Peter R Ellis

• Biochemistry
• Head of Biopolymers Group at King's College London

Anaerobic digestion (AD) offers a sustainable biotechnology to recover resources from carbon-rich wastewater, such as food-processing wastewater. Despite crude wastewater characterisation, the impact of detailed chemical fingerprinting on AD remains underexplored. This study investigated the influence of fermentation-wastewater composition and oper...

Anaerobic digestion (AD) offers a sustainable biotechnology to recover resources from carbon- and nutrient-rich wastewater streams, such as food-processing wastewater. Despite the wide adoption of crude wastewater characterisation, the impact of detailed chemical fingerprinting on AD remains underexplored. This study investigated the influence of f...

Food waste represents a growing global crisis equivalent to ∼1.3 billion tonnes/year. This review provides an overview of the potential of food waste as a carbon source for microbial upcycling using anaerobic digestion (AD) for bioenergy coupled with single-cell protein (SCP) production. We estimate biogas potential from food waste to be sufficient...

(Poly)phenol (PP)-rich blackcurrant (BC) extracts reduce postprandial glucose concentrations. Combinations with other fruit (poly)phenols and fruit fibre may enhance the effect. This study investigated the acute effects of combinations of BC extracts, high (H-BC) and low (L-BC) (poly)phenol concentrations, sweet orange extracts (SO) and fibre-rich...

Cereal products provide 50 % of iron and 30 % of zinc in the UK diet. However, despite having high content, the bioavailability of minerals from cereals is low. This review discusses strategies to increase mineral bioavailability from cereal-based foods. Iron and zinc are localised to specific tissue structures within cereals; however, the cell wal...

A waste-to-protein system that integrates a range of waste-to-protein upgrading technologies has the potential to converge innovations on zero-waste and protein security to ensure a sustainable protein future. We present...

Background Dietary intake of pulses is associated with beneficial effects on body weight management and cardiometabolic health, but some of these effects are now known to depend on integrity of plant cells which are usually disrupted by flour milling. Novel cellular flours preserve the intrinsic dietary fiber structure of whole pulses and provide a...

A waste-to-protein system that integrates a range of waste-to-protein upgrading technologies has the potential to converge innovations on zero-waste and protein security to ensure a sustainable protein future. We present a global overview of food-safe and feed-safe waste resource potential and technologies to sort and transform such waste streams w...

In an interlaboratory study we compare different methods to determine the weight-average molecular weight (Mw) and molecular weight distribution of six cereal beta-glucan isolates of nutritional importance. Size-exclusion chromatography (SEC) with multi-angle light scattering (MALS), capillary viscometry, sedimentation velocity analytical ultracent...

Background Starch is a principal dietary source of digestible carbohydrate and energy. Glycaemic and insulinaemic responses to foods containing starch vary considerably and glucose responses to starchy foods are often described by the glycaemic index (GI) and/or glycaemic load (GL). Low GI/GL foods are beneficial in the management of cardiometaboli...

The glycaemic index (GI) is a food metric that ranks the acute impact of available (digestible) carbohydrates on blood glucose. At present, few countries regulate the inclusion of GI on food labels even though the information may assist consumers to manage blood glucose levels. Australia and New Zealand regulate GI claims as nutrition content claim...

Positive health effects of dietary fibre have been established; however, the underpinning mechanisms are not well understood. Plant cell walls are the predominant source of fibre in the diet. They encapsulate intracellular starch and delay digestive enzyme ingress, but food processing can disrupt their structure. Here, we compare the digestion kine...

Starch is present in many prepared ‘ready-meals’ that have undergone processing and/or storage in frozen or chilled state. Hydrothermal processing greatly increases starch digestibility and postprandial glycaemia. Effects of different heating/drying and cooling regimes on amylolysis have received little attention. Hence, we examined the effects of...

The global rise in obesity and type 2 diabetes has generated significant interest in regulating the glycaemic impact of staple foods. Wheat breads (white or wholemeal) are popular staples, but have a high-glycaemic index, due to the highly digestible wheat starch. Reducing the glycaemic potency of white bread is challenging because the bread-making...

Evidence shows that polyphenols can attenuate postprandial blood glucose responses to meals containing digestible carbohydrate. Polyphenol-rich plant extracts are emerging as potential ingredients in functional foods and/or beverages despite limited understanding of their physiological effects. Many studies have investigated the mechanisms of polyp...

Dietary fibre is a generic term describing non-absorbed plant carbohydrates and small amounts of associated non-carbohydrate components. The main contributors of fibre to the diet are the cell walls of plant tissues, which are supramolecular polymer networks containing variable proportions of cellulose, hemicelluloses, pectic substances, and non-ca...

Tea polyphenolics have been suggested to possess blood glucose lowering properties by inhibiting sugar transporters in the small intestine and improving insulin sensitivity. In this report, we studied the effects of teas and tea catechins on the small intestinal sugar transporters, SGLT1 and GLUTs (GLUT1, 2 and 5). Green tea extract (GT), oolong te...

Endothelial dysfunction is a predictor for cardiovascular disease risk and is a key feature of atherosclerosis. Poor diet quality, including consumption of saturated fat-rich, high-refined carbohydrate snack foods, may have adverse effects on endothelial function. Thus, snack foods, which contribute an average of 20% of energy intake in the UK adul...

Objectives The ATTIS study aimed to investigate whether substituting almonds for typical snacks (high in refined starch, free sugars and saturated fats, and low in fibre) influenced cardiometabolic risk factors. Primary outcomes, endothelial function and liver fat, were measured in healthy adults aged 30–70 y who were habitual snackers and at moder...

Background: There is convincing evidence that daily whole almond consumption lowers blood LDL cholesterol concentrations, but effects on other cardiometabolic risk factors such as endothelial function and liver fat are still to be determined. Objectives: We aimed to investigate whether isoenergetic substitution of whole almonds for control snack...

Pulses are high in protein and dietary fibre but their long preparation time can be a barrier to consumption. We have developed PulseON® – novel pre-cooked cell powders that can be prepared from various legumes and used as functional food ingredients. Techno-functional characteristics and starch digestibility of powders prepared from seven differen...

Many carbohydrate foods contain starch that is rapidly digested and elicits a high Glycaemic Index. A legume ingredient (PulseON®) rich in Type 1 resistant starch (RS1) was recently developed; however, its potential as a functional ingredient when processed into a food product required assessment. PulseON® was used to replace 0, 25, 50, 75, and 100...

The effects of whole almond snack consumption on fasting blood lipids and insulin sensitivity: a randomised controlled trial in adults - Volume 79 Issue OCE1 - V. Dikariyanto, S. E. E. Berry, L. Smith, L. Francis, M. Robertson, E. Kusaslan, M. O'Callaghan-Latham, P. R. Ellis, W. L. Hall

Starch is a major source of carbohydrate in human diets and its over-consumption can contribute to the development of obesity and to an increased risk of cardiovascular disease and type 2 diabetes. Various starch-rich foods in the human diet are digested at different rates and to different extents. Understanding of the reasons for these observed di...

Beta 1-3, 1-4 glucans ("beta-glucans") are one of the key components of the cell wall of cereals, complementing the main structural component cellulose. Beta-glucans are also an important source of soluble fibre in foods containing oats with claims of other beneficial nutritional properties such as plasma cholesterol lowering in humans. Key to the...

Inadequate intake of essential minerals such as iron and zinc is a public health concern in the UK, particularly for girls and young women. Approximately 30% and 50% of the zinc and iron, respectively, in the UK diet is provided by cereals. In wheat, most of the iron and zinc is contained within the aleurone cell layer; however, aleurone is removed...

Oat β-glucan has been shown to play a positive role in influencing lipid and cholesterol metabolism. However, the mechanisms behind these beneficial effects are not fully understood. The purpose of the current work was to investigate some of the possible mechanisms behind the cholesterol lowering effect of oat β-glucan, and how processing of oat mo...

This study compares in vitro and in vivo models of lipid digestion from almond particles within a complex food matrix (muffins) investigating whether the cell-wall barrier regulates the bioaccessibility of nutrients within this matrix. Muffins containing small (AF) or large (AP) particles of almond were digested in triplicate using an in vitro dyna...

Oat mixed-linkage β-glucan has been shown to lower fasting blood cholesterol concentrations due notably to an increase in digesta viscosity in the proximal gut. To exert its action, the polysaccharide has to be released from the food matrix and hydrated. The dissolution kinetics of β-glucan from three oat materials, varying in their structure, comp...

Retrograded starch is known to be resistant to digestion. We used enzyme kinetic experiments to examine how retrogradation of starch affects amylolysis catalysed by porcine pancreatic amylase. Parallel studies employing differential scanning calorimetry, infra red spectroscopy, X-ray diffraction and NMR spectroscopy were performed to monitor change...

The positive effects of dietary fibre on health are now widely recognised; however, our understanding of the mechanisms involved in producing such benefits remains unclear. There are even uncertainties about how dietary fibre in plant foods should be defined and analysed. This review attempts to clarify the confusion regarding the mechanisms of act...

Almond kernels contain phytochemicals and nutrients that potentially have positive health benefits in relation to heart disease, diabetes and obesity. One important mechanism associated with these benefits is an imposed limit on bioaccessibility (release) of nutrients, such as lipids, from almond tissue during mastication and digestion. Recent stud...

Figure S1. Arabidopsis leaf architecture, imaged by placing the leaf directly underneath the ATR crystal with no sample preparation.

Previous studies have provided evidence that the physical encapsulation of intracellular nutrients by cell walls of plant foods (i.e. dietary fibre) plays a predominant role in influencing macronutrient bioaccessibility (release) from plant foods during human digestion. One unexplored aspect of this is the extent to which digestive enzymes can pass...

Infrared microspectroscopy is a tool with potential for studies of the microstructure, chemical composition and functionality of plants at a sub-cellular level. Here we present the use of high resolution bench-top based infrared microspectroscopy to investigate the microstructure of wheat kernels and Arabidopsis leaves. Images of isolated wheat ker...

The aim of this study was to investigate the role of the plant food matrix in influencing the extent of starch gelatinisation during hydrothermal processing, and its implications for starch digestibility. Differential scanning calorimetry (DSC) was used to provide a detailed examination of the gelatinisation behaviour of five distinct size fraction...

Cereal crops, particularly wheat, are a major dietary source of starch, and the bioaccessibility of starch has implications for postprandial glycemia. The structure and properties of plant foods have been identified as critical factors in influencing nutrient bioaccessibility; however, the physical and biochemical disassembly of cereal food during...

Polysaccharides derived from plant foods are major components of the human diet, with limited contributions of related components from fungal and algal sources. In particular, starch and other storage carbohydrates are the major sources of energy in all diets, while cell wall polysaccharides are the major components of dietary fibre. We review the...

Although almonds have a high lipid content, their consumption is associated with reduced risk of cardiovascular disease. One explanation for this paradox could be limited bioaccessibility of almond lipids due to the cell wall matrix acting as a physical barrier to digestion in the upper gastrointestinal tract. We aimed to measure the rate and exten...

Starch is a prominent component of the human diet and is hydrolysed by α-amylase post ingestion. Probing the mechanism of this process has proven challenging, due to the intrinsic heterogeneity of individual starch granules. By means of solution-state NMR, we demonstrate that flexible polysaccharide chains protruding from the solvent-exposed surfac...

Recent studies of the mechanisms determining the rate and extent of starch digestion by α-amylase are reviewed in the light of current widely-used classifications for (a) the proportions of rapidly-digestible (RDS), slowly-digestible (SDS), and resistant starch (RS) based on in vitro digestibility, and (b) the types of resistant starch (RS 1,2,3,4…...

The rate and extent of digestibility of starch was analysed using the logarithm of the slope (LOS) method. Digestibility curves with α-amylase were obtained for starches in their native, gelatinised and 24 h retrograded form. A LOS plot of the digestibility curves was then constructed, which allowed the rate constant (k) and the concentration of th...

Cereals constitute important sources of iron in human diet; however, much of the iron in wheat is lost during processing for the production of white flour. This study employed novel food processing techniques to increase the bioaccessibility of naturally occurring iron in wheat. Iron was localized in wheat by Perl's Prussian blue staining. Soluble...

Studying starch amylolysis kinetics in vitro is valuable for predicting the post-prandial glycaemic response to starch intake. Prediction of starch amylolysis behaviour is challenging however, because of the many physico-chemical factors which influence amylolysis. The Logarithm of Slope (LOS) method for analysis of digestibility curves using first...

Background: The particle size and structure of masticated almonds impact significantly on nutrient release (bioaccessibility) and digestion kinetics. Objectives: To quantify the effects of mastication on the bioaccessibility of intracellular lipid of almond tissue and examine microstructural characteristics of masticated almonds. Design: In a rand...

A number of studies have demonstrated that consuming almonds increases satiety but does not result in weight gain, despite their high energy and lipid content. To understand the mechanism of almond digestion, in the present study, we investigated the bioaccessibility of lipids from masticated almonds during in vitro simulated human digestion, and d...

The cell walls (dietary fibre) of edible plants, which consist of mainly non-starch polysaccharides, play an important role in regulating nutrient bioaccessibility (release) during digestion in the upper gastrointestinal tract. Recent studies have shown that structurally-intact cell walls hinder lipid release from the parenchyma cells of almond see...

The water-soluble, mixed-linkage β-glucan, a form of soluble dietary fibre, is considered the main biologically active component responsible for the capacity of many oat products to lower postprandial glycaemia and fasting plasma cholesterol in human subjects. The present review discusses the physical and chemical properties of oat β-glucan that ar...

This paper reports on the stereo-chemical aspects of the chemical stability of lactose solutions stored between 25 and 60 ºC. The lactose used for the preparation of the aqueous solutions was α-lactose monohydrate with an anomer purity of 96% α and 4% β based on the supplied certificate of analysis (using a GC analytical protocol) which was further...

Infrared microspectroscopy is a tool with potential for studies of the microstructure, chemical composition and functionality of plants at a subcellular level. Here we present the use of high-resolution bench top-based infrared microspectroscopy to investigate the microstructure of Triticum aestivum L. (wheat) kernels and Arabidopsis leaves. Images...

Starch is one of the primary sources of energy in the human diet, and is also used in a wide range of industrial processes, including brewing, bioethanol production, paper manufacture and in the production of biodegradable plastics.

Background: Starch is a main source of carbohydrate in human diets, but differences are observed in postprandial glycaemia following ingestion of different foods containing identical starch contents. Such differences reflect variations in rates at which different starches are digested in the intestine. In seeking explanations for these differences...

There is a clear need for improved methods for the study of the physical changes that occur in slurries and sol–gel systems that have significant water content. In this paper a novel immersion mode material pocket form of dynamic mechanical analysis (IMP-DMA) has been designed, combining material pocket technology to provide physical support to a p...

Ingestion of different foods containing identical amounts of starch can result in very different postprandial rises in blood glucose and insulin concentrations. Limitation of the early rises in blood glucose and insulin levels seems to be beneficial to human health in the long term. Many studies of starch digestion in vitro are made to understand t...

We read with interest the article by Carmody et al., “Energetic consequences of thermal and nonthermal food processing,” an important study of the significance of food processing in hominin nutrition and the evolution of human diet and physiology (1). Although we agree that thermal processing is a key variable in the human evolutionary trajectory,...

Ingestion of different foods containing identical amounts of starch can result in very different postprandial rises in blood glucose and insulin concentrations. Limitation of the early rises in blood glucose and insulin levels seems to be beneficial to human health in the long term. Many studies of starch digestion in vitro are made to understand t...

Almonds contain phytochemicals and nutrients that potentially have positive health benefits in relation to heart disease, diabetes and obesity. One important mechanism associated with these benefits is the bioaccessibility (release) of lipids from the almond tissue during mastication and digestion. Indeed, it has been reported that in human subject...

http://pubs.rsc.org/en/content/chapter/bk9781849735636-00036/978-1-84973-563-6#!divabstract

Binding of hydrothermally processed starch to α-amylase and its relation to the kinetics of enzyme digestion - Volume 71 Issue OCE3 - H. Patel, P. Ellis, P. Butterworth

a b s t r a c t Factors affecting the -amylase-catalysed hydrolysis kinetics of starch are incompletely understood, but are of importance to postprandial metabolism and many industrial processes (e.g. bioethanol production). Also, reports on the role of surface area and amorphous content in influencing amylolysis are conflicting. Binding kinetics o...

α-Amylase catalyses the first step in the digestion of starch, a main source of carbohydrate in the human diet. Amylase present in human saliva was one of the first enzymes ever to be recognised but many puzzles remain about the molecular mechanisms involved in amylolysis of starch and even of the physiological role of the salivary amylase itself....

Fructans are non-digestible carbohydrates with various nutritional properties including effects on microbial metabolism, mineral absorption and satiety. They are present in a range of plant foods, with wheat being an important source. The aim of the present study was to measure the fructan content of a range of wheat, rye and gluten-free breads con...

Starches from WT, lam, and r pea mutants differing in amylopectin/amylose contents (70, 90, and 28% amylopectin, respectively) were used in kinetic studies of pancreatic α-amylase action at 37 °C and for investigations of their supramolecular structure and physicochemical properties during heating. For WT and lam starches, amylase accessibility and...

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Various native starch granules were tested as substrates for porcine pancreatic α-amylase and enzyme kinetic parameters obtained from initial rate studies. Surface area per kg weight values and gelatinisation enthalpies (ΔHgel) for the different granules were measured. ΔHgel was used as an indication of the degree of disorder within the starch gran...

Postprandial lipemia is associated with an acute elevation in oxidative stress, inflammation and impaired vascular function, which is attenuated by the presence of antioxidant vitamins. We previously reported that slow release (low bioaccessibility) of lipid from whole almonds (WA) during digestion, compared with free oil from almond (AO) or sunflo...

In seeking an explanation for biochemical factors that influence the postprandial glycaemic response of starch-containing foods, a study was made of the action of pancreatic α-amylase on wheat starch. Samples containing different amounts of water were processed at 100 °C before use as substrates for amylase. Structural information on the starch sam...

This paper examines how plant food processing techniques developed by hunter-gatherers during the Near Eastern Epipalaeolithic (ca. 23970–11990cal b.p.) may have influenced species selection, eating habits and access to critical nutrients. A case study is presented that investigates how pulverising and thermal treatments affect the tubers of Bolbos...

The ability of many water/electrolyte soluble polymers (WSPs), such as guar galactomannan, to form molecular solutions when dispersed in water is important industrially, for example in food applications, and in controlling the release of drugs in the gastrointestinal tract. Certain WSPs, including guar, are also referred to generically as ‘soluble...