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Structures and phenomena occurring during the heat treatment of cornstarch. The structure of cornstarch and the modifications induced during the heat treatments are presented in this review. Current knowledge indicate that the starch granules are semi-crystalline entities composed mainly by amylose and amylopectin, undergoing deep reorganizations during the heat treatments. Gelatinization, glass transitions, relaxation phenomena, retrogradation and the formation of amylose-lipids complexes are the major phenomena involved in these reorganisations, and are the basis of changes of the techno-functional properties of cornstarch-based products during their heat treatment. La rhizosphère est le volume du sol situé au voisinage immédiat des racines des plantes et qui se caractérise par la présence d'exsudats racinaires (rhizodépôts). Ces exsudats sont utilisés par la microflore endémique en tant que signaux chimiques en plus d'être un substrat nutritif disponible pour la croissance et le développement de ces microorganismes dans la rhizosphère. Certaines de ces bactéries du sol, appelées PGPRs (Plant Growth Promoting Rhizobacteria), sont capables de coloniser les racines ou bien encore la rhizosphère, mais à la différence des autres bactéries rhizosphériques elles ont, en retour, un effet bénéfique sur la plante. Cet effet bénéfique peut être direct, ou indirect. La promotion directe de la croissance est le résultat du pouvoir d'acquisition des nutriments ou de la stimulation des hormones de la plante. D'autres mécanismes indirects, mais le plus souvent liés à la croissance des plantes, sont impliqués dans la réduction/suppression des pathogènes des plantes. Cet article décrit les différents mécanismes mis en jeu par les PGPRs dans leur environnement naturel pour influencer favorablement la croissance et la santé des plantes.

Prebiotic isomaltooligosaccharide (IMO) preparations contain α-D-glucooligosaccharides and their structure is the key factor for their prebiotic potential. The transglucosylation selectivity is known to depend on the enzyme specificity and moreover, maltose and α-glucooligosaccharides can actually act as both glucosyl donor and acceptor in the reaction. Thus, two commercial enzymes, a glucosyltransferase and an α-glucosidase, were tested alone and in combination on pure maltose to study their specificities and the IMO profile obtained. The reactions were monitored using a step-forward AEC-PAD analytical method which permitted to detect and resolve new unknown IMO. Structural determination of unknown IMO was attempted using their retention times and relative abundance. As a general rule, the α-glucosidase has a more expressed hydrolyzing activity leading to products containing less residual digestible α-(1-4) linkages such as isomaltose, isomaltotriose, isomaltotetraose, kojibiose and nigerose while the glucosyltransferase produces important amount of panose. Finally, the combination of the two enzymes leaded to an intermediate IMO profile. IMO syrups composition was thus proved to be dependant on the specificity of the transglucosylating enzyme so that products profiles can be designed using different enzymes and in different proportion.

Glass transition phenomena applied to powdered amorphous food carbohydrates. During these last fifteen years, some food technologists and scientists have become aware of the importance of the glass transition, a thermal property of glassy or amorphous material, in food preparation processes. Recent studies have successfully correlated this fundamental notion to technofunctional changes within the powder. The aim of this paper is to present in a non exhaustive manner the relationship between glass transition characteristics and applications in food technology (caking, alterations, etc.).

Sugar esters : ways of synthesis and potential applications [a review]. Sugar esters are nonionic surfactants and exhibit relevant properties as structural diversity and environmental and health safety. Their potential applications extend from human food to drugs formulation and biochemical studies. Some sugar esters also exhibit interesting biological activities. A lot of papers have been submitted during the last ten years. Those articles describe the various ways of synthesis of those compounds at the laboratory scale. During the last ten years, the most studied method was the biotechnological way using enzyme as a catalyser.

Composite breads based on sorghum-wheat flour blends and textural analysis. Breadmaking properties of flour blends containing various levels of sorghum flour with wheat flour were investigated. Good quality bread (loaf volume, crumb structure, external appearance) comparable to bread entirely made from wheat flour could be produced with a level of incorporation of sorghum flour up to 30/. Beyond this level, the loaf volume decreases and the internal characteristics of crumb are deteriorated. The staling of bread made with composite flour is also influenced by the level of substitution of sorghum flour: the more important this level, the higher the rate of crumb firming. Addition of 0.5/ emulsiflers, DATEM and SSL, to the sorghum flour blends improves the crumb characteristics and consequently delays the bread firmness.

Objective: The present study aimed to investigate effect of addition date seed powder on the chemical composition, rheological properties, diffraction scanning colorimetric, x-ray diffraction, infra-red (IR), flavonoid, antioxidant activity, total phenolic compounds and sensory evaluation of snack from them. Methodology: Raw materials (oat and date seed flour) and snacks were analyzed for their proximate composition, rheological (rapid viscoanalyzer and following number), physical properties, color and texture were subjected to measurements using Differential Scanning Calorimetery (DSC). Each sample was tested for its color, flavor, taste, crispness, appearance and overall acceptability. Results: The obtained results revealed that, incorporation of date seed powder resulted in a significant increase in fibre and ash contents and in a decrease in protein content. Increasing DS levels in snacks led to increase the falling …