Osmotic dehydration of pomegranate seeds (PUNICA GRANATUM L.)

Poster (2013, May 30)

Osmotic dehydration of pomegranate seeds was carried out at different temperatures (30, 40, 50°C) in a 55°Brix solution of sucrose, glucose, and mixture sucrose & glucose (50:50 wt/wt). The most ... [more ▼]

Osmotic dehydration of pomegranate seeds was carried out at different temperatures (30, 40, 50°C) in a 55°Brix solution of sucrose, glucose, and mixture sucrose & glucose (50:50 wt/wt). The most significant changes of water loss and solids gain took place during the first 20 min of dewatering. During this period, seeds water loss was estimated to 46% in sucrose, 37% in glucose and 41% in mix glucose/sucrose solution. The increase of temperature favoured the increase of water loss, weight reduction, solids gain and effective diffusivity. Differential scanning calorimetry data provided complementary information on the mobility changes of water and solute in osmodehydrated pomegranate seeds. The ratio between % frozen water and % unfreezable water decreased from 5 to 0.5 during the process. That involving the presence of very tightly bound water to the sample, which is very difficult to eliminate with this process. It also appeared that glass transition temperature depends on the types of sugar. [less ▲]

Effect of air-drying conditions on physical and nutritional properties of osmotically pre-treated pomegranate seeds

Poster (2012, June 01)

EFFECT OF DATE FLESH FIBER CONCENTRATE ADDITION ON DOUGH PERFORMANCE AND BREAD QUALITY

in JOURNAL OF TEXTURE STUDIES (2011), 42(4), 300-308

Date flesh fiber concentrate (DFFC) of Deglet Nour variety were extracted and incorporated in a bakery product. Dough rheological characteristics showed that water absorption, stability, index quality ... [more ▼]

Date flesh fiber concentrate (DFFC) of Deglet Nour variety were extracted and incorporated in a bakery product. Dough rheological characteristics showed that water absorption, stability, index quality, resistance to deformation increased with the amount of added fiber, whereas degree of softening and extensibility decreased in all levels of fiber. Bread evaluation revealed that DFFC addition caused an increase of bread yield especially for the highest levels, a change of crumb color and an insignificant decrease of bread volume. Breads are subjected to sensory evaluation for odor, taste, crumb color, crumb smoothness and overall acceptability. Significant differences were not found (P > 0.05) between scores for all sensory parameters. [less ▲]

PRODUCTION OF XANTHAN GUM FROM XANTHOMONAS CAMPESTRIS NRRL B-1459 BY FERMENTATION OF DATE JUICE PALM BY-PRODUCTS (PHOENIX DACTYLIFERA L.)

in Journal of Food Process Engineering (2011), 34(2), 457-474

In this work, we studied the possibility to use date juice for xanthan gum production by Xanthomonas campestris NRRL B-1459. The results showed that this strain has a high ability to metabolize date juice ... [more ▼]

In this work, we studied the possibility to use date juice for xanthan gum production by Xanthomonas campestris NRRL B-1459. The results showed that this strain has a high ability to metabolize date juice. The data on optimization of physiological conditions of fermentation, pH, temperature, inoculum's size, glucose and nitrogen concentration showed that the maximum xanthan yield of 24.5 g/L was obtained from 60 g/L glucose, 3 g/L ammonium sulphate when batch fermentation was carried with 5% inoculum's size at pH 7, 28C, 48 h, on a rotary orbital shaker at 180 rpm. The polysaccharide purified by high performance liquid chromatography and analyzed by thin layer chromatography contained glucose, glucoronic acid and mannose. PRACTICAL APPLICATIONS Agri-food by-products rich in sugars may be used to produce high added value food ingredients such as xanthan gum. No work has studied the production of this polysaccharide from date. This study is focused on given value addition to date by-product (hard texture) by production of xanthan gum. The effect of several parameters (pH, temperature, inoculum's size, agitation speed, nitrogen source and carbon concentration) on production yield was investigated. [less ▲]

Synthèse des connaissances sur la déshydratation osmotique

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(1), 131-144

Among the preservation processes of vegetal products, osmotic dehydration presents an economic and a nutritional interest. This technique consumes a low quantity of energy, prolongs the period of ... [more ▼]

Among the preservation processes of vegetal products, osmotic dehydration presents an economic and a nutritional interest. This technique consumes a low quantity of energy, prolongs the period of availability of foodstuffs, and gives new and appreciated sensory properties to products. Therefore, the producers can sell their productions at better prices and the consumers are able to consume fruits and vegetables throughout the year. This technique is very easy to set up, especially in the developing countries due to its low cost. The aim of this article is to present a synthesis of the literature concerning the osmotic dehydration technique, and also to specify the new tendencies and directions of recent research. [less ▲]

Synthèse des connaissances sur la déshydratation osmotique

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(1), 129-142

Parmi les procédés de conservation des produits végétaux, la déshydratation osmotique présente un intérêt économique et nutritionnel certain. Cette technique, économe en énergie, est susceptible de ... [more ▼]

Parmi les procédés de conservation des produits végétaux, la déshydratation osmotique présente un intérêt économique et nutritionnel certain. Cette technique, économe en énergie, est susceptible de prolonger la période de disponibilité des produits alimentaires et leur confère des propriétés sensorielles nouvelles et appréciées. Elle permet ainsi aux acteurs de la filière agro-alimentaire d’écouler leurs productions à de meilleurs prix et aux consommateurs d’en disposer tout au long de l’année. Cette technique est un outil facile à mettre en place, surtout dans les pays en voie de développement, en raison de son faible cout. Le présent article a pour objectif de présenter une synthèse de la littérature concernant la technique de déshydratation osmotique afin d’en rappeler les bases théoriques et pratiques, mais aussi d’en préciser les nouvelles tendances et voies de recherches récentes. [less ▲]

Utilisation du jus de datte comme milieu d’immersion pour la déshydratation osmotique des graines de grenade

Poster (2010, October 14)

Osmotic Dehydration Kinetics of Pomegranate Seeds Using Date Juice as an Immersion Solution Base

in Food and Bioprocess Technology (2010)

Pomegranate seeds were osmodehydrated using date juice added with sucrose (final °Brix, 55) as immersion solution. The kinetics of osmotic dehydration showed that the most significant changes of mass ... [more ▼]

Pomegranate seeds were osmodehydrated using date juice added with sucrose (final °Brix, 55) as immersion solution. The kinetics of osmotic dehydration showed that the most significant changes of mass transfer took place during the first 20 min of the process, regardless of date juice varieties. During this time, seed water loss and solid gain were estimated to be ∼39% and ∼6%, respectively. After 20 min of the process, the percentage of water loss and solid gain varied slightly and ranged on average close to ∼40% and ∼9%, respectively. During osmotic dehydration, there was a leaching of natural solutes from seeds into the solution, which is quantitatively not negligible, and might have an important impact on the sensorial and nutritional value of seeds and date juices. Both scanning electron microscopy and texture (compression) analysis revealed that osmotic dehydration process induced modifications of seed texture and cell structure. Sucrose was found to be the essential element which influences the texture of seed and the viscosity of date juice. Additionally, natural sugar present in date juice permits substituting 35% of the total quantity of sucrose added to the osmotic solution. [less ▲]

Characterisation of proteins from date palm sap (Phoenix dactylifera L.) by a proteomic approach

in Food Chemistry (2010)

The proteins contained in juice tapped from date palm (Phoenix dactylifera L.), from Deglet Nour variety, were analysed by the application of two-dimensional electrophoresis (2DE). Identification was ... [more ▼]

The proteins contained in juice tapped from date palm (Phoenix dactylifera L.), from Deglet Nour variety, were analysed by the application of two-dimensional electrophoresis (2DE). Identification was carried out by mass spectrometry analyses. The SDS–PAGE patterns showed more than 100 spots of which 52 spots were identified. A proportion of the identified proteins were related to Saccharomyces cerevisiae that may belong to the natural microflora of date palm sap. These proteins are principally involved in glycolysis. While other proteins were assigned to be vegetable proteins, probably a mixture of proteins from the vascular system, which have several biological functions within the palm tree. Thus, we found enzymes involved in stress and defence reactions, in glycolysis, and photosynthesis reactions. Other enzymes are associated with carbohydrates and proteins metabolisms. [less ▲]

Pectin extraction from lemon by-product with acidified date juice : effect of extraction conditions on chemical composition of pectin.

in Food Science & Technology International (2010), 16(2), 105-114

The microstructure and the rheological properties of lemon-pectin mixtures were studied and compared to those of pure lemon (high methoxyl: HM) and date (low methoxyl: LM) pectins. Rheological properties ... [more ▼]

The microstructure and the rheological properties of lemon-pectin mixtures were studied and compared to those of pure lemon (high methoxyl: HM) and date (low methoxyl: LM) pectins. Rheological properties were carried out in the presence of 30%, 45% and 60% sucrose, and increasing calcium concentrations (0-0.1%). The presence of date with lemon pectin led to a gel formation at 45% sucrose and in the presence of calcium, which was not the case for lemon pectin alone under the same conditions. It is suggested that lemon and date pectins interacted, leading to gel formations at different gelling temperatures, which were strongly dependant on degree of methylation. These results were confirmed by scanning electron microscopy, which revealed inhomogeneous gels where dense aggregated network and loose, open network areas were present. Addition of calcium to pectin mixture gels led to stronger and faster gel formation. [less ▲]