Life Sciences Commons^™

Melamine Contamination Of Infant Formula In China: The Causes, Food Safety Issues And Public Health Implications, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

Reflections On Recycling, Pollution And History Or, How To Beat The High Cost Of Living, Richard B. Philp

Richard B. Philp

Lessons learned during the Great Depression and World War II may have to be relearned. The three Rs (reduce, reuse and recycle) were essential then to individual and national survival. A fourth R, repair, was practised as well. These lessons, if relearned, will stand us in good stead when dealing with the current economic climate as well as with problems of pollution and global warming.

Modelling Tempering Behaviour Of Dark Chocolates From Varying Particle Size Distribution And Fat Content Using Response Surface Methodology, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Central Composite Rotatable Design (CCRD) for K=2 was used to study the combined effects of multi-stage heat exchangers for Stages 1 (14–30 °C) and 2 (12–28 °C) coolant temperatures at constant Stage 3 coolant and holding temperatures during tempering of dark chocolates using laboratory-scale mini-temperer. Quantitative data on chocolate temper index (slope) were obtained for products with varying particle size distribution (PSD) (D90 of 18, 25, 35 and 50 μm) and fat (30% and 35%) content. Regression models generated using stepwise regression analyses were used to plot response surface curves, to study the tempering behaviour of products. The results showed …

Flavor Formation And Character In Cocoa And Chocolate: A Critical Review, Emmanuel Ohene Afoakwa, Alistaiar Paterson, Mark Fowler, Angela Ryan

Professor Emmanuel Ohene Afoakwa

Chocolate characters not only originate in flavor precursors present in cocoa beans, but are generated during post-harvest treatments and transformed into desirable odor notes in the manufacturing processes. Complex biochemical modifications of bean constituents are further altered by thermal reactions in roasting and conching and in alkalization. However the extent to which the inherent bean constituents from the cocoa genotype, environmental factors, post-harvest treatment and processing technologies influence chocolate flavor formation and relationships with final flavor quality, has not been clear. With increasing speciality niche products in chocolate confectionery, greater understanding of factors contributing to variations in flavor character would …

Characterization Of Melting Properties In Dark Chocolates From Varying Particle Size Distribution And Composition Using Differential Scanning Calorimetry, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Melting properties in dark chocolates processed from varying particle size distribution (PSD), fat and lecithin content were studied using differential scanning calorimetry (DSC). Compositional parameters were PSD (D90 (90% finer than this size) of 18, 25, 35 and 50 lm), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Variations in PSD had no influence on crystallinity of products. Fat and lecithin content influenced the degree of crystallinity and melting properties (Tend, Tindex and DHmelt) of the products. Increasing fat content caused consistent increases in degree of crystallinity and crystal size distribution, thus effecting significant changes in Tend, …

School Feeding Programmes In Africa - A Case Study, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

Effects Of Tempering And Fat Crystallisation Behaviours On Microstructure, Mechanical Properties And Appearance In Dark Chocolates, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

Factors Influencing Quality Charateristics Of Chocolate Systems During Industrial Manufacture, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

Improving Productivity In Mixed-Species Plantations, Mila Bristow, J Doland Nichols, Jerome K. Vanclay

Professor Jerome K Vanclay

Mixed species plantations are often promoted as being environmentally preferable to monocultures, but are rarely considered operationally viable by commercial forest growers. Despite many publications documenting benefits demonstrated in research studies (e.g., Kelty 2006; Forrester et al. 2006b; Wood and Vanclay 1995), and despite continuing calls from a wide range of advocates for mixed-species plantations, polyculture remains the exception rather than the rule in industrial plantation forestry (Nichols et al 2006)...

Effects Of Tempering And Fat Crystalization Behaviours On Microstructure, Mechanical Properties And Appearance In Dark Chocolate Systems., Emmanuel Ohene Afoakwa, Alistaiar Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Fat crystallisation behaviours in dark chocolates from varying particle size distribution (PSD) (D90 of 18, 25, 35 and 50 µm) was studied, yielding products from different temper regimes (optimal temper, over-temper and under-temper), and their effects on mechanical properties and appearance evaluated. Microstructures of derived products were determined using stereoscopic binocular microscopy. Wide variations in mechanical properties and appearance were noted in products from different particle size and temper regimes. Particle size (PS) was inversely related with texture and colour, with the greatest effects noted in hardness, stickiness and lightness at all temper regimes. Over-tempering caused significant increases in product …

Extraction Of Lipids From Buttermilk Using Supercritical Carbon Dioxide, Harit K. Vyas, Johanna C. Astaire, Rafael Jiménez-Flores

Rafael Jiménez-Flores

Abstract of paper presented at the 2002 Joint Annual Meeting of the American Dairy Science Association & the American Society of Animal Science.

Disulfide Bonding Patterns Between Β-Lactoglobulin And Κ-Casein In A Heated And Spray-Dried Milk-Model, Annie Bienvenue, C. S. Norris, Michael J. Boland, Lawrence K. Creamer, Rafael Jiménez-Flores

Rafael Jiménez-Flores

Abstract of paper presented at the 2002 Joint Annual Meeting of the American Dairy Science Association & the American Society of Animal Science.

Writing Research Proposal: Literature Review And Database Search, Mamoudou H. Dicko Prof.

Pr. Mamoudou H. DICKO, PhD

Iron Fertilization Of Kentucky Bluegrass, David Wehner, Jean Haley

David J. Wehner

Iron applications are sometimes used to enhance the color (darker green) of turfgrass stands even when iron is not deficient. A study was conducted to determine the feasibility of replacing a portion of the total yearly N applied to Kentucky bluegrass (Poa pratensis L.) with iron. Turfgrass response to iron chelate (Sequestrene 330) applications at 2.2 kg Fe ha^-1 in combination with three liquid-applied N sources (urea, Formolene, and FLUF) at 25 kg N ha^-1 was compared to turf response from applications of the N sources at 49 kg N ha^-1. Iron was substituted for …

Building Sustainable Agricultural Development Through Home-Grown School Feeding - The African Approach, Emmanuel Ohene Afoakwa, Linley Chiwona-Karltun

Professor Emmanuel Ohene Afoakwa

Proper nutrition is critical for optimal growth, cognitive development, general well-being and academic performance of children. Access to good nutrition either at home or through the educational system can contribute to the elimination of malnutrition and its associated health and developmental problems. In this regard, The 2005 UN World Summit recommended the expansion of local school feeding programmes, using home-grown foods where possible as one of the “Quick impact initiatives” to achieve the Millennium Development Goals, especially for rural areas facing the dual challenge of high chronic malnutrition and low agricultural productivity.

A Microecosystem For Fertilizer And Pesticide Fate Research, B. E. Branham, David J. Wehner, W. A. Torello, A. J. Turgeon

David J. Wehner

A microecosystem was designed to study the behavior of pesticides, fertilizers, or related compounds applied to plant stands. The system consists of three parts: a brass base that holds the plant growth media, a glass atmospheric chamber that rests on the base, and a set of analytical traps. The brass base is fitted with a porous ceramic plate so that tension can be applied to the water in the growing media. Air enters the bottom of the glass atmospheric chamber and exits through the top into appropriate trapping systems to recover volatilized pesticides, ammonia, or metabolized 14CO2 from labeled compounds. …

The Fate Of Diazinon Applied To Thatched Turf, B. E. Branham, David J. Wehner

David J. Wehner

Diazinon (0,0-diethyl-0-(2-isopropyl-6-methyl-4-primidinyl) phosphorothioate) is widely used to control turfgrass insect pests. Poor control of soil-inhabiting insects has been found where diazinon has been applied to thatched turfgrass stands. The purpose of this study was to evaluate the environmental fate of diazinon applied to turfgrass stands. A microecosystem was used to follow the fate of radiolabeled diazinon surface applied to Kentucky bluegrass (Poa pratensis L.) turfs, with or without a thatch layer, growing on Flanigan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) irrigated daily or every 4 days. Loss of diazinon by volatilization, leaching, and degradation accompanied by release of …

Heat Tolerance Screening Of Field-Grown Cultivars Of Kentucky Bluegrass And Perennial Ryegrass, D. D. Minner, P. H. Dernoeden, David J. Wehner, M. S. Mcintosh

David J. Wehner

The quality of cool-season turfgrasses frequently declines during periods of high temperature stress. Simple tests are needed to rapidly identify heat tolerant germplasm for incorporation into breeding programs. Facilitative screening tests have been devised, however, in the few studies that have been performed only immature and greenhouse or growth chamber-grown plants have been evaluated. To be of practical value, results of screening tests, employing plants grown under artificial conditions, should correlate closely with results of tests involving field grown plants. The objective of this research was to evaluate the heat tolerance of several cultivars of Kentucky bluegrass (Poa pratensis L.) …

Urease Activity In A Kentucky Bluegrass Turf, W. A. Torello, David J. Wehner

David J. Wehner

The components of a turfgrass ecosystem, including plants, an intervening layer of thatch and the underlying soil, influence the fate of topically applied urea fertilizer. The loss of urea N by ammonia volatilization may be governed by the rate of urea hydrolysis. The main objective of this study was to determine the extent of urease activity associated with turfgrass plant tissue, thatch, and the underlying soil. This information may help elucidate the mechanism of ammonia loss following urea application. Because a turfgrass stand frequently possesses an extensive thatch layer that may serve as the primary plant growth medium, additional objectives …

Heat Tolerance Of Kentucky Bluegrasses, Perennial Ryegrasses, And Annual Bluegrass, David J. Wehner, T. L. Watschke

David J. Wehner

Use of cool-season turfgrasses in transitional environments is limited, in part, by their heat tolerance. Development of a rapid heat tolerance screening technique would be of value in determining the potential of turf•grasses for use in warmer areas. The heat tolerance of 22 Kentucky bluegrass (Poa pratensis L.) cultivars, Poa annua L., and four perennial ryegrass cultivars (Lolium perenne L.) was evaluated by exposing plants for 30 min to temperatures ranging from 41 to 49 C in single degree intervals. Ten-week-old plants, which had been grown under a low level of N fertilization and watered infrequently to maximize heat tolerance …

Heat Tolerance Of Kentucky Bluegrasses, Perennial Ryegrasses, And Annual Bluegrass, David J. Wehner, T. L. Watschke

David J. Wehner

Use of cool-season turfgrasses in transitional environments is limited, in part, by their heat tolerance. Development of a rapid heat tolerance screening technique would be of value in determining the potential of turf•grasses for use in warmer areas. The heat tolerance of 22 Kentucky bluegrass (Poa pratensis L.) cultivars, Poa annua L., and four perennial ryegrass cultivars (Lolium perenne L.) was evaluated by exposing plants for 30 min to temperatures ranging from 41 to 49 C in single degree intervals. Ten-week-old plants, which had been grown under a low level of N fertilization and watered infrequently to maximize heat tolerance …

Effect Of P, K, And Lime On Growth, Composition, And P Absorption By Merion Kentucky Bluegrass, T. L. Watschke, D. V. Waddington, David J. Wehner, C. L. Forth

David J. Wehner

Information is needed concerning the effects of different soil fertility levels on the activity of turfgrass roots in that part of the soil profile sampled for routine soil tests. In Pennsylvania, a sampling depth of 5 to 7.5 cm is suggested for established turf. A study was conducted on 'Merion' Kentucky bluegrass (Poa pratensis L.) to determine relationships among lime, phosphorus, and potassium applications; soil test results; foliar growth and elemental analysis; and root activity as determined by 32P uptake from three soil depths. In the field, soil pH values were 5.8 and 7.0, P ranged from 13 to 137 …

Models For Predicting The Lower Limit Of The Canopy-Air Temperature Difference Of Two Cool Season Grasses, Dennis Martin, David Wehner, C. Throssell

David J. Wehner

Estimation of the lower limit of the canopy-air temperature differential, (T_c–T_a)_LL, is required for calculation of an empirically-based crop water stress, index. This research determined the complexity of model needed for accurate estimation of (T_c–T_a)_LL for several field grown cultivars of Kentucky bluegrass (Poa pratensis L.) and for creeping bentgrass (Agrostis stolonifera L. var. palustris (Huds.) Farw.). Regression models using vapor pressure deficit of the air (VPD), net radiation load (R_n), and wind speed (WS) were developed for predicting (T_c–T_{a …}

Melamine/Urea And Oxamide Fertilization Of Kentucky Bluegrass, David Wehner, Dennis Martin

David J. Wehner

The commercial lawn care industry represents a large market for N sources. A formulated melamine (2,4,6-triamino-s-triazine) plus urea combination (MLU) (45% melamine by weight) and oxamide were evaluated for use by the lawn care industry by comparing turfgrass response from these fertilizers to that from urea, sulfur coated urea (SCU), ureaformaldehyde (Nitroform), and a non-fertilized check. Fertilizers were applied four times per year to field plots of Kentucky bluegrass (Poa pratensis L.) growing on a Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) at a rate of 49 kg N ha-1 per application. Color ratings and clipping weights were determined …

Relationship Between Rheological, Textural And Melting Properties Of Dark Chocolate As Infuenced By Particle Size Distribution And Composition, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

In dark chocolate, rheological properties during processing are influenced by particle size distribution (PSD), fat and lecithin contents with consequential effects on finished texture and melting characteristics. Multivariate regression, correlation and principal component analyses (PCA) were used to explore their interrelationships. A 4 x 3 x 2 factorial experiment was conducted with varying PSD [D90 (90% finer than this size) of 18ìm, 25ìm, 35ìm and 50ìm), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%). Rheological properties (yield stress and apparent viscosity), textural properties (firmness, index of viscosity and hardness) and melting index (duration) were respectively measured using shear …

Particle Size Distribution And Compositional Effects On Textural Properties And Appearance Of Dark Chocolates, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Particle size distribution (PSD) and composition in dark chocolate were varied and their effects on textural properties of molten and tempered chocolates determined using a TA.HD Plus Texture Analyzer. Surface colour was evaluated in terms of CIELAB parameters L*, C* and h° using a HunterLab Miniscan Colorimeter. Compositional parameters for particle size distribution were [D90 (>90% finer) of 18 ìm, 25 ìm, 35 ìm and 50 ìm], fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Results showed that PSD, fat and lecithin content significantly (p<0.05) influenced the textural parameters with significant interactions among factors. Particle size was inversely correlated with firmness (1235 - 173 g), consistency (50410 - 7029 g.s), cohesiveness (1594 - 262 g), index of viscosity (5737 - 1099 g.s) and hardness (7062 - 5546 g) with chocolates containing 25% fat and 0.3% lecithin. With higher fat and lecithin contents, PSD influence was reduced. PSD and fat concentration inversely influenced all colour measurements (L*, C* and h°) of samples. High correlations (r = 0.71 – 1.00, P<0.001) were observed between texture parameters and colour. It was concluded that PSD, fat and lecithin contents and their interactions were central to changes in textural properties and appearance during processing of dark chocolates.