In this review the quality properties of linseed oil for food uses are discussed as well as factors affecting this quality. Linseed oil has a favourable fatty acid composition with a high linolenic acid content. Linseed oil contains nearly 60% α-linolenic acid, compared with 25% for plant oils generally. The content of linolenic acid and omega-3 fatty acids is reported to be high in linseed grown in northern latitudes. The composition of fatty acids, especially unsaturated fatty acids, reported in different studies varies considerably for linseed oil. This variation depends mainly on differences in the examined varieties and industrial processing treatments. The fatty acid composition leads also to some problems, rancidity probably being the most challenging. Some information has been published concerning oxidation and taste, whereas only a few studies have focused on colour or microbiological quality. Rancidity negatively affects the taste and odour of the oil. There are available a few studies on effects of storage on composition of linseed oil. In general, storage and heat promote auto-oxidation of fats, as well as decrease the amounts of tocopherols and vitamin E in linseed oil. Several methods are available to promote the quality of the oil, including agronomic methods and methods of breeding as well as chemical, biotechnological and microbiological methods. Time of harvesting and weather conditions affect the quality and yield of the oil.

ScopeResistance of proteins to gastrointestinal digestion may play a role in determining immune‐mediated adverse reactions to foods. However, digestion studies have largely been restricted to purified proteins and the impact of food processing and food matrices on protein digestibility is poorly understood.Methods and resultsDigestibility of a total gliadin fraction (TGF), flour (cv Hereward), and bread was assessed using in vitro batch digestion with simulated oral, gastric, and duodenal phases. Protein digestion was monitored by SDS‐PAGE and immunoblotting using monoclonal antibodies specific for celiac‐toxic sequences (QQSF, QPFP) and starch digestion by measuring undigested starch. Whereas the TGF was rapidly digested during the gastric phase the gluten proteins in bread were virtually undigested and digested rapidly during the duodenal phase only if amylase was included. Duodenal starch digestion was also slower in the absence of duodenal proteases.ConclusionThe baking process reduces the digestibility of wheat gluten proteins, including those containing sequences active in celiac disease. Starch digestion affects the extent of protein digestion, probably because of gluten‐starch complex formation during baking. Digestion studies using purified protein fractions alone are therefore not predictive of digestion in complex food matrices.

Gluten is a crucial functional component of bread, but the effect of increasing gluten content on gastrointestinal (GI) function remains uncertain. Our aim was to investigate the effect of increasing gluten content on GI function and symptoms in healthy participants using the unique capabilities of MRI. A total of twelve healthy participants completed this randomised, mechanistic, open-label, three-way crossover study. On days 1 and 2 they consumed either gluten-free bread (GFB), or normal gluten content bread (NGCB) or added gluten content bread (AGCB). The same bread was consumed on day 3, and MRI scans were performed every 60 min from fasting baseline up to 360 min after eating. The appearance of the gastric chime in the images was assessed using a visual heterogeneity score. Gastric volumes, the small bowel water content (SBWC), colonic volumes and colonic gas content and GI symptoms were measured. Fasting transverse colonic volume after the 2-d preload was significantly higher after GFB compared with NGCB and AGCB with a dose-dependent response (289 (SEM 96) v. 212 (SEM 74) v. 179 (SEM 87) ml, respectively; P = 0·02). The intragastric chyme heterogeneity score was higher for the bread with increased gluten (AGCB 6 (interquartile range (IQR) 0·5) compared with GFB 3 (IQR 0·5); P = 0·003). However, gastric half-emptying time was not different between breads nor were study day GI symptoms, postprandial SBWC, colonic volume and gas content. This MRI study showed novel mechanistic insights in the GI responses to different breads, which are poorly understood notwithstanding the importance of this staple food.Key words: MRI: Gluten-free bread: Gastric emptying: Colonic volumes: Bloating Bread is one of the most common food items consumed all around the world. In the UK the industrial sector represents 80 % of total production, with a market worth £3·4 billion (1) . The most commonly consumed bread in western countries is wheat bread, of which gluten is a crucial functional component. Gluten is a protein contained in flour that is key to the breadmaking process. Mixing with water causes the gluten to swell and develop a network that gives a viscoelastic dough with the ability to retain gas, a property vital to allow bread to rise (2) . Gluten is largely responsible for the unique texture of wheat bread. In the last few years gluten has gained much more attention because of the increasing phenomenon of people complaining of gastrointestinal (GI) symptoms (altered bowel habit, abdominal pain, bloating and nausea) when they eat wheat, despite not having coeliac disease (CD) (3) . However, little is known about the 'in vivo' effects of bread gluten content on GI physiology. MRI has unique capabilities when it comes to imaging complex food materials during their processing within the GI tract. In a recent study (4) , we compared the upper GI processing of a wholemeal bread (WMB) meal with an equienergetic rice pudding (RP) meal. The MRI appearance of the two study meals inside the stomach was markedly different,...

No abstract

Naked oat grain, which is free from lemma and palea, has high nutritional quality, but the unprotected grain is prone to mechanical damages caused by combine harvesting. Naked oats were grown for 3 years in southern Finland, at Viikki Experimental Farm, University of Helsinki (60m 13hN) to produce seed material for laboratory tests that evaluated : (1) genotypic differences of naked oat in sensitivity to damage during harvesting at grain moisture varying from c. 10 % up to 50 %, (2) the effect of mechanical damage on germination and grain vigour, and (3) grain characteristics contributing to susceptibility to reduced grain viability. In 1997, one naked (Rhiannon) and husked oat cultivar (Salo) were harvested, and in 1998-1999 additional four naked cultivars (Bullion, Lisbeth, Neon, SW 95926) were included. One large plot (14 mi10 m) was sown per cultivar. Two sowing times were used. Fully ripened grains were combine harvested on several occasions for each plot to obtain differences in grain moisture at harvest. Simultaneously, panicle samples were collected, dried and threshed by hand (controls). Grain moisture at each sampling and harvesting was monitored. About 3 months after harvesting, germination tests on blotting paper were carried out. Proportions of normally developed seedlings, seedlings lacking either radicle or hypocotyl, damaged coleoptiles, dead grains and lethally fungus-infected grains were recorded from combine harvested and hand threshed samples on different cultivars and harvest moistures. Tests on seedling elongation, seedling emergence through sand (2 cm and 5 cm depth), and ion leakage were applied to evaluate grain vigour. Groat weight, diameter, length, roundness, hardness and protrusion of embryo were determined. Our results indicated that naked cultivars were far more prone to mechanical damages than husked Salo, but differences among naked cultivars in susceptibility occurred. When targeting germination of 75 %, grain moisture at harvest should not exceed 19-26 % depending on cultivar. Abnormal seedlings appeared irrespective of grain moisture at harvest, but the higher the grain moisture, more dead grains were found in harvested grains after storage. Seed vigour did not alter parallel to germination ability. High proportion of small grains in harvested yield and softer groats contributed to decreased sensitivity to mechanical damages.