Showing papers in "Food Biotechnology in 1992"
TL;DR: Fungal chitosan had significantly less antibiotic effect than CH and CL, and was shown to be concentration dependent with 0.1 mg/mL more effective than 2.0 and 5.0 mg/ mL.
Abstract: The antibacterial action of chitosan hydroglutamate (CH), chitosan lactate (CL) and chitosan derived from fungal mycelia was examined against both gram‐negative and gram‐positive bacteria. Plate counts indicated inactivation rates of one‐ to five‐log‐cycles within one hour. Fungal chitosan had significantly less antibiotic effect than CH and CL. The antibacterial action of CH and CL was very similar and shown to be concentration dependent with 0.1 mg/mL more effective than 2.0 and 5.0 mg/mL. When CH (or CL) and polygalacturonate were added to cell suspensions, death was prevented, possibly indicating that chitosan complexed with polygalacturonate could not penetrate the cell or disrupt the membrane. Leakage of intracellular components caused by chitosan was determined by exposing lactose‐induced Escherichia coli to chitosan with assay for s‐galactosidase activity indicating that cell permeabilization occurred more extensively at the low chitosan concentrations. Microscopic examination showed that...
883 citations
TL;DR: A procedure for fractionation of baker's yeast was developed, based on an induced cell autolysis, which was possible to obtain simultaneously 156 kg of yeast extract, 576 mkat of invertase, 0.7 kg of ergosterol, and 10.3 kg of glucan from 1000 kg of compressed baker’s yeast.
Abstract: Summary A procedure for fractionation of baker's yeast was developed, based on an induced cell autolysis. After this procedure it was possible to obtain simultaneously 156 kg of yeast extract, 576 mkat of invertase, 0.7 kg of ergosterol (with 97% purity), 0.8 kg of phospholipids (with 70% purity) and finally 10.3 kg of glucan from 1000 kg of compressed baker's yeast (28% dw/w). All isolated preparations were also tested in their respective fields of application with satisfactory results.
35 citations
TL;DR: Callus was initiated from meristematic regions of corms of Crocus sativus L. on Murashige and Skoog's medium (MS) supplemented with 2,4‐dichlorophenoxyacetic acid (2 mg/1) and kinetin (0.5mg/1).
Abstract: Callus was initiated from meristematic regions of corms of Crocus sativus L. on Murashige and Skoog's (1962) medium (MS) supplemented with 2,4‐dichlorophenoxyacetic acid (2 mg/1) and kinetin (0.5 mg/1). Somatic embryogenesis was obtained on transfer of callus to MS medium supplemented with indole‐3‐acetic acid (2 mg/1), kinetin (2 mg/1) and ascorbic acid (100 mg/1). The globular embryos on 1/2 strength MS liquid medium with 1 mg/1 abscisic acid showed further differentiation. Adventitious shoots were obtained from callus on MS medium with naphthaleneacetic acid (2 mg/1) and kinetin (4 mg/1). Plantlet formation was obtained from globular callus cultured using filter paper support in liquid medium containing MS basal salts with indole‐3‐acetic acid (2 mg/1), kinetin (2 mg/1) and ascorbic acid (100 mg/1). Embryonal callus mass and shoot forming callus were examined histologically.
34 citations
TL;DR: In this article, several characteristics of bacteriocins which are inhibitory to Clostridium botulinum and Listeria monocytogenes were reported, including the molecular weight of plantaricin BN appeared greater than 10,000, that of bavaricIN MN 22,600, and that of pediocin A 11,000.
Abstract: We report here several characteristics of bacteriocins which are inhibitory to Clostridium botulinum and Listeria monocytogenes. Plantaricin BN produced by Lactobacillus plantarum BN, bavaricin MN produced by Lactobacillus bavaricus MN, and pediocin A produced by Pediococcus pentosaceus 43200 all demonstrated a bactericidal mode of action and retained some activity after heating at 60°C for ten minutes or 100°C for 5 minutes. pH and temperature optima for production on solid media were pH 7.9 and 15°C for plantaricin BN, pH 6.5 and 30°C for bavaricin MN, and pH 6.15–7.9 and 30°C for pediocin A. The molecular weight of plantaricin BN appeared greater than 10,000, that of bavaricin MN 22,600, and that of pediocin A 11,000. All of these bacteriocins were produced during the growth phase of the bacterial cultures.
27 citations
TL;DR: In this paper, the HPLC analysis indicated the presence of 17 amino acids (Asp, Glu, Ser, Thr, Arg, Gly, Ala, Pro, Val, Met, Leu, Ile, Phe, Cys, Lys, His and Tyr, proline being the most abundant) and 7 sugars (ribose, xylose, fructose, mannose, gluc...
Abstract: Abtract Crustacean waste generated from the fishing industry represents approximately 70% of the total landings. This abundant waste may pose an environmental hazard due to the ease of deterioration of the fish tissue in the landfill sites; disposing of the waste, however, can be achieved at considerable cost to the industry; alternatively, the waste can be utilized by extracting useful components and incorporating them Into desirable seafood products. In order to achieve a better management of shellfish waste, the composition of the raw and cooked waste should be determined and economically viable methodologies developed, to extract the important components. Proximate analysis of the commercial shrimp waste indicated the presence of 94.6 % protein and 4.2% fat on dry basis. The HPLC analysis indicated the presence of 17 amino acids (Asp, Glu, Ser, Thr, Arg, Gly, Ala, Pro, Val, Met, Leu, Ile, Phe, Cys, Lys, His and Tyr, proline being the most abundant) and 7 sugars (ribose, xylose, fructose, mannose, gluc...
26 citations
TL;DR: The best medium composition for production of intracellular Iipase by Rhizopus delemar contained oleic acid and no glucose, and it was found that the degree of hydrolysis of olive oil and the flavor profile of lipolyzed milk fat could be easily controlled.
Abstract: The best medium composition for production of intracellular Iipase by Rhizopus delemar contained oleic acid and no glucose. The technique of cell immobilization using polyurethane foam biomass support particles was studied as a means of further enhancing intracellular lipase activity. Fungal mycelia were found to strongly adhere to the polyurethane foam matrix during growth to form immobilized cell biocataiysts, which, after cell membrane permeabiiization and drying, exhibited a Iipase activity 3.3 times greater than that of cells grown in a freely suspended state. Upase within the Immobilized cells showed properties similar to purified extracellular Rhizopus delemar lipase but was more thermostable than the free enzyme. The biocatalyst was used for triglyceride hydrolysis in a continuous stirred‐tank reactor. In this format it was found that the degree of hydrolysis of olive oil and the flavor profile of lipolyzed milk fat could be easily controlled.
19 citations
TL;DR: Chitosan was used as a basis for a fluorescence sensor to monitor volatile malonaldehyde production during lipid oxidation as mentioned in this paper, and three processes were involved in the fluorescence formation.
Abstract: Chitosan was used as a basis for a fluorescence sensor to monitor volatile malonaldehyde production during lipid oxidation. The rate of chitosan fluorescence formation during exposure to volatiles generated during lipid oxidation depended on the extent of fluorescence formation to the one half power and had an activation energy of 13 kcal/mole. Three processes were involved in the fluorescence formation. The rate of volatile malonaldehyde generation during lipid oxidation depended on the extent of malonaldehyde formation to the one half power and had an activation energy of 14 kcal/mole. Malonaldehyde sorption on chitosan powder was immediate and independent of temperature. Chitosan fluorescence formation after exposure to volatile malonaldehyde proceeded at a constant rate and had an activation energy of 13 kcal/mole.
17 citations
TL;DR: It was found that the optimal cooling rate depends mainly on cell properties (size, membrane structure) and the influence of the physiological state of the microorganisms and the application of protection media was investigated.
Abstract: The influence of the cooling rate on the survival of microorganisms (Lactobacillus plantarum, Escherichia coli, Candida boidinii) during freeze drying was studied. It was found that the optimal cooling rate depends mainly on cell properties (size, membrane structure). Additionally, the influence of the physiological state of the microorganisms and the application of protection media (glycerol, skim milk powder) was investigated.
13 citations
TL;DR: This paper showed that xanthan with or without acylation shows marked differences in synergis-tic gelling with plant gluco-mannans, although the polysaccharides with different acylated patterns show similar viscosity.
Abstract: Microbial exopolysaccharides with potential for food usage, frequently carry acyl groups which may profoundly affect their interactive properties. Thus xanthan with or without acylation shows marked differences in synergis‐tic gelling with plant gluco‐ and galacto‐mannans, although the poly‐saccharides with different acylation patterns show similar viscosity. Similarly gellan from Auromonas elodea is of greater potential value after deacetylation, when it provides a valuable gelling agent, than it is as a viscosifier in the natural acylated form. The Enterobacter XM6 polymer only forms gels when it, too, has been chemically deacetylated. Both these polysaccharides form gels due to the enhanced interaction with cations following deacylation. Recent work in our laboratory suggests that deacetylation of certain bacterial alginates also significantly increases ion binding.
12 citations
TL;DR: Comparative studies carried out at the same cell loading and under identical operational conditions indicated that adhered cells were more efficient than calcium alginate entrapped cells for the inversion of sucrose.
Abstract: Yeast cells containing invertase were immobilized on cotton thread waste through adhesion using polyethylenimine (PEI). Cells adhered strongly and were not eluted by change in temperature, ionic concentration or on continuous use for the hydrolysis of sucrose syrup. About 4.4 g of cells could be bound to 10 g of cotton thread. The cotton threads (30 g) containing adhered cells were used in a packed bed column for the continuous hydrolysis of 60% (w/v) sucrose syrup at the rate of about 67 kg per month. At an operational temperature of 45'C the column did not show any decrease in activity for over a month. However, higher temperatures drastically reduced the operational half life of the system. Comparative studies carried out at the same cell loading and under identical operational conditions indicated that adhered cells were more efficient than calcium alginate entrapped cells for the inversion of sucrose.
12 citations
TL;DR: In this paper, the acid and flavor-forming properties of Lactobacillus plantarum and Leuconostoc mesenteroides isolated from Sikhae, a Korean traditional lactic acid fermented fish product, were examined.
Abstract: The acid‐ and flavor‐forming properties of Lactobacillus plantarum and Leuconostoc mesenteroides isolated from Sikhae, a Korean traditional lactic acid fermented fish product, were examined and compared to those of Lactobacillus casei and Lactococcus lactis subsp. diacetylactis DRC3. The effects of prefermentation of rice flour in solid‐state with Bacillus laevolacticus and Saccharomyces‐cerevisiae, extrusion cooking and addition of soymilk as the substrate of lactic acid fermentation vere tested. Extrusion cooking and prefermentation of rice increased the soluble solid and sugar contents before malt digestion. The amount of sugar consumption during lactic fermentation varied with the type of bacteria. Leuconostoc mesenteroides(sikhae) and Lactobacillus plantarum(sikhae) increased up to 6 times of original cell number by 24 hrs of fermentation in rice + soymilk substrate, but Lactococcus lactis decreased in the same substrates. The final pH of the cereal lactic beverage was in the range of 3.4 ‐ ...
TL;DR: In this paper, two models were used to describe the maceration process mathematically, and it was concluded that the process is limited by diffusion of the enzyme through the tissue and blanching has a positive effect on the effective diffusion.
Abstract: Two models were used to describe the maceration process mathematically. The velocity constant k in Model 1 describes the velocity with which potatoes are transformed into macerate, and the velocity constant k, in Model 2 the velocity with which the radius of a spherical potato piece decreases in time. From the results it is concluded that the maceration process is limited by diffusion of the enzyme through the tissue and, also that blanching has a positive effect on the effective diffusion.
TL;DR: In this article, simple sugars were used as C-sources to test whether the chosen Aspergillus niger strain was able to synthesize pectolytic enzymes in a substrate without pectic substances.
Abstract: Simple sugars were used as C‐sources to test whether the chosen Aspergillus niger strain was able to synthesize pectolytic enzymes in a substrate without pectic substances. The most promising results were obtained on commercial sugar (sucrose) which was previously deionized by using a cation exchange resin. Some pectolytic activities such as pectinesterase (PE) and pectin lyase (PL) were similar to those obtained when using a pectin containing substrate. Apple juice depectinizing (AJDA) activity and polygalacturonase (PG) were considerably higher in the sucrose medium. By increasing the sugar concentration from 1.5% to around 15%, the activities increased as follows: AJDA from 15 up to 750 U/ml, PG from 1.8 up to 20 U/ml and PL from 0.14 to 0.65. PE activity was not affected by the sugar concentration. With 14% sugar and other substrate constituents proportionally increased, no benefit was observed with respect to pectolytic activities.
TL;DR: In this article, the effect of y−alumina pellets on volatiles formed in its presence as promoting material at molasse fermentations is also reported, in comparison with those obtained in sugar beet Molasse.
Abstract: The formation of acetaldehyde, ethyl acetate, propanol‐1, 2‐methyl‐propanol‐1, 2‐methyl‐butanol‐1, 3‐methyl‐butanol‐1 in repeated batch alcoholic fermentations of raisin extract by Immobilized Saccharomyces cerevisiae on mineral supports y‐alumina and kissiris was mainly studied. It was found that the fine aroma appeared in the products obtained by the fermentations performed by y‐alum1na supported b1ocatalysts, is attributed to the reduction of the concentration of amyl alcohols, total volatiles determined as well as in the increase of ethyl acetate. Kissiris supported biocatalyst increases the concentrations of volatiles determined. Furthermore, the effect of y‐alumina pellets on volatiles formed in its presence as promoting material at molasse fermentations is also reported. Finally, the formation of volatiles in raisin extract alcoholic fermentations, in comparison with those obtained in sugar beet molasse was examined.
TL;DR: Maize plants growing in the field and maize seeds germinating in the greenhouse were treated with 10mM N‐carboxy‐methylchitosan (NCMC) solutions and NCMC doubled both the zein and the cellular RNA contents of the maize.
Abstract: Maize plants growing in the field and maize seeds germinating in the greenhouse were treated with 10mM N‐carboxy‐methylchitosan (NCMC) solutions. The field‐grown NCMC‐treated maize seeds had a higher zein content (6.3%) than control maize seeds (3.0%). Two temperatures (25°C and 35°C) were used for seed germination. At 35°C, the NCMC‐treated seedlings had a higher zein content (5.6%) than the control seedlings (1.8%). Also the NCMC‐treated seedlings had a higher total cellular RNA content (20.6 μg/g) than the control seedlings (11.0 μg/g). Therefore NCMC doubled both the zein and the cellular RNA contents of the maize.
TL;DR: The relation between the viability of commercial dried wine yeasts and their lipid composition and fatty acid profiles was studied in this paper, where loss of viability was correlated with a high content of partial acylglycerols and free fatty acids in the cells.
Abstract: The relation between the viability of some commercial dried wine yeasts and their lipid composition and fatty acid profiles was studied. Loss of viability was correlated with a high content of partial acylglycerols and free fatty acids in the cells. On the other hand, the beneficial effect of monoenes in the phospholipid fraction on the survival of yeasts exposed to air was observed.
TL;DR: HPLC analysis of the hydrolysate obtained following the saccharification of liquefied tapioca starch with soluble and immobilized amyloglucosidase showed the presence of only glucose and maltose, indicating the relatively low DX observed in the case of soluble enzyme at 24 h was due to the incomplete hydrolysis of the substrate.
Abstract: Studies were carried out to evaluate the probable cause for the prolonged saccharification time required by the soluble enzyme to attain 96–98% DX (w/w). HPLC analysis of the hydrolysate obtained following the saccharification of liquefied tapioca starch with soluble (24 h and 40 h) and immobilized (24 h) amyloglucosidase showed the presence of only glucose and maltose. In the absence of any α‐1,4 and α‐1,6 linked reversal products, the relatively low DX (90–92%) observed in the case of soluble enzyme at 24 h was due to the incomplete hydrolysis of the substrate.
TL;DR: The influence of spray drying on the permeability of the K. fragilis cells was studied and results indicated that the degree of cell permeability was related to the drying temperature.
Abstract: The influence of spray drying on the permeability of the K. fragilis cells was studied. Inlet air temperature and yeast cell concentration were varied in the spray drying process. The degree of cell permeability was evaluated through the intra cellular detection of s‐galactosidase activity. Results indicated that the degree of cell permeability was related to the drying temperature. Additionally, the spray dried cells were observed with the scanning electron microscope. The structure of permeabilized spray dried cells is discussed in reference to the drying mechanism.