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Emulsifiers and Hydrocolloids

by luciano

Premise

Hydrocolloids and emulsifiers are both food additives, but they have different functions. Hydrocolloids are substances that thicken, gel or stabilize food, while emulsifiers help mix immiscible substances such as oil and water.

Hydrocolloids

They are substances that, in aqueous solution, form a colloidal system, increasing viscosity or forming gels.

Their main function is to modify the consistency of foods, making them denser, creamier or gelatinous.

They can also stabilize emulsions or suspensions, preventing phase separation.

Some examples of hydrocolloids: agar-agar, modified starches, beta-glucans, carrageenin, pectin, carob seeds, bamboo fibers, potato fibers, pea fibers, gelatins, gum arabic, xanthan gum, guar, inulin. In which products is it easier to find them: bakery and pastry products, biscuits, ice cream, yogurt, sports drinks (especially maltodextrins).

Emulsifiers:

They are molecules that have a hydrophobic part (fat lover) and a hydrophilic part (water lover).

This structure allows them to stabilize emulsions, i.e. mixtures of immiscible liquids such as oil and water.

The emulsifiers are arranged between the two phases, reducing the surface tension and preventing separation.

Common examples include lecithin, mono- and diglycerides of fatty acids and polysorbates.

In summary, while hydrocolloids modify the general consistency of a food, emulsifiers work specifically to keep the emulsions stable, avoiding the separation of oil and water. Some hydrocolloids, such as lecithin, may also have emulsifying properties.

Emulsifiers

Highlighted:
A recent study, published in The Lancet Diabetes & Endocrinology, evaluated for the first time the association between emulsifiers and the risk of developing type 2 diabetes

I – Emulsifiers and diabetes risk: Lancet’s study

Although the Health Authorities consider their use in defined quantities safe, based on criteria of cytotoxicity and genotoxicity, recently, evidence is emerging of their negative effects on the intestinal microbiota, which in turn trigger inflammation and metabolic alterations.

After being accused of contributing to the risk of obesity, cancer and cardiovascular diseases, a recent analysis (Seven emulsifiers incriminated for potential increased risk of type 2 diabetes SID, Italian Society of Diabetology 07-05-2024) conducted on the prospective study of NutriNet Santé cohort identifies them as factors that increase the risk of type 2 diabetes.
The study, published in The Lancet Diabetes & Endocrinology [1] evaluated for the first time the association between emulsifiers and risk of developing type 2 diabetes. The Authors analyzed the data of over 104 thousand adults enrolled from 2009 to 2023 who were asked to fill out 24-hour dietary records every 6 months. The objective was to evaluate the exposure to emulsifiers.
1% of the sample developed type 2 diabetes during the 6-8 year follow-up.

Of the 61 identified additives, seven are ‘attention’ emulsifiers associated with a potential increase in the risk of diabetes (eyes, therefore, on the labels!):

E407 (total carrageenan);
E340 (polyglycerol esters);
E472e (fatty acid esters);
E331 (sodium citrate);
E412 (guar gum);
E414 (gum arabic);
E415 (xanthan gum);

In addition to a group called ‘carrageenine’.

Emulsifier additives were taken in 5% from ultra-processed fruits and vegetables (such as canned vegetables and fruit in syrup), in 14.7% from cakes and biscuits, in 10% from dairy products.

Three consequences highlighted by prof. Angelo Avogaro, President of SID

1. The need to contain the consumption of ultra-processed foods;

2. The call for greater attention to labels;

3. The need to call for stricter regulation in order to protect consumers.

“Although further long-term studies are needed, changes in the intestinal microbiota suggest that RDAs (Recommended Daily Allowance) may need to be reviewed. Previous evidence linking carrageenan intake to intestinal inflammation has led JECFA to limit its use in formulas and infant foods. We are witnessing a worrying increase in type 2 diabetes even among children and adolescents” underlines Prof. Raffaella Buzzetti, President-elect of the ISD.

Notes

[1] Food additive emulsifiers and the risk of type 2 diabetes: analysis of data from the NutriNet-Santé prospective cohort study. The Lancet Diabete and Endocrinology, volume 12, issue 5, p339-349, May 2024.

2 – Direct impact of commonly used dietary emulsifiers on human gut microbiota
Abstract.
Background: Epidemiologic evidence and animal studies implicate dietary emulsifiers in contributing to the increased prevalence of diseases associated with intestinal inflammation, including inflammatory bowel diseases and metabolic syndrome. Two synthetic emulsifiers in particular, carboxymethylcellulose and polysorbate 80, profoundly impact intestinal microbiota in a manner that promotes gut inflammation and associated disease states. In contrast, the extent to which other food additives with emulsifying properties might impact intestinal microbiota composition and function is not yet known.
….omissis.
Conclusions: These results indicate that numerous, but not all, commonly used emulsifiers can directly alter gut microbiota in a manner expected to promote intestinal inflammation. Moreover, these data suggest that clinical trials are needed to reduce the usage of the most detrimental compounds in favor of the use of emulsifying agents with no or low impact on the microbiota. Direct impact of commonly used dietary emulsifiers on human gut microbiota. Sabrine Naimi. et al. Microbiome (2021) 9:66 https://doi.org/10.1186/s40168-020-00996-6

3 – Dietary Emulsifiers Alter Composition and Activity of the Human Gut Microbiota in vitro, Irrespective of Chemical or Natural Emulsifier Origin.
……..omissis
Discussion
We found dietary emulsifiers to significantly alter human gut microbiota toward a composition and functionality with potentially higher pro-inflammatory properties. While donor-dependent differences in microbiota response were observed, our in vitro experimental setup showed these effects to be primarily emulsifierdependent. Rhamnolipids and sophorolipids had the strongest impact with a sharp decrease in intact cell counts, an increased abundance in potentially pathogenic genera-like Escherichia/Shigella and Fusobacterium, a decreased abundance of beneficial Bacteroidetes and Barnesiella, and a predicted increase in flagellar assembly and general motility. The latter was not substantiated through direct measurements, though. The effects were less pronounced for soy lecithin, while chemical emulsifiers P80 and CMC showed the smallest effects. Short chain fatty acid production, with butyrate production, in particular, was also affected by the respective emulsifiers, again in an emulsifier‐ and donordependent manner.

….omissis. One of the most profound impacts of emulsifier treatment toward gut microbiota was the decline in intact microbial cell counts. The degree of microbiome elimination in this study seems comparable to what has been observed for antibiotic treatments (Francino, 2016; Guirro et al., 2019). Since antibiotics are considered detrimental for gut ecology, this may serve as a warning sign with respect to emulsifier usage. Emulsifiers also act as surfactants, which are known for their membrane solubilizing properties (Jones, 1999). The fact that the observed decline in microbial viability was dependent on emulsifier dose and on the emulsifying potential of the supplemented compound, as measured by the aqueous surface tension reduction (Table 1), leads us to conclude that the dietary emulsifiers attack the bacterial cells principally at the level of the cell membrane.

………….omissis. A last important element in the putative health impact from dietary emulsifiers concern’s interindividual variability. An individual’s unique microbiota and metabolism are important determinants of the potential health effects dietary emulsifiers could cause. While the overall effects from the different emulsifiers toward microbiota composition and functionality were quite consistent in our study, important interindividual differences in susceptibility of the microbiota were noted. Understanding what underlying factors and determinants drive this interindividual variability will be crucial to future health risk assessment of novel and existing dietary emulsifiers. Dietary Emulsifiers Alter Composition and Activity of the Human Gut Microbiota in vitro, Irrespective of Chemical or Natural Emulsifier Origin. Lisa Miclotte et al. Front. Microbiol., 05 November 2020. Sec. Microbial Symbioses
Volume 11 – 2020 | https://doi.org/10.3389/fmicb.2020.577474

Low-grade inflammation and the brain

by luciano

“What is inflammation?
We usually talk about “inflammation” in relation to infections and injuries. When the body is infected, the immune cells recognize the ‘non-self’ molecules and produce inflammatory factors, called “cytokines”, to coordinate the fight against the infection. Cytokines signal other immune cells and bring them to the site of infection. Inflammation is clinically assessed by measuring cytokine concentrations or other inflammatory markers in the blood and is used as a sign of infection.
What is low-grade inflammation?
It is a question that remains hard to answer. Low-grade inflammation is usually defined as “the chronic production, but a low-grade state, of inflammatory factors”. Conditions characterized by low-grade inflammation are for instance obesity (1), depression (2) or chronic pain (3). Low-grade inflammation does not come from an infection but several physiological mechanisms are involved. Concentrations of inflammatory factors in these conditions are overall slightly higher than in healthy populations, but still remain in the healthy ranges. It is therefore hard to determine whether a specific patient exhibits “low-grade inflammation” but it can be better defined at the level of a group of patients.
Inflammation and the brain
When we are sick, we often want to sleep, have reduced appetite, prefer to stay home alone, have difficulty concentrating and can be a bit moody. All these feelings and behaviors are induced by cytokines! Indeed, in addition to coordinating the fight against infection in the periphery of the body, cytokines also act in the brain and induce behavioral changes (4). All these behavioral changes are adaptive, with the purpose of limiting the spread of the infection and allowing the body to spare energy in order to fight the infection instead of, say, going out partying with friends.
However, the behavioral effects of cytokines are not always beneficial. When the cytokine signal is too strong or lasts a long time, such as in cancer patients during treatment with cytokines, these effects can become maladaptive and lead to more chronic and pathological behavioral alterations, such as depression (5). Inflammation is therefore one hypothesized contributor to depression (4). One critical difference between infection or cancer therapy and most cases of depression is, however, the level of production of inflammatory factors. Cytokine levels are high during immunotherapy, i.e., “inflammation”, while depression is characterized by a state of “low-grade inflammation”.
The proportion of subjects who suffer from depression is higher in conditions characterized by low-grade inflammation than in the general population. For instance, 20 to 30% of obese individuals suffer from depression while the prevalence in the general population is of 5-10% (6). While psychological factors are highly likely to be involved, we and others investigate the possibility that low-grade inflammation contributes to this psychiatric vulnerability (7). We have notably shown that low-grade inflammation is associated with behavioral changes in obese individuals, such as fatigue (8) or altered cognitive functions (9). One interpretation of this relationship is that the production of inflammatory factors at a low-grade state may be sufficient to induce behavioral alterations and therefore could be one factor participating to the vulnerability to depression.
Low-grade inflammation and chronic pain
The association between low-grade inflammation and behavioral alterations has caused the team of the Behavioral Medicine Pain Treatment Service at the Karolinska University Hospital in Stockholm (Sweden) to wonder whether low-grade inflammation could modulate the efficacy of behavioral treatments for chronic pain. Cognitive and behavioral strategies are indeed the targets of behavioral treatments for chronic pain and low-grade inflammation could prevent the effects of such treatments.
In collaboration with this group, we showed that treatment outcomes were improved in patients with chronic pain and low levels of inflammatory factors while patients with “low-grade inflammation”, i.e., with higher levels of inflammatory markers but still in the healthy range, exhibited less improvement (10).
Although this study was only exploratory, the findings suggest that low-grade inflammation may promote a state of resistance to behavioral treatment for chronic pain and give a potential explanation regarding non-responder patients.
About Julie Lasselin
Dr Julie Lasselin is a “psychoneuroimmunologist”, conducting research assessing the relationships between the brain and the immune system. She got her Ph.D. in 2012 in NutriNeuro in Bordeaux, France. She then has been working as a post-doc at the Department of Clinical Neuroscience (Psychology Division), Karolinska Institute and at the Stress Research Institute, Stockholm University in Stockholm, Sweden. Julie is currently a post-doc in the Institute of Medical Psychology and Behavioral Immunobiology in Essen, Germany and is affiliated to the Karolinska Institute and Stockholm University. Her research focuses on the contribution of inflammation on the development of neuropsychiatric symptoms in vulnerable populations, such as patients suffering from obesity and type 2 diabetes. She carries out both clinical observational studies and experimental studies using the model of administration of lipopolysaccharide (a component of bacterial shell) in humans. She also assesses more specifically the role of inflammation in fatigue and motivational changes, two symptoms that are highly sensitive to inflammation and may explain the psychiatric vulnerability of obese patients.”
References
1. Wellen, K.E. and G.S. Hotamisligil, Obesity-induced inflammatory changes in adipose tissue. J Clin Invest, 2003. 112:1785-8.
2. Dantzer, R., Depression and inflammation: an intricate relationship. Biol Psychiatry, 2012. 71: p. 4-5.
3. Parkitny, L., et al., Inflammation in complex regional pain syndrome: a systematic review and meta-analysis. Neurology, 2013. 80:106-17.
4. Dantzer, R., et al., From inflammation to sickness and depression: when the immune system subjugates the brain. Nat Rev Neurosci, 2008. 9:46-56.
5. Capuron, L. and A.H. Miller, Immune system to brain signaling: neuropsychopharmacological implications. Pharmacol Ther, 2011. 130:226-38.
6. Evans, D.L., et al., Mood disorders in the medically ill: scientific review and recommendations. Biol Psychiatry, 2005. 58:175-89.
7. Capuron, L., J. Lasselin, and N. Castanon, Role of Adiposity-Driven Inflammation in Depressive Morbidity. Neuropsychopharmacology, 2016 (in press).
8. Lasselin, J., et al., Fatigue symptoms relate to systemic inflammation in patients with type 2 diabetes. Brain Behav Immun, 2012. 26:1211-9.
9. Lasselin, J., et al., Low-grade inflammation is a major contributor of impaired attentional set shifting in obese subjects. Brain Behav Immun, 2016. 58:63-68.
10. Lasselin, J., et al., Low-grade inflammation may moderate the effect of behavioral treatment for chronic pain in adults. J Behav Med, 2016. 39:916-24.

The Gut Microbiota and Inflammation: An Overview

by luciano

Highlighted

“Role of the Gut Microbiota in Immunity and Inflammation
Microbes possess a variety of functions that influence their ability to grow and colonise, whilst bringing about downstream effects for the host that may be beneficial or otherwise [61]. Humans are not capable of digesting some components of dietary fibre due to the lack of the required enzymes to break down and harness the energy of these carbohydrates [62]. Certain species of microbes produce specific enzymes that enable fermentation of nutrients into absorbable forms, including that of indigestible carbohydrates into short-chain fatty acids (SCFAs) [62,63]. These SCFAs may have anti-inflammatory and immunomodulatory effects [63]. SCFAs are only a small part of the bigger picture as, in addition to enzymes and other metabolites produced, components of the bacteria themselves, including lipopolysaccharides, cell capsule carbohydrates and other endotoxins, may also be released and result in secondary effects to the host. These effects include maintenance of gut epithelium (and thereby integrity of the gut wall), production of vitamins, and interactions with several key immune system signalling molecules and cells, activating and inhibiting specific responses [1]. In addition to nutrient metabolism, gut microorganisms affect aspects of pharmacokinetics as they carry out drug metabolism [64]. They provide a natural defence against pathogenic species through competition and maintenance of the mucosa. It is through their contact with the immune system that the microorganisms occupying the gut can elicit or prevent inflammation. They may be associated with anti-inflammatory mechanisms, stimulating regulatory cells of the immune system to inhibit inflammation [65]. On the other hand, as bacteria regulate the permeability of the intestines, certain species can promote a “leaky gut”, where metabolites associated with the microbes leave the gut and enter the bloodstream. In response, the body produces cytokines and other mediators, effectively launching an inflammatory response [66]. Similarly, cells within the epithelial tissue of the gut deliver bacterial metabolites to immune cells, promoting inflammation on both a local and systemic scale. The persistence of this condition may lead to subacute or chronic inflammation, which may subsequently drive the development of diseases such as inflammatory bowel disease, diabetes or cardiovascular disease [65].”

Wheat Bran overview part II

by luciano

Impact of wheat bran physical properties and chemical composition on whole grain flour mixing and baking properties. Sviatoslav Navrotskyi, Gang Guo et al. https://doi.org/10.1016/j.jcs.2019.102790

Abstract
Wheat bran can have diverse chemical composition and physical properties. The objective of this study was to determine the associations among physical and chemical properties of bran and the mixing and baking properties of whole wheat flour. Eighty samples of bran were milled into fine (463 μm) and coarse (783 μm) particle size groups and analyzed for water retention capacity, protein, ash, lipoxygenase activity, antioxidant activity, sulfhydryl groups, and extractable phenolics. Brans were mixed with a single refined flour to make reconstituted whole wheat flour and analyzed for mixing and baking quality. Fine particle size samples had larger bread loaf volume, and softer bread texture compared to the coarse samples. Bran protein and extractable phenolics showed positive correlations with dough strength (p < 0.01) and development time (p < 0.01), respectively. Bran ash was positively correlated with dough strength (p = 0.004). Water retention capacity (WRC) of bran was significantly correlated with dough development time (p = 0.002), bread volume (p = 0.002) and initial hardness (p = 0.007) and firmness (p = 0.028). Overall, this study suggested a strong relationship between bran protein, ash, extractable phenolics, and water retention capacity and whole wheat flour functional properties.

Introduction
Whole grain foods are well known for their nutritional benefits (Hemdane et al., 2016a, Hemdane et al., 2016b). Epidemiological studies have shown that whole grain foods decrease the risk of type 2 diabetes, obesity, and heart disease (Cho et al., 2013) These benefits are likely derived from the combination of vitamins, minerals, antioxidants, and dietary fibers that are present in wheat bran.
Despite the health benefits of whole grains, wheat bran (i.e., non-flour components) tends to decrease dough strength and mixing and fermentation tolerance and reduce bread volume and crumb softness (Gajula, 2007). The negative properties of wheat bran are the result of interactions between flour components (mainly gluten) and either chemical components of the bran, such as dietary fibers, phenolics, antioxidants, low molecular weight sulfhydryl compounds, and enzymes (Khalid et al., 2017, Noort et al., 2010), or physical properties of the bran, such as water retention capacity (WRC) and bran particle size (Jacobs et al., 2015).

One of the main contributors to the poor functionality of the whole grain flour are dietary fibers. Dietary fibers generally result in reduced bread volume and poor texture (Mishra, 2016). The negative effects of dietary fibers on bread volume and texture can be by explained in many instances by the competition for water between these carbohydrate polymers and gluten proteins, which causes dough weakening (Rosell et al., 2010).

Antioxidants can interact with gluten proteins by reducing disulfide-sulfhydryl interchange reactions, thus impacting gluten protein aggregation (Huang et al., 2018).
Antioxidant properties of wheat brans are mainly determined by their free, bound and conjugated phenolic content. The role of these phenolic compounds in gluten network formation can be explained by their ability to react with gluten protein sulfhydryl groups or increase the rate of protein sulfhydryl-disulfide interchanges (Han and Koh, 2011).
For instance, the addition of phenolic acids to bread decreases dough mixing time, tolerance, and elasticity and decreases bread volume (Han and Koh, 2011).
Free sulfhydryl compounds, which are concentrated in the bran and germ of the wheat kernel, contribute to considerable dough softening (Noctor et al., 2012).
Among all low molecular weight sulfhydryl compounds present in the wheat kernel, glutathione is the most studied. Glutathione has a negative effect on gluten network development by forming disulfide bonds with cysteine residues of gluten proteins and thus terminating gluten macropolymer formation (Noctor et al., 2012).

Tra tutti i composti sulfidrilici a basso peso molecolare presenti nel chicco di grano, il glutatione è il più studiato. Il glutatione ha un effetto negativo sullo sviluppo della rete del glutine formando legami disolfuro con i residui di cisteina delle protein ​del glutine e interrompendo così la formazione dei macropolimeri del glutine (Noctor et al., 2012).

Finally, bran-associated enzymes have variable effects on bread quality. For example, lipoxygenase (LOX) produces active peroxides that can oxidize glutenin thiol groups and promote gluten macropolymer formation (Bahal et al., 2013). However, LOX can impact the flavor of products by catalyzing hydroperoxidation of polyunsaturated fatty acids, which leads to the formation of grassy or beany off-flavors (Hemdane et al., 2016a, Hemdane et al., 2016b).

Bran composition varies among different wheat lines and growing environments (Hossain et al., 2013, Cai et al., 2014). Additionally, due to the different distribution of chemical components among the bran layers (Hemdane et al., 2016a, Hemdane et al., 2016b), milling performance can significantly influence the chemical composition of bran.

Furthermore, bran particle size also has a significant impact on bread quality (Xu et al., 2018), although contradicting results have been reported. de Kock et al. (1999) reported higher loaf volumes by utilizing coarse bran (1800 μm) compared to fine bran (750 μm), and Noort et al. (2010) showed a linear increase in loaf volume with an increase in bran particle size from 70 to 1000 μm.

Inoltre, anche la dimensione delle particelle di crusca ha un impatto significativo sulla qualità del pane (Xu et al., 2018), sebbene siano stati riportati risultati contraddittori. de Kock et al. (1999) hanno riportato volumi di pane più elevati utilizzando crusca grossolana (1800μm) rispetto alla crusca fine (750μm), e Noort et al. (2010) hanno mostrato un aumento lineare del volume del pane con un aumento della dimensione delle particelle di crusca da 70 a 1000μm

However, Zhang and Moore (1999) reported the largest loaf volumes for samples containing medium particle size bran (415 μm) compared with coarse (609 μm) and fine (278 μm). The conflicting reports could be explained by differences in chemical composition among brans, or by differences in milling and baking techniques used.

The present study was designed to identify the role of chemical and physical properties of wheat bran in the mixing and breadmaking quality of whole wheat flour. Chemical components that were most likely to influence flour functionality were selected, taking into consideration the number of samples analyzed. Ultimately, bran particle size, protein, ash, free sulfhydryl groups, extractable phenolics, antioxidant activity, LOX activity, and WRC were evaluated, with dietary fiber evaluated on a subset of samples (due to the laborious nature of dietary fiber analysis). Because we desired to examine the functionality of bran independently of endosperm properties, bran samples were combined with a single based flour to make reconstituted whole grain flours for mixing and baking tests.
Specifically, the coarse particle size brans had significantly higher WRC and lower antioxidant activity. Other chemical components were not significantly impacted by particle size of the bran.
The differences in WRC among bran particle size fractions may be explained by the enhanced ability of coarse particles to trap weakly bound water compared with fine particles

Wheat Bran: overwiew part I

by luciano

Research regarding the composition and characteristics of wheat bran

1 – Wheat Bran
“Wheat bran includes the outer layers of the grain including the pericarp, head and aleurone layer (millers definition). Bran is an important by-product of milling wheat, when white flour is produced (see Section 3.3). The chemical composition (Table 5.4) is characterized by the high content (ò45%) of non-starch polysaccharides (food fibre) consisting mainly of arabinoxylans (ò60%) and cellulose (ò30%). Further characteristics are the relatively high content of minerals (potassium and phosphorus), unsaturated fatty acids (linoleic and oleic acids) and vitamins (nicotinamide, pantothenic acid and a-tocopherol). A disadvantage of bran is that the high lipid content can cause rancidity. Therefore bran is often heat treated (stabilized) to prevent enzymatic oxidation of fat.

Table 5.4. Chemical composition of wheat bran [18]

Due to the valuable nutritional composition, wheat bran has been widely used as component for animal feed (see Section 4.6), in particular for livestock like horses, cattle, goats, pigs, and rabbits. In recent years, wheat bran has increasingly been in the limelight as dietary supplement for human nutrition. Many studies have shown that the consumption of wheat bran, containing a unique mixture of valuable bioactive components, improves bowel functions and reduces the risk of colon cancer, type 2 diabetes, and cardiovascular diseases (see Section 6.4). Due to valuable antioxidants, its intake can prevent the onset of various oxidative stress-related diseases. Wheat bran is therefore frequently used as food additive, for example for bread, other baked products, and breakfast cereals [19]. It has been introduced into various further market segments including functional foods, nutraceuticals, and pharmaceuticals. Increased consumer awareness of the health benefits of bran induced great demand and food-grade bran can now easily be purchased in drugstores, health food shops, and supermarkets. Taken together, wheat bran is no longer a useless waste product but can be used in many areas of applications. Wheat-based raw materials Herbert Wieser, Katharina A. Scherf, in Wheat – An Exceptional Crop, 2020.”

2 – Wheat Bran
“Wheat bran is a by-product of wheat grain milling and grinding. The physiological effects of wheat bran can be split into the following: nutritional effects from its constituent nutrients; mechanical effects in the gastrointestinal tract due to its fiber content; and antioxidant effects arising from its phytochemical constituents. Wheat bran has higher antioxidant activity than other milled fractions, and contains various components such as phytic acid, polyphenols (including lignans and phenolic acids), vitamins, and minerals. These components of wheat bran possess health benefits for humans, including preventative effects against cancer and type 2 diabetes. Various studies have reported that these compounds exhibit significant antioxidant capabilities, including scavenging free radicals, chelating metal ions, and activating antioxidant enzymes, suggesting antioxidant properties of wheat bran. This chapter includes an overview of stress and oxidative stress and a discussion of the antioxidant properties of wheat bran. Chapter 15 – Antioxidant Properties of Wheat Bran against Oxidative Stress. Masashi Higuchi. https://doi.org/10.1016/B978-0-12-401716-0.00015-5.”

4 – Wheat bran
“Antioxidants (in bran) can interact with gluten proteins by reducing disulfide-sulfhydryl interchange reactions, thus impacting gluten protein aggregation. (Huang et al., 2018).”

5 – Wheat bran
“Bran is the most prominent co-product of the wheat milling process. In this process, the largest part of the endosperm tissue, i.e. the flour, is separated from the germ and bran after consecutive grinding, sieving and purification steps (Hemdane et al., 2016). From a botanical point of view, bran is a collection of multiple histological layers (i.e. outer and inner pericarp, seed coat and nucellar epidermis) of the outer part of the wheat kernel. However, wheat bran obtained as a milling fraction (referred as miller’s bran) also includes the aleurone layer and some residual endosperm tissue attached to it. Its yield varies between 13 to 19% of the total kernel weight (Deroover et al., 2020; Hemdane et al., 2016; Onipe et al., 2015). In this review, the term wheat bran refers to the miller’s bran.
Wheat bran mainly consists of arabinoxylan (17-33%), cellulose (9-14%) and fl-D-glucan (1-3%), but also starch (6-30%), proteins (14-26%), lipids (3-4%), lignin (3-10%), minerals (5-7%), phytic acid (4.5-5.5%), fructans (3-4%), and phenolic compounds (0.4-0.8%) (Hemdane et al., 2016). The pericarp is the main source of the kernel’s dietary fiber (mainly cross-linked arabinoxylans, cellulose and lignin). The aleurone layer is rich in arabinoxylan but also in lignan, phytic acid, minerals and vitamins (Deroover et al., 2020; Onipe et al., 2015).
Wheat minerals which are important for human health include iron, zinc, calcium, manganese, magnesium and copper. They are mainly located in the aleurone cells. Magnesium plays an important role in blood glucose homeostasis and insulin sensitivity (Veronese et al., 2016). However, minerals in wheat have low bioavailability because they are chelated by mainly phytic acid and/or because they are physically entrapped into rigid aleurone cells (Lemmens et al., 2019).
Bran is the main source of the phenolic compounds in wheat. Ferulic acid is the most abundant C6 – C3 phenolic acid. It is esterified to some of the arabinoses in the arabinoxylan chains. Arabinoxylan chains are cross-linked by formation of ferulic acid dimers and higher oligomers which are esterified to the arabinoxylan chains. Bran also contains the C6 – C3 phenolic acids sinapic and p-coumaric acid and the C6 – C1 phenolic acids p-hydroxybenzoic, vanillic, syringic, and gallic acid (Laddomada et al., 2015). Components of wheat and their modifications for modulating starch digestion: Evidence from in vitro and in vivo studies. Konstantinos Korompokis, Jan A. Delcour, in Journal of Cereal Science, 2023.”

5 – Wheat bran

“Wheat bran is a rich source of dietary fiber and other healthy components, which are biologically active, such as alkylresorcinol, ferulic acid, fl-glucan, arabinoxylan, lignans, and sterols (Pr¸ckler et al., 2014). Besides nonstarch carbohydrates (arabinoxylan, cellulose, fructan, and mixed-linkage fl-glucan), wheat bran contains starch, protein, lipids, and significant quantities of B vitamins and minerals (Hemdane et al., 2016a). The composition of wheat bran is presented in Table10.1 (USDA, 2015).”

6 – Wheat bran

“Wheat bran is a by-product of flour milling and frequently used as ingredient in diets for pigs (Huang et al., 1999; Hassan et al., 2008). It is composed of the pericarp and the outermost tissues of the seed, including the aleurone layer with variable amounts of remaining starchy endosperm (Jondreville et al., 2000; Hassan et al., 2008). Wheat bran constitutes almost 10% of the total weight of wheat milled for flour (Hassan et al., 2008). It is characterized by a high level of insoluble lignified fiber which is known to be extremely resistant to degradation in the gastrointestinal tract (Noblet and Le Goff, 2001). Molist et al. (2011) concluded that incorporation of WB in diets for piglets improved gut health by beneficially modulating the activity and composition of the intestinal microbiota.”

7 – Wheat bran
“Wheat bran is a by-product of the milling process of wheat. It usually contains 14-19% of total grain weight. As a rich source of dietary fibre, wheat bran contains 46% of non-starch polysaccharides, including arabinoxylan (70%), cellulose (24%) and beta-glucan (6%), and it also contains minor amounts of glucoglucomannan and arabinogalactan (Carre and Brillouet, 1986; Bertrand et al., 1981).
Depending on composition and particle size, wheat bran fractions may have negative effects on product quality, such as textural properties and loaf volume for bread. Reducing the particle size of wheat bran can influence product quality by increasing interaction surface and releasing reactive intracellular components (Noort et al., 2010).”