabilising gas bubbles in dough, and hence influence the crumb structure of bread. Proteins from a soluble fraction of dough (dough liquor) or dough liquor foam have been separated by two-dimensional gel electrophoresis, and 42 identified using a combination of matrix-assisted laser desorption/ionization-time of flight and quadrupole-time of flight analyses. Major polypeptide components included beta-amylase, tritin and serpins, with members of the alpha-amylase/trypsin inhibitor family being particularly abundant. Neither prolamin seed storage proteins nor the surface-active protein puroindoline were found. Commonly used dough ingredients (NaCl, Na L-ascorbate) had only a minor effect on the 2-DE protein profiles of dough liquor, of which one of the more significant was the loss of 9 kDa nonspecific lipid transfer protein. Many proteins were lost in dough liquor foam, particularly tritin, whilst a number of alpha-amylase inhibitors were more dominant, suggesting that these are amongst the most strongly surface-active proteins in dough liquor. Such proteins may play a role determining the ability of the aqueous phase of doughs, as represented by dough liquor, to form an elastic interface lining the bubbles, and hence maintain their integrity during dough proving.