Greater Storage Stability Research Articles

Stability and Releasing Property of Anthocyanins Microcapsules from <i>Acanthopanax</i><i>. s</i><i>essiliflorus (Rupr. et Maxim.)</i> Seem

Anthocyanins microcapsules from Acanthopanax.sessiliflorus (Rupr. et Maxim.) Seem were prepared by Spray-Drying, using maltodextrin and gum arabic as wall materials. The stability and releasing property of anthocyanins microcapsules were studied. Using the retention rate as evaluation index, the effects of temperature, light, pH and metal ions on the stability of microcapsules and anthocyanins during 30 days storage were assessed, and samples were taken every five days. Results show that the microcapsules have greater storage stability against temperature, light, pH and metal ions. Using the release rate as evaluation index, the effect of releasing of microcapsules was evaluated, and samples were taken every 30min. Results show that the microcapsules have certain slow-release effect.

Acetone powder from dormant seeds of Ricinus communis L

The influence of several factors on the hydrolytic activity of lipase, present in the acetone powder from dormant castor seeds (Ricinus communis) was evaluated. The enzyme showed a marked specificity for short-chain substrates. The best reaction conditions were an acid medium, Triton X-100 as the emulsifying agent and a temperature of 30 degrees C. The lipase activity of the acetone powder of different castor oil genotypes showed great variability and storage stability of up to 90%. The toxicology analysis of the acetone powder from genotype Nordestina BRS 149 showed a higher ricin (toxic component) content, a lower 2S albumin (allergenic compound) content, and similar allergenic potential compared with untreated seeds.

Thermal behavior of pure rice bran oil, sunflower oil and their model blends during deep fat frying

Shall be deleted offer some advantages like better nutritional quality, lower cost and greater storage stability than pure oils. Model blends prepared from pure rice bran oil (RBO) and sunflower oil (SFO) were examined for change in their physico-chemical parameters (acid value, iodine value, color value, peroxide value and fatty acids). Repeated deep fat frying processes were carried out using dried potato chips in pure rice bran oil, sunflower oil and their model blends, in order to study the thermal behavior of pure rice bran oil, sunflower oil and their model blends. Pure rice bran oil and sunflower oil showed good thermal stability during the repeated deep fat frying cycles. Although all the blended oils used in the study showed good thermal stability during repeated deep fat frying cycles, model blends consisting of 60%RBO + 40% SFO showed better suitability during repeated deep fat frying than the remaining blended oils.

Gelatin blends with alginate: Gel fibers for α-galactosidase immobilization and its application in reduction of non-digestible oligosaccharides in soymilk

α-Galactosidase from Aspergillus oryzae was physically entrapped in gelatin blended alginate hydrogel fibers hardened with glutaraldehyde. Immobilization yield resulted in 71.75%. The optimum conditions were not affected by immobilization, and the optimum pH and temperature for free and immobilized enzyme were 4.8 and 50 °C, respectively. Immobilized α-galactosidase was more stable at higher pH and temperature. To improve the immobilization system polyols like glycerol (C 3) was used with different amounts of Na-alginate and gelatin. The free α-galactosidase activity quickly decreased and the half time of the activity decay was about 5 days at 4 °C. The immobilized enzyme remained very active over a long period of time and this enzyme lost about 70% of its original activity over the period of 60 days for storage at 4 °C. Immobilized α-galactosidase was used in batch, repeated batch and continuous mode to degrade the non-digestible oligosaccharides present in soymilk. The performance of immobilized α-galactosidase was also tested in a fluidized bed reactor at different flow rates and 93% reduction of NDO in soymilk was obtained at 25 ml h −1 flow rate. The study revealed that alginate–gelatin fiber entrapped α-galactosidase shows the higher immobilization yield, greater storage stability and better percent hydrolysis of NDO present in soymilk compared to alginate and gelatin entrapped α-galactosidase.

Immobilization of urease on cation-exchange membranes prepared by radiation-initiated graft copolymerization of acrylic acid on polyethene thin films

A covalent immobilization of urease was conducted on carboxylic cation-exchange membranes (CEM) prepared by radiation-initiated graft copolymerization of acrylic acid (AA) on polyethene (PE) thin films. Six types of CEM with different grafting degree (from 26.5 to 95.2%) were used as carry. The carboxyl groups were activated by the carbodiimide method in order to carry out a covalently immobilization. The amount of bound protein and the enzyme activity were determined in each immobilized system. It was established that the urease, immobilized on CEM with 64.2% grafting degree, featured the highest relative activity – 80.32%. The amount of bound protein on this membrane type was 6.01 mg/cm2. The basic characteristics of the immobilized and the free enzymes were determined (pHopt, Topt and pHstab). It was found out that the immobilized urease had greater thermal and storage stability in comparison with the free enzyme. It was proven that CEM with a grafting degree of 64.2% would be a suitable carrier for urease immobilization.

Biochemical properties of soybean leaf lipoxygenases:Presence of soluble and membrane-bound forms

Lipoxygenases (EC 1.13.11.12, LOX) extracted from soybean leaves ( Glycine max [L.] Merrill cv. IAC-100) at pH 6.5 showed low stability. Given the importance of correlating the biochemical roles with the physiological characteristics of each LOX isoenzyme, this work evaluates biochemical characteristics and stability conditions of these enzymes in order to plan a purification procedure. LOX activity (A 234 at pH 6.0) increased four to five times when 0.25 % (v/v) Triton X-100, 1 % (w/v) polyvinylpyrrolidone, and 1 mM phenylmethylsulfonyl fluoride were added to leaf macerates. Fe 2+ (1 mM) stabilised LOX (70.3 % of activity recovered after 48 h storage). Ammonium sulphate fractionation (35–65 % saturation) increased specific LOX activity five times and stabilised the enzymes. Two optimum LOX activities were observed at pH 6.0–6.5 and 4.0–5.0, and the greater storage stability was at pH 6.5 (after 24–28 h storage at different pH values). The results suggest the presence of at least two different forms of the enzyme. The forms of LOX that are active at acidic pH are more stable than the ones that are active at neutral pH. These stable forms were extracted in absence of detergents (soluble forms), while the forms of LOX that are active at pH 6.0–6.5 are unstable forms specially extracted in presence of Triton X-100, and possibly correspond to membrane-bound proteins.

Extracellular invertase from Aspergillus athecius: Isolation and immobilization

A fungal strain isolated from soil and identified asAspergillus athecius, when grown on moistened wheat bran produced large amounts of extracellular invertase. Most of the invertase from the moldy bran was easily extracted by low ionic strength buffer (0.005 M, pH 5.7). The crude invertase immobilized on DEAE cellulose showed not only increased activity (approxiate 45%) but also greater thermal and storage stability than the free enzyme. The free and the bound enzymes showed a temperature optimum of 50–55°C and a pH optimum of 5.7 and 4.8 respectively. The Km app. of the bound enzyme was lower than that of the free enzyme

Liquid preservation of highly purified human granulocytes

Highly purified human granulocytes isolated from continuous flow centrifugation leukapheresis concentrates by counterflow centrifugation-elutriation were stored at 4 °C in concentrations of 6 × 10 6 to 1 × 10 7 granulocytes per milliliter for up to 14 days. The in vitro physiological function assays of phagocytosis, oxygen consumption associated with phagocytosis, bacterial growth inhibition, chemotaxis, and five enzyme analyses indicated good storage survival for up to 4 days. Stored granulocytes separated from other blood cells have greater storage stability than granulocytes stored as leukapheresis concentrates. After 14 days of storage a small percentage of granulocytes still maintained all physiological functions, with the exception of chemotaxis. Of the five enzymes assayed, only the enzyme activity of leucine aminopeptidase decreased significantly by the 14th day of storage. The storage stability of each physiological function assayed decreased as follows: bacterial growth inhibition (most stable), phagocytosis, oxygen consumption, and chemotaxis (least stable).

Chlorophyll degradation and lipid oxidation in frozen unblanched peas.

AbstractStorage of hand‐podded unblanched frozen peas for 20 months at –9·4° resulted in considerable conversion of chlorophylls to pheophytins, the formation of phytol‐free derivatives, a decrease in total pigment and the formation of peroxides and TBA‐reactive materials. Greater storage stability was found in samples blanched prior to storage, and to a lesser extent in unblanched peas stored in nitrogen or at –23·3°.Lipoxygenase and chlorophyll bleaching activities of extracts from frozen unblanched peas decreased during storage, lipoxygenase being the more stable.Model system studies with pea and soya extracts indicated that chlorophyll loss and lipid oxidation during storage were most likely caused by lipoxygenase and a lipohydroperoxide breakdown factor shown to be present in crude extracts.