Microbial and endogenous metabolic conversions of rye phytochemicals

Impact of nanotechnology on the oral delivery of phyto-bioactive compounds

Nanotechnology is an advanced field that has remarkable nutraceutical and food applications. Phyto-bioactive compounds (PBCs) play critical roles in promoting health and disease treatment. However, PBCs generally encounter several limitations that delay their widespread application. For example, most PBCs have low aqueous solubility, poor biostability, poor bioavailability, and a lack of target specificity. Moreover, the high concentrations of effective PBC doses also limit their application. As a result, encapsulating PBCs into an appropriate nanocarrier may increase their solubility and biostability and protect them from premature degradation. Moreover, nanoencapsulation could improve absorption and prolong circulation with a high opportunity for targeted delivery that may decrease unwanted toxicity. This review addresses the main parameters, variables, and barriers that control and affect oral PBC delivery. Moreover, this review discusses the potential role of biocompatible and biodegradable nanocarriers in improving the water solubility, chemical stability, bioavailability, and specificity/selectivity of PBCs.

Clover Root Uptake of Cereal Benzoxazinoids (BXs) Caused Accumulation of BXs and BX Transformation Products Concurrently with Substantial Increments in Clover Flavonoids and Abscisic Acid

Metabolomic studies on root uptake and transformation of bioactive compounds, like cereal benzoxazinoids (BXs) in non-BX producing plants, are very limited. Therefore, a targeted mass-spectrometry-based metabolomics study was performed to elucidate the root uptake of BXs in white clover (Trifolium repens L.) and the impact of absorbed BXs on intrinsic clover secondary metabolites. Clover plants grew in a medium containing 100 μM of individual BXs (five aglycone and one glycoside BXs) for 3 weeks. Subsequently, plant tissues were analyzed by liquid chromatography-tandem mass spectrometry to quantify the BXs and clover secondary metabolite concentrations. All BXs were taken up by clover roots and translocated to the shoots. Upon uptake of 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), 2-hydroxy-1,4-benzoxazin-3-one (HBOA), and 2-β-d-glucopyranosyloxy-1,4-benzoxazin-3-one (HBOA-glc), the parent compounds and a range of transformation products were seen in the roots and shoots. The individual BX concentrations ranged from not detected (nd) to 469 μg/g of dry weight (dw) and from nd to 170 μg/g of dw in the roots and shoots, respectively. The root uptake of BXs altered the composition of intrinsic clover secondary metabolites. In particular, the concentration of flavonoids and the hormone abscisic acid increased substantially in comparison to control plants.

Effect of Replacing Maize Grain by Hybrid Rye Grain in the TMR on Performance of Mid-Lactating Dairy Cows

Grain from traditional varieties of rye is not commonly used in dairy cattle nutrition. However, new hybrid varieties of rye currently available are characterized by some nutritional and agrotechnical benefits. This paper deals with the hypothesis that rye grain derived from a hybrid variety may be an alternative for maize grain in diets for dairy cattle. Sixteen lactating Polish Holstein- Friesian cows were divided into two groups according to their parity (8 primi- and 8 multiparous), stage of lactation (106 ± 30 days after calving) and milk yield (34 ± 4 kg/day). Cows were fed a total mixed ration (TMR) containing grass silage and whole crop maize silage and 29.2% of the concentrate (in dry matter). The latter contained approximately 48% (as fed) of either maize grain (M) or hybrid rye grain (HR) as a main source of cereal grain. Experimental diets were fed for 9 weeks. The use of HR as a substitute for M did not affect (P>0.05) dry matter intake and milk yield. There were no differences between treatments in the content of milk solids, amino acids, and fatty acid profile. However, substituting M by HR positively influenced composition of milk protein fractions by increasing the proportion of α-casein (37.0 vs 39.7%; P<0.01) and к-casein (6.5 vs 7.3%; P=0.02) as well as decreasing the proportion of β-casein (28.8 vs 27.8%; P=0.02) and sensory characteristics of the milk (body and texture, and taste; P<0.05). In turn, the composition of the diet did not affect the technological suitability for processing of milk fat (acid and peroxide number, melting and solidification temperature), rennet coagulation time, heat stability or titratable acidity. This study has shown that hybrid rye grain may be an alternative for maize grain in a TMR based on grass and whole maize silage for mid-lactation dairy cows. Further studies are needed with higher proportion of hybrid rye grain in TMR or with other roughages used in a basal diet to fully determine efficiency of hybrid rye grain use in diets for dairy cows.

Rye Flour and Rye Bran: New Perspectives for Use

Rye (Secale cereale L.) is abundantly cultivated in countries like Europe and North America, particularly in regions where soil and climate conditions are unfavorable for the growth of other cereals. Among all the cereals generally consumed by human beings, rye grains are characterized by the presence of the highest content of fiber. They are also a rich source of many phytochemical compounds, which are mainly distributed in the outer parts of the grain. This review focuses on the current knowledge regarding the characteristics of rye bran and wholemeal rye flour, as well as their applications in the production of both food and nonfood products. Previous studies have shown that the physicochemical properties of ground rye products are determined by the type of milling technique used to grind the grains. In addition, the essential biologically active compounds found in rye grains were isolated and characterized. Subsequently, the possibility of incorporating wholemeal rye flour, rye bran, and other compounds extracted from rye bran into different industrial products is discussed.

Rye: A wonder crop with industrially important macromolecules and health benefits

Rye (Secale cereale) is a rich source of macromolecules, especially starch, fiber, and proteins which encourages the researchers and industries to use it for various purposes including bakery products, beverages and edible films formulation. However, despite many nutritional and health benefiting properties, rye has not been explored up to its full potential. Interest of consumers in formulating foods with high fiber and phenolic compounds has generated our interest in compiling the detailed information on rye. The present review on rye grains summarizes the existing scientific data on rye macronutrients (starch, arabinoxylan, β-glucan, fructan and proteins) and their corresponding industrial importance. Detailed description in this review unfolds the potential of rye grains for human nutrition. This review provides comprehensive knowledge and fills the remaining gap between the previous and latest scientific findings. Comprehensive information on rye nutrients along with health benefits will help to open a new era for scientific world and industrial sectors.

Grains - a major source of sustainable protein for health

Cereal grains are the main dietary source of energy, carbohydrates, and plant proteins world-wide. Currently, only 41% of grains are used for human consumption, and up to 35% are used for animal feed. Cereals have been overlooked as a source of environmentally sustainable and healthy plant proteins and could play a major role in transitioning towards a more sustainable food system for healthy diets. Cereal plant proteins are of good nutritional quality, but lysine is often the limiting amino acid. When consumed as whole grains, cereals provide health-protecting components such as dietary fiber and phytochemicals. Shifting grain use from feed to traditional foods and conceptually new foods and ingredients could improve protein security and alleviate climate change. Rapid development of new grain-based food ingredients and use of grains in new food contexts, such as dairy replacements and meat analogues, could accelerate the transition. This review discusses recent developments and outlines future perspectives for cereal grain use.

Changes in extractable phenolic profile during natural fermentation of wheat, sorghum and teff

Whole grain polyphenols are associated with structure-specific bioactive properties. However, the phenolic profile of grain ingredients can be significantly altered by processes like fermentation. This study investigated how polyphenol profiles in different cereal grains respond to microbial metabolism during sourdough fermentation. Whole grain wheat (white and red), sorghum (white and lemon-yellow), and teff (white and brown) flours were subjected to natural sourdough fermentation for 48-96 h, and phenolic profiles and their metabolites monitored using UPLC-tandem quadrupole MS. Flavonoid O-glycosides (dominant in sorghum) were rapidly metabolized (66% reduction in 48 h) to release aglycones (2.5 fold increase). O-Glycoside groups in mixed O/C-glycosides (dominant in teff) were selectively hydrolyzed, but more slowly (11-32% reduction in 48 h) than homo-O-glycosides, suggesting steric hindrance from the C-glycoside groups. Flavonoid C-glycosides (dominant in wheat) and aglycones (white sorghum) were generally stable to microbial degradation. Extractable phenolic acids and their esters (most abundant in white sorghum) were extensively degraded (80% reduction in 48 h) with few metabolites detected at the end of fermentation. Thus, extractable phenolics in sorghum were generally most extensively metabolized, whereas those in wheat were the least impacted by sourdough fermentation. New microbial metabolites, putatively identified as O-methylcatechol-vinyl-isoflavans, were detected in all fermented samples, with levels increasing with fermentation time. Based on structure, these compounds were likely derived from cell wall C-C linked diferulic acid metabolism. As expected, Folin reactive phenols and antioxidant capacity increased in fermented samples, but the extent was distinctly smaller in sorghums (1.3-1.9 fold) vs teff (2.4-3.2 fold) and wheat (2.0-6.1 fold), likely due to higher presence of easily metabolizable phenolics in sorghum. The phenolic profile of a cereal grain affects the products of microbial metabolism during fermentation, and may thus alter phenolic-dependent bioactive properties associated with a specific grain.

Comprehensive Two-Dimensional Gas Chromatography-Mass Spectrometry Analysis of Exhaled Breath Compounds after Whole Grain Diets

Exhaled breath is a potential noninvasive matrix to give new information about metabolic effects of diets. In this pilot study, non-targeted analysis of exhaled breath volatile organic compounds (VOCs) was made by comprehensive two-dimensional gas chromatography-mass spectrometry (GCxGC-MS) to explore compounds relating to whole grain (WG) diets. Nine healthy subjects participated in the dietary intervention with parallel crossover design, consisting of two high-fiber diets containing whole grain rye bread (WGR) or whole grain wheat bread (WGW) and 1-week control diets with refined wheat bread (WW) before both diet periods. Large interindividual differences were detected in the VOC composition. About 260 VOCs were detected from exhaled breath samples, in which 40 of the compounds were present in more than half of the samples. Various derivatives of benzoic acid and phenolic compounds, as well as some furanones existed in exhaled breath samples only after the WG diets, making them interesting compounds to study further.

"notame": Workflow for Non-Targeted LC-MS Metabolic Profiling

Metabolomics analysis generates vast arrays of data, necessitating comprehensive workflows involving expertise in analytics, biochemistry and bioinformatics in order to provide coherent and high-quality data that enable discovery of robust and biologically significant metabolic findings. In this protocol article, we introduce notame, an analytical workflow for non-targeted metabolic profiling approaches, utilizing liquid chromatography-mass spectrometry analysis. We provide an overview of lab protocols and statistical methods that we commonly practice for the analysis of nutritional metabolomics data. The paper is divided into three main sections: the first and second sections introducing the background and the study designs available for metabolomics research and the third section describing in detail the steps of the main methods and protocols used to produce, preprocess and statistically analyze metabolomics data and, finally, to identify and interpret the compounds that have emerged as interesting.

Factors affecting intake, metabolism and health benefits of phenolic acids: do we understand individual variability?

Introduction

Phenolic acids are important phenolic compounds widespread in foods, contributing to nutritional and organoleptic properties.

Factors affceting individual variability

The bioavailability of these compounds depends on their free or conjugated presence in food matrices, which is also affected by food processing. Phenolic acids undergo metabolism by the host and residing intestinal microbiota, which causes conjugations and structural modifications of the compounds. Human responses, metabolite profiles and health responses of phenolics, show considerable individual variation, which is affected by absorption, metabolism and genetic variations of subjects.

Opinion

A better understanding of the gut-host interplay and microbiome biochemistry is becoming highly relevant in understanding the impact of diet and its constituents. It is common to study metabolism and health benefits separately, with some exceptions; however, it should be preferred that health responders and non-responders are studied in combination with explanatory metabolite profiles and gene variants. This approach could turn interindividual variation from a problem in human research to an asset for research on personalized nutrition.

Recommendations for characterization and reporting of dietary fibers in nutrition research

Dietary fiber (DF) comprises a wide range of naturally occurring and modified materials with substantial variations in physical and chemical properties and potential physiologic effects. Although nutrition studies testing the effects of DF usually provide extensive detail on the physiologic responses, many still fail to adequately report the type and properties of the DF itself. This weakens the ability to directly replicate and compare studies and to establish structure-function relations. We outline the factors that affect DF functionality and provide 4 overarching recommendations for the characterization and reporting of DF preparations and DF-containing foods in nutrition research. These relate to 1) undertaking characterization methods that reflect the study hypothesis; 2) adequate reporting of DF source, quantity, and composition; 3) measurement of DF rheological properties; and 4) estimation of the DF fermentation rate and extent. Importantly, the food matrix of the test products should also be considered, because this can influence DF functionality and hence the apparent DF efficacy for health-relevant outcomes. Finally, we point out differences in DF functionality to be considered in acute and longer-term trials, the need to design the control treatment according to the research question, and the importance of reporting the amount and type of DF in the background diet.

Metabolic profiling of sourdough fermented wheat and rye bread

Sourdough fermentation by lactic acid bacteria is commonly used in bread baking, affecting several attributes of the final product. We analyzed whole-grain wheat and rye breads and doughs prepared with baker’s yeast or a sourdough starter including Candida milleri, Lactobacillus brevis and Lactobacillus plantarum using non-targeted metabolic profiling utilizing LC–QTOF–MS. The aim was to determine the fermentation-induced changes in metabolites potentially contributing to the health-promoting properties of whole-grain wheat and rye. Overall, we identified 118 compounds with significantly increased levels in sourdough, including branched-chain amino acids (BCAAs) and their metabolites, small peptides with high proportion of BCAAs, microbial metabolites of phenolic acids and several other potentially bioactive compounds. We also identified 69 compounds with significantly decreased levels, including phenolic acid precursors, nucleosides, and nucleobases. Intensive sourdough fermentation had a higher impact on the metabolite profile of whole-grain rye compared to milder whole-grain wheat sourdough fermentation. We hypothesize that the increased amount of BCAAs and potentially bioactive small peptides may contribute to the insulin response of rye bread, and in more general, the overall protective effect against T2DM and CVD.

Diet-derived changes by sourdough-fermented rye bread in exhaled breath aspiration ion mobility spectrometry profiles in individuals with mild gastrointestinal symptoms

The potential of utilising exhaled breath volatile organic compound (VOC) profiles in studying diet-derived metabolic changes was examined. After a four-week initial diet period with white wheat bread (WW), seven participants received in randomised order high-fibre diets containing sourdough whole grain rye bread (WGR) or white wheat bread enriched with bioprocessed rye bran (WW + BRB), both for 4 weeks. Alveolar exhaled breath samples were analysed with ChemPro^®100i analyser (Environics OY, Mikkeli, Finland) at the end of each diet period in fasting state and after a standardised meal. The AIMS signal intensities in fasting state were different after the WGR diet as compared to other diets. The result suggests that WGR has metabolic effects not completely explained by the rye fibre content of the diet. This study encourages to utilise the exhaled breath VOC profile analysis as an early screening tool in studying physiological functionality of foods.