L Value (l + value)

Distribution by Scientific Domains


Selected Abstracts


PHYSICAL, PHYSIOLOGICAL AND CHEMICAL CHANGES IN POTATO AS INFLUENCED BY ERWINIA CAROTOVORA INFECTION

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 5 2002
F. NOURIAN
Bacterial soft rot, caused by Erwinia carotovora ssp. carotovora (Ecc), is a major disease in stored potatoes. The pathogen causes different physical, physiological and chemical changes in potatoes, which may affect the acceptability of raw and processed products. This study was carried out to evaluate the effect of disease severity on different physico-chemical and physiological properties of raw and cooked potatoes and to select the parameters most responsive to disease severity. Potatoes were inoculated with bacteria and incubated at 20C for different lengths of time to produce different levels of disease. As incubation time increased the volume of disease (VDS) increased, which in turn influenced the respiration rate (RR). In both raw and cooked potatoes, the physical changes (texture and color) associated with the progress of disease were reduced hardness, firmness and L value, and increased a and b values and total color difference (,E). The chemical changes were reduced ascorbic acid and pH, and increased reducing sugars, total sugars and titrable acidity along with the activities of peroxidase and polyphenol oxidase. The changes in physical and chemical parameters of raw and cooked potatoes during storage were described by fractional conversion equation models. All parameters were quite sensitive to disease except reducing sugars, peroxidase and PPO activity. The correlation matrix indicated that several of the quality parameters were related and thus most of them could be successfully used to predict tuber quality from disease. [source]


PREDICTING SENSORY ATTRIBUTE INTENSITIES AND CONSUMER ACCEPTANCE OF STORED ROASTED PEANUTS USING INSTRUMENTAL MEASUREMENTS

JOURNAL OF FOOD QUALITY, Issue 4 2006
C.M. LEE
ABSTRACT The objective of this study was to predict the sensory properties of stored roasted peanuts using instrumental methods. Roasted peanuts were stored at 20 treatment combinations of temperature (23, 30, 35 and 40C) and water activity (Aw; 0.33, 0.44, 0.54, 0.67 and 0.75 Aw), then evaluated after storing for up to 91 days using descriptive analysis (n = 12) and instrumental methods. Stored samples were also evaluated by consumers (n = 50). Regression models (adj. R2 , 0.70) indicated that increasing storage Aw resulted in decreasing color lightness (L value). Increasing storage time and Aw increased both measured Aw and percent moisture of roasted peanuts. Sensory texture attribute intensities were best predicted by percent moisture (adj. R2 , 0.78), whereas consumer ratings were best predicted (adj. R2 , 0.74) by color or percent moisture. Instrumental texture analyses did not predict descriptive or consumer ratings. While percent moisture was the best predictor of consumer acceptance of stored roasted peanuts, color was an excellent alternative predictor and employed a much simpler assay. [source]


Rhubarb Juice as a Natural Antibrowning Agent

JOURNAL OF FOOD SCIENCE, Issue 8 2000
S.M. Son
ABSTRACT: To search for natural antibrowning agents, rhubarb juice was tested on fresh-cut apple slices and found to have a potent effect. Liberty apple slices were treated in various concentrations of rhubarb juice (5%,100%), and the rate of discoloration at room temperature was measured by a Hunter Colorimeter. Apple slices treated in the 5%, 10% solution showed browning activity with dL values of 2.3 , 2.5 at two hours. However, the concentrations of rhubarb juice above 20% inhibited apple browning effectively with no change in the L value for several hours. Analysis of oxalic acid in rhubarb juice showed that the 20% solution contained about 67 mg/100g. [source]


THE USE OF TOMATO PULP POWDER AS A THICKENING AGENT IN THE FORMULATION OF TOMATO KETCHUP

JOURNAL OF TEXTURE STUDIES, Issue 2 2008
A. FARAHNAKY
ABSTRACT In this current study, tomato pulp powder, the main waste of the tomato processing industry, was used as a thickening agent in the formulation of a commercial tomato ketchup at different levels (1, 2, 5, 7 and 10% w/w). Color parameters (L and a/b) and rheologic properties of the formulated ketchups with and without added tomato pulp powder were determined and compared. The addition of the pulp powder caused a significant increase in the L value of the samples, while a/b ratio decreased notably. The rheologic data obtained were fitted using a power law equation. The analysis of the data obtained revealed that low levels of tomato pulp powder can compete with other hydrocolloids in improving the consistency of tomato ketchup. All ketchup samples in this study were non-Newtonian fluids and the apparent viscosity of the ketchups increased significantly with increasing concentration of tomato pulp powder and decreased with temperature increase. Chemical composition (protein, total fat, reducing and total sugars, fiber, ascorbic acid and ash contents) and some physicochemical properties of the tomato pulp powder, including water absorption and solubility, were determined and the data were used for the interpretation of the rheologic and color changes as a result of the inclusion of the pulp powder in the formulation. PRACTICAL APPLICATIONS The direct use of food industry wastes in food formulations can help in reducing the production costs by decreasing raw material and disposal costs. The classic design of the tomato processing plants results in generating a large amount of tomato pulp. The results of this research confirmed that tomato pulp powder can be used instead of other hydrocolloids in tomato-based products. The reuse of tomato pulp powder in foods can be beneficial to producers and the environment. [source]


PHYSICOCHEMICAL PROPERTIES OF TEXTURIZED MEAT ANALOG MADE FROM PEANUT FLOUR AND SOY PROTEIN ISOLATE WITH A SINGLE-SCREW EXTRUDER ,

JOURNAL OF TEXTURE STUDIES, Issue 4 2004
E.L. PARMER JR.
ABSTRACT The objective of this study was to establish conditions for the texturization of soy protein isolate and peanut flour mixture using a single-screw extruder. The effects of feed moisture, screw-speed, and barrel temperature on the characteristics of the texturized products were studied. Feed moisture was the most important factor affecting the texture. Feeding ingredients with 22% moisture had the highest water absorption and expansion indices, and Hunter L value (P < 0.05). When the screw speed was above 180 RPM, the meat analog had a 12% decrease in the expansion index and a 5% decrease in moisture content (P < 0.05). When the barrel temperature was increased to 165C, there was a 12% decrease in the water absorption index, and a 23% decrease in the expansion index of the meat analogs (P < 0.05). Overall, an acceptable meat analog could be successfully produced with 22% moisture in the raw ingredient, screw speed at 140 RPM, and barrel temperatures at 150, 155, and 160C for the three temperature zones respectively. [source]


A response surface methodology approach to optimise pretreatments to prevent enzymatic browning in potato (Solanum tuberosum L) cubes

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2002
C Reyes-Moreno
Abstract The objective of this work was to find the best combinations of ascorbic acid concentration/soaking time (Pretreatment 1), 4-hexylresorcinol concentration/soaking time (Pretreatment 2) and ascorbic acid concentration,4-hexylresorcinol concentration/soaking time (Pretreatment 3) to prevent the development of enzymatic browning in raw potato cubes (10,mm,×,10,mm,×,10,mm). Potato variety Alpha was used as study model because of its low susceptibility to enzymatic browning. Response surface methodology was applied in all pretreatments on two response variables (Hunter L value and total colour difference) to find the best conditions for carrying out the pretreatments. The various pretreatments had variation levels for ascorbic acid (AA) concentration (1 and 3) and 4-hexylresorcinol (4HR) concentration (2 and 3) of 1,4 and 0.04,0.20,g,l,1 respectively; in all pretreatments the variation level for soaking time was 3,6,h. A central composite experimental design with two factors at five levels was used. Predictive models for Hunter L value and total colour difference were developed as a function of process or independent variables. The optimisation technique was applied to obtain maximum Hunter L values and minimum values of total colour difference. Surface superposition of these variables allowed identification of the best combinations of process variables for each pretreatment as (1) 2.9,g,l,1 AA/4.8,h, (2) 0.04,g,l,1 4HR/2.6,h and (3) 2.42,g,l,1 AA,0.15,g,l,1 4HR/5.41,h. © 2001 Society of Chemical Industry [source]


The effect of aging biosolids on the availability of cadmium and zinc in soil

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2001
S. Stacey
Summary A major concern with the safe re-use of biosolids on land is the potential for release of metals from organic matter in the biosolids, due to decomposition proceeding as biosolids age. To quantify the effects of biosolid aging on Cd and Zn bioavailability, two sewage sludges (Lagoon sludge and Filtered sludge) and a garden compost were incubated at 25°C and 35°C for 100 days. Changes in availability of Cd and Zn were determined using isotope dilution principles, with the materials being labelled with carrier-free 109Cd and 65Zn. We determined isotopically exchangeable metal pools (E values) and plant available metal pools (L values) by measuring specific activities of Cd and Zn in soil extracts and in wheat plants, respectively. Changes in carbon content over time were determined using 13C-NMR spectroscopy and chemical extraction methods, and related to changes in availability of metal pools as determined by isotopic procedures. Hot-water-extractable carbon content, assumed to represent easily decomposable organic matter, decreased during the 100 days by 80,190 mg kg,1. The Compost and Lagoon sludge showed no change in L values for Cd or Zn with time, but in the Filtered sludge the L values for Cd and Zn increased significantly, by 43% and 56%, respectively. The isotopically exchangeable pools of Cd and Zn did not change with incubation treatment of the biosolids. These data indicate that the potential for metal release from biosolids as organic matter decomposes depends to a large extent on the biosolid composition. [source]


EFFECTS OF KERNEL PROPERTIES AND POPPING METHODS ON POPCORN QUALITY OF DIFFERENT CORN CULTIVARS

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 4 2009
NILGÜN ERTA
ABSTRACT Three popcorn genotypes, Koç Cin (composite), Nermin Cin and Ant Cin-98 (hybrid) were investigated for the effects of kernel size (4 < D < 5 and 5 < D < 6), popping methods (conventional and microwave) and moisture content (10, 12 and 14%) on popcorn quality. The relationships between physical kernel properties and popping characteristics were also researched. The Nermin Cin popcorn cultivar had the highest expansion volume, flake size and the lowest percentage of unpopped kernel values among genotypes. 5 > D > 6 mm kernel fraction and the conventional method produced higher popcorn quality in all popcorn cultivars. The optimum moisture levels for the highest expansion volume changed between 12 and 14% for different cultivars. The correlation coefficient between kernel properties (width, sphericity, L, a and b) and expansion volume were found significant (P < 0.01) in microwave popping method. Color a had high direct effects on expansion volume in conventional and microwave popping methods according to path coefficient analysis. L values of popcorn cultivars negatively correlated with expansion volume in both popping methods. PRACTICAL APPLICATIONS Physical parameters like width, sphericity and color values were found important in predicting popping quality. Color values should be used to predict expansion volume instead of classic physical properties for ease ofmeasurement. Conventional popping method, 5 > D > 6 kernel size and 12,14% moisture content parameters should be used for optimum popcorn quality. [source]


A response surface methodology approach to optimise pretreatments to prevent enzymatic browning in potato (Solanum tuberosum L) cubes

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2002
C Reyes-Moreno
Abstract The objective of this work was to find the best combinations of ascorbic acid concentration/soaking time (Pretreatment 1), 4-hexylresorcinol concentration/soaking time (Pretreatment 2) and ascorbic acid concentration,4-hexylresorcinol concentration/soaking time (Pretreatment 3) to prevent the development of enzymatic browning in raw potato cubes (10,mm,×,10,mm,×,10,mm). Potato variety Alpha was used as study model because of its low susceptibility to enzymatic browning. Response surface methodology was applied in all pretreatments on two response variables (Hunter L value and total colour difference) to find the best conditions for carrying out the pretreatments. The various pretreatments had variation levels for ascorbic acid (AA) concentration (1 and 3) and 4-hexylresorcinol (4HR) concentration (2 and 3) of 1,4 and 0.04,0.20,g,l,1 respectively; in all pretreatments the variation level for soaking time was 3,6,h. A central composite experimental design with two factors at five levels was used. Predictive models for Hunter L value and total colour difference were developed as a function of process or independent variables. The optimisation technique was applied to obtain maximum Hunter L values and minimum values of total colour difference. Surface superposition of these variables allowed identification of the best combinations of process variables for each pretreatment as (1) 2.9,g,l,1 AA/4.8,h, (2) 0.04,g,l,1 4HR/2.6,h and (3) 2.42,g,l,1 AA,0.15,g,l,1 4HR/5.41,h. © 2001 Society of Chemical Industry [source]


Morphometric Analysis on the Size, Shape and Areal Distribution of Glacial Cirques in the Maritime Alps (Western French-Italian Alps)

GEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3 2004
Paolo Roberto Federici
Abstract The morphometry of 432 glacial cirques in the Maritime Alps (Western French-Italian Alps), studied over several years of fieldwork, was analysed with the use of a geographical information system. Some of the parameters automatically evaluated from digital elevation models required an objective and relatively new definition. In particular, cirque length was measured along a line that, from the threshold midpoint, splits the cirque into two equivalent surfaces; cirque width was automatically drawn as the longest line inscribed in the cirque and perpendicular to the length line. Significant correlations were found among the different factors and parameters analysed. In particular, cirque shape analysis showed that cirques develop allometrically in the three dimensions, i.e. more in length and width than in altitudinal range. Nevertheless cirques of the Maritime Alps have a regular, almost circular shape (mean L/W value = 1.07). The correlations among length, width and area are all very high (r2= 0.8,0.9). In terms of size, cirques show a wide range in area from 0.06 to 5.2 km2 with a mean value of 0.4 km2. The largest cirques are found on SSW-facing slopes and at high elevations. Small cirques can be found at all altitudes but all those at high elevation are part of compound cirques at the main head valleys. Most cirques (37%) are characterized by a northern aspect; NE and SW are also frequent directions. [source]


Mergers between elliptical galaxies and the thickening of the Fundamental Plane

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2003
A. C. González-García
ABSTRACT We have carried out computer simulations to study the effect of merging on the Fundamental Plane (FP) relation. Initially, systems are spherical Jaffe models following a simple scaling relation (M/R2e= constant). They have been put on the FP by imposing different M/L values. Various orbital characteristics have been considered. Our results show that the merger remnants lie very close to the FP of the progenitors. Although non-homology is introduced by the merging process, mergers among homologous galaxies leave a pre-existing FP-relation intact. As a side result we find that variations in the point of view lead to non-negligible scatter about the FP. [source]


Exact analytical solutions to the Kratzer potential by the asymptotic iteration method

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2007
O. Bayrak
Abstract For any n and l values, we present a simple exact analytical solution of the radial Schrödinger equation for the Kratzer potential within the framework of the asymptotic iteration method (AIM). The exact bound-state energy eigenvalues (Enl) and corresponding eigenfunctions (Rnl) are calculated for various values of n and l quantum numbers for CO, NO, O2, and I2 diatomic molecules. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source]


Estimating Background and Threshold Nitrate Concentrations Using Probability Graphs

GROUND WATER, Issue 5 2006
S.V. Panno
Because of the ubiquitous nature of anthropogenic nitrate () in many parts of the world, determining background concentrations of in shallow ground water from natural sources is probably impossible in most environments. Present-day background must now include diffuse sources of such as disruption of soils and oxidation of organic matter, and atmospheric inputs from products of combustion and evaporation of ammonia from fertilizer and livestock waste. Anomalies can be defined as derived from nitrogen (N) inputs to the environment from anthropogenic activities, including synthetic fertilizers, livestock waste, and septic effluent. Cumulative probability graphs were used to identify threshold concentrations separating background and anomalous NO3 -N concentrations and to assist in the determination of sources of N contamination for 232 spring water samples and 200 well water samples from karst aquifers. Thresholds were 0.4, 2.5, and 6.7 mg/L for spring water samples, and 0.1, 2.1, and 17 mg/L for well water samples. The 0.4 and 0.1 mg/L values are assumed to represent thresholds for present-day precipitation. Thresholds at 2.5 and 2.1 mg/L are interpreted to represent present-day background concentrations of NO3 -N. The population of spring water samples with concentrations between 2.5 and 6.7 mg/L represents an amalgam of all sources of in the ground water basins that feed each spring; concentrations >6.7 mg/L were typically samples collected soon after springtime application of synthetic fertilizer. The 17 mg/L threshold (adjusted to 15 mg/L) for well water samples is interpreted as the level above which livestock wastes dominate the N sources. [source]