Grain processing and nutrition

Underrated aspects of a true Mediterranean diet: understanding traditional features for worldwide application of a "Planeterranean" diet

Over the last decades, the Mediterranean diet gained enormous scientific, social, and commercial attention due to proven positive effects on health and undeniable taste that facilitated a widespread popularity. Researchers have investigated the role of Mediterranean-type dietary patterns on human health all around the world, reporting consistent findings concerning its benefits. However, what does truly define the Mediterranean diet? The myriad of dietary scores synthesizes the nutritional content of a Mediterranean-type diet, but a variety of aspects are generally unexplored when studying the adherence to this dietary pattern. Among dietary factors, the main characteristics of the Mediterranean diet, such as consumption of fruit and vegetables, olive oil, and cereals should be accompanied by other underrated features, such as the following: (i) specific reference to whole-grain consumption; (ii) considering the consumption of legumes, nuts, seeds, herbs and spices often untested when exploring the adherence to the Mediterranean diet; (iii) consumption of eggs and dairy products as common foods consumed in the Mediterranean region (irrespectively of the modern demonization of dietary fat intake). Another main feature of the Mediterranean diet includes (red) wine consumption, but more general patterns of alcohol intake are generally unmeasured, lacking specificity concerning the drinking occasion and intensity (i.e., alcohol drinking during meals). Among other underrated aspects, cooking methods are rather simple and yet extremely varied. Several underrated aspects are related to the quality of food consumed when the Mediterranean diet was first investigated: foods are locally produced, minimally processed, and preserved with more natural methods (i.e., fermentation), strongly connected with the territory with limited and controlled impact on the environment. Dietary habits are also associated with lifestyle behaviors, such as sleeping patterns, and social and cultural values, favoring commensality and frugality. In conclusion, it is rather reductive to consider the Mediterranean diet as just a pattern of food groups to be consumed decontextualized from the social and geographical background of Mediterranean culture. While the methodologies to study the Mediterranean diet have demonstrated to be useful up to date, a more holistic approach should be considered in future studies by considering the aforementioned underrated features and values to be potentially applied globally through the concept of a "Planeterranean" diet.

Mineral, Nutritional, and Phytochemical Composition and Baking Properties of Teff and Watermelon Seed Flours

Demonstrated limitations in the mineral and nutritional composition of refined flours have led to calls for the possibility of enriching them with health-promoting supplements, such as high-value non-cereal seeds. Teff and watermelon seeds have been found suitable for the production of gluten-free flour, but so far, their potential to enrich conventional baking flours has not been comprehensively studied. Hence, the present study aimed at farinographic evaluation of dough based on refined wheat flour with additions of whole white teff (TF) and watermelon seed (WSF) and pomace (DWSF) flours (tested levels 10%, 20%, and 30%), as well as possibly extensive chemical characterization of the plant material tested, including LC-MS/MS, GC-MS, total phenolics, flavonoids, melatonin, and antioxidant potential. Most of the rheological traits were improved in the flour mixtures compared to the base white flour: development time and quality number (above 1.6-fold increase), softening and stability time (up to 1.3-fold change), and water absorption (up to 6%). Overall, the best results were achieved after the addition of watermelon seed pomace. The DWSF material was characterized by the highest levels of P, Mg, Na (7.5, 1.7, 0.4 g/kg, respectively), and Fe and Zn (124 and 27 mg/kg), while TF was the richest in Ca (0.9 g/kg) and Mn (43 mg/kg). Protein and fat levels were significantly higher in watermelon seeds compared to teff (about double and up to 10-fold, respectively). Phytochemical analyses highlighted the abundance of phenolics, especially flavones, in TF, WSF and DWSF flours (244, 93, and 721 mg/kg, respectively). However, the value of total polyphenols was low in all materials (<2 mg GAE/g), which also correlates with the low antioxidant potential of the samples. Watermelon seed pomace was characterized by significantly higher melatonin concentration (60 µg/kg) than teff (3.5 µg/kg). This study provides new information on the chemical composition and application opportunities of teff and watermelon seeds.

Variety and Quantity of Dietary-Insoluble Fiber Intake From Different Sources and Risk of New-Onset Diabetes

CONTEXT

The relationship between the variety and quantity of different sources of dietary-insoluble fiber intake and diabetes remain uncertain.

OBJECTIVE

We aimed to investigate the associations between the variety and quantity of insoluble fiber intake from 6 major food sources and new-onset diabetes, using data from the China Health and Nutrition Survey (CHNS).

METHODS

A total of 16 272 participants without diabetes at baseline from CHNS were included. Dietary intake was measured by 3 consecutive 24-hour dietary recalls combined with a household food inventory. Energy-adjusted dietary intake was used in analyses. The variety score of insoluble-fiber sources was defined as the number of specific-sourced insoluble fiber consumed at the appropriate level, accounting for both types and quantity of insoluble fiber. Participants with self-reported physician-diagnosed diabetes, or fasting glucose greater than or equal to 7.0 mmol/L or glycated hemoglobin A1c greater than or equal to 6.5% during follow-up were defined as having new-onset diabetes.

RESULTS

During a median follow-up of 9.0 years, 1101 participants developed new-onset diabetes. There were U-shaped associations for energy-adjusted dietary intake of total insoluble fiber, and energy-adjusted insoluble fiber derived from refined and whole grains; and L-shaped associations for energy-adjusted insoluble fiber derived from vegetables, legumes, fruits, and tubers with new-onset diabetes (all P for nonlinearity < .001). Moreover, a higher variety score of insoluble fiber sources was significantly associated with a lower risk of new-onset diabetes (per 1-score increment, hazard ratio, 0.61; 95% CI, 0.58-0.65).

CONCLUSION

There was an inverse association between the variety of insoluble fiber with appropriate quantity from different food sources and new-onset diabetes.

Temporal and Spatial Patterns of Zinc and Iron Accumulation during Barley (Hordeum vulgare L.) Grain Development

Breeding and engineering of biofortified crops will benefit from a better understanding of bottlenecks controlling micronutrient loading within the seeds. However, few studies have addressed the changes in micronutrient concentrations, localization, and speciation occurring over time. Therefore, we studied spatial patterns of zinc and iron accumulation during grain development in two barley lines with contrasting grain zinc concentrations. Microparticle-induced-X-ray emission and laser ablation-inductively coupled plasma mass spectrometry were used to determine tissue-specific accumulation of zinc, iron, phosphorus, and sulfur. Differences in zinc accumulation between the lines were most evident in the endosperm and aleurone. A gradual decrease in zinc concentrations from the aleurone to the underlying endosperm was observed, while iron and phosphorus concentrations decreased sharply. Iron co-localized with phosphorus in the aleurone, whereas zinc co-localized with sulfur in the sub-aleurone. We hypothesize that differences in grain zinc are largely explained by the endosperm storage capacity. Engineering attempts should be targeted accordingly.

Processing in the food chain: do cereals have to be processed to add value to the human diet?

Cereals and cereal products have a long history of use by humans. Recently, there have been some discussions regarding level of processing as a descriptor to define food products, including cereal-based foods. This has led to a somewhat emotional debate on food processing. Given the widespread inclusion of cereals in the diet, this review highlights the history of cereal processing as well as their consumption by humans. It provides an evidence-based discussion on their production, contribution to human nutrition, benefits and disadvantages. The present review illustrates the impact of processing on nutrients, as well as non-nutrients specifically in bread and ready-to-eat breakfast cereals (RTEC), two cereal-based foods which are widely consumed and integral parts of food-based dietary guidelines globally. As a category, most cereals must be processed in some way to enable consumption by humans as we are not equipped to survive exclusively on raw grains. Even thousands of years ago, the processing of cereals was a common practice by humans, turning raw grains into palatable, safe and nutritious foods. Modern processes for cereal-based products are efficient in providing safe and good-quality products to satisfy population needs, as well as helping to meet consumer expectations by providing a range of foods that allows for a varied and balanced diet. Today, RTEC and bread make significant contributions to dietary energy and nutrient requirements and underpin food-based dietary guidance globally. They have been positively linked with intake of dietary fibre, vitamins and minerals, especially when consumed as whole grain.

The Association between Whole Grain Products Consumption and Successful Aging: A Combined Analysis of MEDIS and ATTICA Epidemiological Studies

The quality of carbohydrates in the diet, including whole grains, matters greatly to health. There is emerging evidence supporting various protective effects from whole grain consumption against certain chronic diseases. However, being free of disease is not a requirement for healthy ageing, as many older adults have one or more health conditions but, when well controlled, have little influence on their wellbeing. The present study aimed to evaluate the association between whole grain consumption on successful aging, through an analysis of a sample of n = 3349, over-50-years-old men and women participating in the ATTICA and MEDIS population-based cross-sectional studies. Successful aging was evaluated using the validated successful aging index (SAI, range 0–10) comprising of health-related social, lifestyle and clinical components. High whole grain intake was positively associated with SAI as compared with low (b ± SE: 0.278 ± 0.091, p = 0.002), whereas no significant associations were observed between moderate whole grain consumption and SAI (p > 0.05). Increased whole grain intake has been associated with several health benefits, and, as is shown here, with higher successful aging levels. Therefore, consumption of whole grains should be encouraged, especially by replacing refined grains, without increasing total energy intake.

Cereal by-products as an important functional ingredient: effect of processing

Cereal is a staple food and major nutrition source throughout the world. The cereal bran obtained from milling as by-product contains multiple benefits and health-promoting components such as dietary fiber, minerals, vitamins, polyphenols, and phytosterols. However, these by-products are usually undervalued and used in animal feed. To increase the functional and food value, processing techniques linked to improving nutritional characteristics, sensory properties and reducing the inhibitory factors have been developed. These processing techniques include mechanical, enzymatic and thermal processing. It aims to improve the functional properties, enhance the extractability of beneficial food ingredients, reduce the complex structure of the bran and improve solubility, decrease the content of inhibitory factors and improve the bio-accessibility of micronutrients. This review highlights the various technological interventions and application of appropriate processing techniques to process cereal bran for the isolation of functional food ingredient and thus utilizing the nutritious by-product of cereal processing industry.

Development and charachterization of barley supllemented flavored chapattis

Food scientist are actively involved to improve the quality of wheat through composite flour technology by supplementing wheat flour with other grain flours. Barley grains are outstanding source of total dietary fibers (TDF) and offers remarkable quantity of active ingredients for health elevation and disease prevention. Purposely, the current research work was designed to improve the nutritional potential of wheat chapattis by including barley flour 10%, 20%, 30% along with the addition of functional blend (Methi powder and garlic paste) 2%, 4%, 6% levels respectively. Wheat and barley composite flour were analyzed for its chemical, mineral, antioxidant and total dietary composition. The supplementation of barley flour and functional blend into wheat flour enhanced the mineral. Addition of barley flour and functional blend increased total phenolic in composite flour 0.41 (control) to 0.69 mg GAE.100g-1 and DPPH from 20.95 - 23.82%. Total dietary fiber in composite flour varied form 3.11% (control) to 7.69% (30% barley flour with 6% functional blend). Total dietary fiber in chapattis ranged from 6.04 (control) to 8.21% (30% barley flour with 6% functional blend). 30% supplementation of barley flour and 4% addition of functional blend presented better sensory response of the prepared chapattis. All the outcomes revealed that nutritionally rich chapattis should be incorporated in daily diet to explore the dietary worth of barley.

Bioactive components and functional properties of biologically activated cereal grains: A bibliographic review

Whole grains provide energy, nutrients, fibers, and bioactive compounds that may synergistically contribute to their protective effects. A wide range of these compounds is affected by germination. While some compounds, such as β-glucans are degraded, others, like antioxidants and total phenolics are increased by means of biological activation of grains. The water and oil absorption capacity as well as emulsion and foaming capacity of biologically activated grains are also improved. Application of biological activation of grains is of emerging interest, which may significantly enhance the nutritional, functional, and bioactive content of grains, as well as improve palatability of grain foods in a natural way. Therefore, biological activation of cereals can be a way to produce food grains enriched with health-promoting compounds and enhanced functional attributes.

The integration of multi-platform MS-based metabolomics and multivariate analysis for the geographical origin discrimination of Oryza sativa L

For the authentication of white rice from different geographical origins, the selection of outstanding discrimination markers is essential. In this study, 80 commercial white rice samples were collected from local markets of Korea and China and discriminated by mass spectrometry-based untargeted metabolomics approaches. Additionally, the potential markers that belong to sugars & sugar alcohols, fatty acids, and phospholipids were examined using several multivariate analyses to measure their discrimination efficiencies. Unsupervised analyses, including principal component analysis and k-means clustering demonstrated the potential of the geographical classification of white rice between Korea and China by fatty acids and phospholipids. In addition, the accuracy, goodness-of-fit (R²), goodness-of-prediction (Q²), and permutation test p-value derived from phospholipid-based partial least squares-discriminant analysis were 1.000, 0.902, 0.870, and 0.001, respectively. Random Forests further consolidated the discrimination ability of phospholipids. Furthermore, an independent validation set containing 20 white rice samples also confirmed that phospholipids were the excellent discrimination markers for white rice between two countries. In conclusion, the proposed approach successfully highlighted phospholipids as the better discrimination markers than sugars & sugar alcohols and fatty acids in differentiating white rice between Korea and China.

Fecal excretion of Maillard reaction products and the gut microbiota composition of rats fed with bread crust or bread crumb

A comparison between the impacts of advanced (N^ε-carboxymethyllysine - CML) and terminal (melanoidins) Maillard reaction products from bread on gut microbiota was carried out in this study. Gut microbiota composition as well as fecal excretion of CML from both bread crust and bread crumb, and of melanoidins from bread crust were assessed on a rodent model. Rats were fed with pellets supplemented or not with 13% of bread crust, bread crumb, a fiber-free bread crust model (glucose, starch and gluten heated together) or a fiber-free-melanoidin-free bread model (glucose-starch and gluten heated separately) for four weeks. These model systems were developed to limit the presence of wheat-native dietary fibers such as cellulose, hemicelluloses and lignin. CML and melanoidins in pellets and feces were evaluated by LC/MS-MS and HPLC/fluorescence respectively, and gut microbiota composition was determined by cultivation and molecular approaches. Diets supplemented with crumb or the fiber-free-melanoidin-free model contained respectively 17% and 64% less melanoidins than their respective controls. A higher excretion of melanoidins was observed for rats fed with crust or bread crust model compared to their controls, confirming that melanoidins are in contact with gut microbiota. No impact of diets was observed on Firmicutes, Bacteroidetes and lactic flora. A decrease of enterobacteria was only observed for rats fed with the diet supplemented with the fiber-free bread crust model. Moreover, a significant increase of bifidobacteria numbers in the presence of crust, crumb and both bread models was observed, showing that this bifidogenic effect of bread is not due to the presence of melanoidins or wheat-native dietary fibers.

Mass spectrometry-based analysis of whole-grain phytochemicals

Whole grains are a rich source of several classes of phytochemicals, such as alkylresorcinols, benzoxazinoids, flavonoids, lignans, and phytosterols. A high intake of whole grains has been linked to a reduced risk of some major noncommunicable diseases, and it has been postulated that a complex mixture of phytochemicals works in synergy to generate beneficial health effects. Mass spectrometry, especially when coupled with liquid chromatography, is a widely used method for the analysis of phytochemicals owing to its high sensitivity and dynamic range. In this review, the current knowledge of the mass spectral properties of the most important classes of phytochemicals found in cereals of common wheat, barley, oats, and rye is discussed.

Ancient Wheat Diet Delays Diabetes Development in a Type 2 Diabetes Animal Model

AIM

The main objective was to investigate the physiological effects of ancient wheat whole grain flour diets on the development and progression of type 2 diabetes in Zucker diabetic fatty (ZDF) rats, and specifically to look at the acute glycemic responses.

METHODS

An intervention study was conducted, involving 40 ZDF rats consuming one of 5 different diets (emmer, einkorn, spelt, rye and refined wheat) for 9 weeks. Refined wheat flour and whole grain rye flour were included as negative and positive controls, respectively.

RESULTS

After 9 weeks of intervention, a downregulation of the hepatic genes PPAR-α, GLUT2, and SREBP-1c was observed in the emmer group compared to the control wheat group. Likewise, expression of hepatic SREBP-2 was lower for emmer, einkorn, and rye compared with the control group. Furthermore, spelt and rye induced a low acute glycemic response. The wheat group had higher HDL- and total cholesterol levels.

CONCLUSIONS

Ancient wheat diets caused a downregulation of key regulatory genes involved in glucose and fat metabolism, equivalent to a prevention or delay of diabetes development. Spelt and rye induced a low acute glycemic response compared to wheat.

The potential role of phytochemicals in wholegrain cereals for the prevention of type-2 diabetes

Diets high in wholegrains are associated with a 20-30% reduction in risk of developing type-2 diabetes (T2D), which is attributed to a variety of wholegrain components, notably dietary fibre, vitamins, minerals and phytochemicals. Most phytochemicals function as antioxidants in vitro and have the potential to mitigate oxidative stress and inflammation which are implicated in the pathogenesis of T2D. In this review we compare the content and bioavailability of phytochemicals in wheat, barley, rice, rye and oat varieties and critically evaluate the evidence for wholegrain cereals and cereal fractions increasing plasma phytochemical concentrations and reducing oxidative stress and inflammation in humans. Phytochemical content varies considerably within and among the major cereal varieties. Differences in genetics and agro-climatic conditions explain much of the variation. For a number of the major phytochemicals, such as phenolics and flavanoids, their content in grains may be high but because these compounds are tightly bound to the cell wall matrix, their bioavailability is often limited. Clinical trials show that postprandial plasma phenolic concentrations are increased after consumption of wholegrain wheat or wheat bran however the magnitude of the response is usually modest and transient. Whether this is sufficient to bolster antioxidant defences and translates into improved health outcomes is still uncertain. Increased phytochemical bioavailability may be achieved through bio-processing of grains but the improvements so far are small and have not yet led to changes in clinical or physiological markers associated with reduced risk of T2D. Furthermore, the effect of wholegrain cereals and cereal fractions on biomarkers of oxidative stress or strengthening antioxidant defence in healthy individuals is generally small or nonexistent, whereas biomarkers of systemic inflammation tend to be reduced in people consuming high intakes of wholegrains. Future dietary intervention studies seeking to establish a direct role of phytochemicals in mediating the metabolic health benefits of wholegrains, and their potential for mitigating disease progression, should consider using varieties that deliver the highest possible levels of bioavailable phytochemicals in the context of whole foods and diets. Both postprandial and prolonged responses in systemic phytochemical concentrations and markers of inflammation and oxidative stress should be assessed along with changes related to health outcomes in healthy individuals as well as those with metabolic disease.

Bioactive compounds in cereal grains – occurrence, structure, technological significance and nutritional benefits – a review

This review presents current information about principal, biologically active compounds contained in grains of cereals that are most popular in Europe (wheat, rye, barley and oat). The tendency to provide consumers with safe foods, which promote their health and are based on cereal grains and/or their components with the high nutritive value, has been recently observed. The intake of protective substances contained in whole grains and their fractions contributes to a decreased risk of food-dependent diseases like the coronary heart disease and insulin-dependent diabetes. This study describes the structure, occurrence in cereal grains, technological importance and beneficial influence on human health of bioactive substances such as arabinoxylans, β-glucans, alkylresorcinols, tocols and phytosterols.

Effect of storage and processing of Brazilian flaxseed on lipid and lignan contents

Flaxseed has been widely studied around the world; its incorporation into products habitually consumed by human populations has been stimulated due to its unique nutritional value. The objective of this study was to evaluate the chemical composition of Brazilian flaxseed, to analyze the stability of lipids present in whole flaxseed flour (WFF) or partially defatted flaxseed flour (DFF) stored under several temperatures, and to investigate the effect of bread making on a product containing flaxseed. Whole flaxseed flour presented (g.100 g-1) 25.7 of insoluble fiber, 10.7 of soluble fiber, 38.9 of lipids, and 2.65 of lignan. Defatted flaxseed flour presented 65% less lipids, 36% more fiber and 56% more lignan than whole flaxseed flour. The fatty acid profile was maintained in the defatted flaxseed flour, and it presented a stable composition during storage under ambient temperature, refrigeration, and freezing. The fatty acid profile was similar in the bread containing defatted flaxseed flour after dough development, baking, and storage at room temperature or refrigerated. After baking, 89% of the lignan content was kept in bread. Results show that Brazilian flaxseed has an interesting chemical composition, and that defatted flaxseed, by-product of lipid extraction, presents a good stability to grind and storage under several temperatures. Thus, defatted flaxseed flour can be incorporated in bread, increasing its nutritional and functional value.

Whole grain cereals: functional components and health benefits

Cereal-based food products have been the basis of the human diet since ancient times. Dietary guidelines all over the world are recommending the inclusion of whole grains because of the increasing evidence that whole grains and whole-grain-based products have the ability to enhance health beyond the simple provision of energy and nutrients. In this review we will examine the main chemical components present in whole grains that may have health enhancing properties (dietary fiber, inulin, beta-glucan, resistant starch, carotenoids, phenolics, tocotrienols, and tocopherols) and the role that whole grains may play in disease prevention (cardiovascular diseases and strokes, hypertension, metabolic syndrome, type 2 diabetes mellitus, obesity, as well as different forms of cancer). The knowledge derived from the functional properties of the different chemical components present in whole grains will aid in the formulation and development of new food products with health enhancing characteristics.

Effects of whole grains on coronary heart disease risk

Characterizing which types of carbohydrates, including whole grains, reduce the risk for coronary heart disease (CHD) is challenging. Whole grains are characterized as being high in resistant carbohydrates as compared with refined grains, meaning they typically are high in fiber, nutrients, and bound antioxidants. Whole grain intake consistently has been associated with improved cardiovascular disease outcomes, but also with healthy lifestyles, in large observational studies. Intervention studies that assess the effects of whole grains on biomarkers for CHD have mixed results. Due to the varying nutrient compositions of different whole grains, each could potentially affect CHD risk via different mechanisms. Whole grains high in viscous fiber (oats, barley) decrease serum low-density lipoprotein cholesterol and blood pressure and improve glucose and insulin responses. Grains high in insoluble fiber (wheat) moderately lower glucose and blood pressure but also have a prebiotic effect. Obesity is inversely related to whole grain intake, but intervention studies with whole grains have not produced weight loss. Visceral fat, however, may be affected favorably. Grain processing improves palatability and can have varying effects on nutrition (e.g., the process of milling and grinding flour increases glucose availability and decreases phytochemical content whereas thermal processing increases available antioxidants). Understanding how individual grains, in both natural and processed states, affect CHD risk can inform nutrition recommendations and policies and ultimately benefit public health.

Relation between estimates of cornstarch digestibility by the Englyst in vitro method and glycemic response, subjective appetite, and short-term food intake in young men

BACKGROUND

Starch composition and rate of digestion are determinants of blood glucose concentrations and food intake (FI).

OBJECTIVE

Our objective was to describe relations between estimates of digestibility of starches by the in vitro Englyst method and their effect on blood glucose concentrations, subjective appetite, and FI in young men.

DESIGN

Subjects consumed 5 soups containing 50 g maltodextrin, whole-grain, high-amylose, regular cornstarch, or no added starch at 1-wk intervals. Ad libitum FI was measured at 30 min (experiment 1) or 120 min (experiment 2) later, which were the estimated times of digestion of a rapidly digestible starch (RDS) and slowly digestible starch, respectively. Blood glucose concentrations and appetite were measured pre- and postmeal.

RESULTS

At 30 min, FI was reduced by maltodextrin only [86% RDS, 12% resistant starch (RS); P < 0.05], but at 120 min FI was reduced by whole-grain (24% RDS, 66% RS), high-amylose corn (40% RDS, 48% RS), and regular corn (27% RDS, 39% RS) (P < 0.0001). The premeal blood glucose concentration at 30 and 120 min was highest and lowest after maltodextrin treatment, respectively (P < 0.0001). After the meal, the blood glucose area under the curve at 30 min was lower after all starch treatments (P < 0.05), but at 120 min the blood glucose area under the curve was lower only after the regular cornstarch treatment (P < 0.05). Premeal appetite decreased by all treatments (P < 0.05).

CONCLUSION

The in vitro estimates of starch digestibility by the Englyst method predicted the effects of starch composition on blood glucose concentrations and FI in young men 30 and 120 min after consumption. This trial was registered at clinicaltrials.gov as NCT00980941 for experiment 1 and NCT00988689 for experiment 2.

Whole grains and human health

Epidemiological studies find that whole-grain intake is protective against cancer, CVD, diabetes, and obesity. Despite recommendations to consume three servings of whole grains daily, usual intake in Western countries is only about one serving/d. Whole grains are rich in nutrients and phytochemicals with known health benefits. Whole grains have high concentrations of dietary fibre, resistant starch, and oligosaccharides. Whole grains are rich in antioxidants including trace minerals and phenolic compounds and these compounds have been linked to disease prevention. Other protective compounds in whole grains include phytate, phyto-oestrogens such as lignan, plant stanols and sterols, and vitamins and minerals. Published whole-grain feeding studies report improvements in biomarkers with whole-grain consumption, such as weight loss, blood-lipid improvement, and antioxidant protection. Although it is difficult to separate the protective properties of whole grains from dietary fibre and other components, the disease protection seen from whole grains in prospective epidemiological studies far exceeds the protection from isolated nutrients and phytochemicals in whole grains.

Alkylresorcinols in selected Polish rye and wheat cereals and whole-grain cereal products

The alkylresorcinol content and homologue composition in selected Polish rye and wheat cultivars and selected whole-grain cereal products were determined in this study. Cereal grains and whole-grain cereal products were extracted with acetone, whereas bread types were extracted with hot 1-propanol. The average alkylresorcinol content in tested rye (approximately 1100 mg/kg DM) and wheat (approximately 800 mg/kg DM) grains harvested in Poland was within the range previously reported in Swedish and Finnish samples. The total alkylresorcinol content in tested cereal products available on the Polish market varied from very low levels in barley grain-based foods up to 3000 mg/kg DM in wheat bran. The total alkylresorcinol content in 14 bread samples extracted with hot 1-propanol varied from approximately 100 mg/kg DM in whole bread made with honey up to approximately 650 mg/kg DM in whole-rye bread. Calculated ratios of C17:0 to C21:0 homologues, a useful parameter previously used to distinguish between rye and wheat cereals and their derived products, was about 1.2-1.4 in rye products, about 0.2 in wheat products, and varied between 0.2 and 0.6 in cereal-derived products containing a mixture of whole rye and/or wheat. The data set obtained were subsequently compared using cluster and principal component analysis, which allowed the tested cereal products to be classified into two major groups consisting of whole-rye or whole-wheat products, respectively. On the basis of that approach, mixed cereal products containing rye and wheat bran or whole rye and wheat flour were grouped between those two well-defined clusters. Our work not only provides a detailed examination of alkylresorcinols in selected Polish rye and wheat cultivars and selected whole-grain cereal products, but also demonstrates that this type of analysis accompanied by the use of proper statistical algorithms offers an objective way to evaluate the quality of whole-grain rye and/or wheat and their derived products.

Ferulic acid from aleurone determines the antioxidant potency of wheat grain (Triticum aestivum L.)

Grain is an important source of phytochemicals, which have potent antioxidant capacity. They have been implicated in the beneficial health effect of whole grains in reducing cardiovascular disease and type 2 diabetes. The aim of the present study was to identify the most important antioxidant fractions of wheat grain. It was found that the aleurone content of these fractions was highly correlated with the antioxidant capacity of the fractions (r = 0.96, p < 0.0001). Ferulic acid appeared to be the major contributor to the antioxidant capacity in fractions with higher antioxidant capacity. The contribution of protein was rather limited. It was concluded that the antioxidant potency of wheat grain fractions is predominantly determined by aleurone content, which can be attributed to the presence of relatively large amounts of phenolic compounds, primarily ferulic acid.

Effect of baking process on postprandial metabolic consequences: randomized trials in normal and type 2 diabetic subjects

OBJECTIVE

To determine the impact of the form, fibre content, baking and processing on the glycaemic, insulinaemic and lipidaemic responses of different French breads.

DESIGN AND SUBJECTS

First study: Nine healthy subjects were randomized to consume in a crossover design one of six kinds of French bread (each containing 50 g available carbohydrate): classic baguette, traditional baguette, loaf of wholemeal bread (WM-B), loaf of bread fermented with yeast or with leaven, a sandwich and a glucose challenge as reference.

RESULTS

The glycaemic index (GI) values ranged from 57+/-9% (mean+/-s.e.m.), for the traditional baguette, to 85+/-27% for the WM-B. No significant difference was found among the different tested bread. The insulinaemic index (II), however, of the traditional baguette and of the bread fermented with leaven were lower than the other breads (analysis of variance: P<0.01). Postprandial plasma triglycerides showed similar profiles. The traditional baguette tended to decrease postprandial free fatty acids compared to levels after the classic baguette.

RESULTS

The GI of the traditional baguette was lower than that of the classic baguette (n=8, venous blood: 70+/-4 vs 75+/-4, P=0.002; capillary blood: 69+/-5 vs 83+/-6, P=0.028, respectively).

CONCLUSIONS

Some varieties of French bread (the TB) have lower II, in healthy subjects, and lower GI, in type 2 diabetic subjects, than that of the other varieties. These results might be due to bread processing difference rather than fibre content.

SPONSORSHIPS

Supported by grants from the National French Milling Association.

Alkylresorcinols as markers of whole grain wheat and rye in cereal products

The alkylresorcinol (AR) content of Swedish wheat grain samples, as well as of cereal ingredients and cereal foods containing wheat and rye, was determined. The average total AR content in Swedish wheat was 412 microg/g (ranging between 227 and 639 microg/g), which is lower than that in Swedish rye analyzed in a previous study. The relative composition of AR homologues was consistent for wheat samples and differed markedly from that of rye. Notably, the ratio of the homologues C17:0/C21:0 was approximately 0.1 in wheat and approximately 1.0 in rye, indicating that it can be used to distinguish between those two cereals. The AR content in cereal foods commonly consumed in Sweden varied widely, from nondetectable levels in white wheat flour and products not containing the outer parts of wheat and/or rye to >900 microg/g in some whole grain rye products. AR content in cereal foods was calculated from their recipes using average AR values for the cereal ingredients determined in this study. As there was a good correlation between calculated and analyzed AR levels in cereal foods (R2 = 0.91), it is possible to estimate the proportion of whole grain wheat and/or rye in a given cereal product on the basis of AR content and C17:0/C21:0 ratio. ARs appear to be good markers of whole grain wheat and rye in foods, and their analysis may be an objective way to identify foods rich in whole grain wheat and/or rye or brans thereof.

Dietary fiber and coronary disease: does the evidence support an association?

Large, prospective, epidemiologic studies show a protective effect of dietary fiber against coronary heart disease (CHD) and form the basis for new recommendations from the National Academy of Science for fiber intake (38 and 25 g/d for young men and women, respectively, based on an intake of 14 g of fiber per 1000 kcal). Mechanisms by which fibers may protect against CHD include lowering blood cholesterol (soluble fibers), attenuating blood triglyceride levels (mostly soluble fibers), decreasing hypertension (all fibers), and normalizing postprandial blood glucose levels (all fibers). An important consideration in making diet recommendations to protect against CHD is that the total amount of fiber from fiber-containing foods is important, and individuals should not just be counseled to focus on soluble fiber.

Absorption of dietary alkylresorcinols in ileal-cannulated pigs and rats

Alkylresorcinols (AR) are amphiphilic 1,3-dihydroxy-5-alkyl phenolic lipids. AR in food are only found in the outer layers of wheat and rye grains, and in whole grains are present at concentrations of 500-1000 microg/g. In wheat and rye, there are five main homologues, differing in the length of the odd-numbered alkyl chain (from seventeen to twenty-five C atoms long). Because AR may be bioactive, and might serve as biomarkers for these cereals, their absorption was investigated in model experiments with pigs and rats. Pigs with a cannula in the terminal ileum were fed four diets containing rye fractions with different levels of AR and the ileal effluents were analysed. The ileal recovery of AR was found to vary between 21 and 40 %, with no major difference between different chain-length homologues. The absorption of AR by rats was investigated by feeding (14)C-labelled heneicosylresorcinol (C21 : 0). Of the total activity, about 34 % was recovered in the urine, showing that the labelled AR was absorbed and metabolised by rats. AR were mostly cleared from rats by 60 h. It is concluded that AR are absorbed in the small intestine of single-stomached animals and excreted in metabolised form in the urine, and might contribute to the nutritional qualities of wholegrain wheat and rye diets.

Alkylresorcinols in cereals and cereal products

The alkylresorcinol (AR) content of 8 commonly consumed cereals, 125 Triticum cultivars, milling fractions of wheat and rye, bread, and other cereal products was analyzed. ARs were found in wheat (489-1429 microgram/g), rye (720-761 microgram/g), triticale (439-647 microgram/g), and barley (42-51 microgram/g), but not in rice, oats, maize, sorghum, or millet. One durum wheat variety was found to have an exceptionally low level of ARs (54 microgram/g) compared to other durum wheat varieties (589-751 microgram/g) and Triticumspecies analyzed. The AR content of milling fractions closely followed the ash content and could be used as a marker of the presence of bran in flour. Using hot 1-propanol extraction, all ARs could be extracted from bread, contrary to previous studies which suggested that ARs were destroyed during baking. Cereal products varied greatly in AR content, with those containing wheat bran or whole rye having the highest content.

Cereal alkylresorcinols are absorbed by humans

Currently there is no biomarker to link consumption of whole grain cereals and their observed health benefits. A candidate for a biomarker of whole grain wheat and rye intake is a class of phenolic lipids, the alkylresorcinols (AR). Studies to determine the uptake of AR in humans were carried out with a low fiber diet based on white wheat bread (AR free) and a high fiber diet based on rye bran-enriched bread (AR rich). For each diet, two meal frequencies were used: nibbling (7 small meals/d) and ordinary (3 large meals/d). Ten human ileostomy-operated subjects started with the AR-free diet for 2 wk, wk 1 on either nibbling or ordinary and wk 2 on the other meal frequency in a crossover design, followed by a 1-wk washout period, before the AR-rich diet performed as the AR-free diet. Food and ileostomy samples were analyzed for AR. Approximately 40% of AR were recovered in effluent from the small intestine, indicating that 60% of AR are taken up from or converted in the small intestine (ileal digestibility) with no difference between nibbling and ordinary meal frequencies. AR absorbed by humans may be of importance as bioactive compounds, or as a biomarker of whole grain wheat and rye intake.