Water activity in liquid food systems : A molecular scale interpretation

Water activity has historically been and continues to be recognised as a key concept in the area of food science. Despite its ubiquitous utilisation, it still appears as though there is confusion concerning its molecular basis, even within simple, single component solutions. Here, by close examination of the well-known Norrish equation and subsequent application of a rigorous statistical theory, we are able to shed light on such an origin. Our findings highlight the importance of solute-solute interactions thus questioning traditional, empirically based “free water” and “water structure” hypotheses. Conversely, they support the theory of “solute hydration and clustering” which advocates the interplay of solute-solute and solute-water interactions but crucially, they do so in a manner which is free of any estimations and approximations

Degişik kaplama formülasyonlarının işlevinin kızartılmış tavuk parçalarına etkisi

The main objective of this study was to evaluate the functionality of batters containing various starch and gum types during deep-fat frying of chicken nuggets. Additionally, this study provided a correlation between batter consistency and quality attributes of deep fat fried chicken nuggets. In the first part, the batter viscosity was correlated with fried product quality. Additionally, time dependency of batters was determined under constant shear rate. Pregelatinized starch, hydroxypropyl methylcellulose gum and xanthan gum were determined to have the highest apparent viscosity. Batter viscosity was found to be correlated with coating pickup. All batters were found to have thixotropic behavior except guar gum added batter, which was found to behave like a rheopectic fluid.In the second part, to evaluate the effects of various starch and gum types on quality attributes of deep fat fried chicken nuggets, coating pickup, texture, moisture content, oil content, oil uptake ratio (Ur), bulk volume, porosity, cooking yield, and color were measured for frying times of 3, 6, 9 and 12 minutes at 180°C. Amylomaize, corn, waxymaize, pregelatinized starches, and guar, xanthan, gum arabic, HPMC, MC gums were used in batter formulations, individually. A batter formulation with no starch or gum addition was used as control. As a result of the study, among different starch types used, pregelatinized starch was found to provide a product with the lowest oil content, the highest moisture content, coating pick up and volume. When all the hydrocolloids were compared, HPMC gum was found to be the most effective one on improving quality attributes of deep-fat fried chicken nuggets in terms of moisture content, oil content and cooking yield.M.S. - Master of Scienc

Structural problems of energy economy and sample of nuclear energy

Enerji tarih boyunca insanoğlunun yaşamını sürdürebilmesi için bir zorunluluk, aynı zamanda sanayi devrimi ve artan makineleşmenin sonucunda, ülkelerin sürdürülebilir büyüme ve kalkınmayı sağlayabilmeleri için bir gereksinim olmuştur. Ülke ekonomilerinde arzulanan ekonomik istikrara sahip olunabilmesi, sürdürülebilir ekonomik büyüme ve kalkınmanın sağlanabilmesi için enerji stratejik önem arz eden bir sektör olma özelliği göstermektedir. Enerji kaynakları bakımından zengin olmayan ülkelerin gittikçe daha fazla dışa bağımlı hale gelmeleri ekonomi politikaları ile beraber kamu mali politikalarını da etkilemiş ve değiştirmiştir. Ekonomik büyümenin ve kalkınmanın sağlanabilmesi için gerekli üretim düzeyine ulaşmak, sürekli artan enerji talebini karşılayacak enerji arzını, güvenli, sürekli ve ucuz maliyetle sağlamakla mümkün olabilmektedir. Enerji arzında dışa bağımlılığı yüksek olan ülkelerin mali dengeleri üzerinde baskı yaratan enerji ithalat faturasının düşürülebilmesi, enerjinin yurtiçi kaynaklardan sağlanmasını gerektirmektedir. Enerji ithalatının yarattığı dış ödemeler, cari açığı tetiklemiş ve mali politikalar üzerinde baskı oluşturmuştur. Cari açığın finansmanı için enerji sektörüne geri dönüşü olmayan yüksek enerji vergileri uygulamaya konulmuş, bu da talebi inelastik olan enerjinin fiyatı üzerinde ağır bir yük oluşmasına neden olmuştur. Bu durum, vergi adaletine ters düşmektedir ve tersine artan oranlı bir vergi yapısı görünümünün ortaya çıkması sonucunu doğurmaktadır. Bu çalışmada, Dünya'da ve Türkiye'de bulunan enerji kaynakları ve uygulanan enerji politikalarına değinilmiş, enerjinin kamusal niteliği ve nükleer enerji konusunda Dünya'da uygulanan politikalar incelenmiş, Türkiye'nin enerjide dışa bağımlılığını azaltabilmesi ve vergi adaletine ters düşen enerji vergilerini düşürebilmesi için nükleer enerjinin gerekli olup olmadığı tartışılmış, enerji vergilerinin vergi adaletine ters düştüğü görüşünden hareketle vergi gelirlerinin ithalatın ve cari açığın finansmanı için kullanıldığı yapılan ekonometrik testlerle kanıtlanmaya çalışılmıştır. Anahtar Kavramlar: Enerjinin Kamusal Niteliği, Enerji Vergileri, Enerji Politikaları, Nükleer Enerji, Cari Açık, Bütçe AçığıEnergy has been a necessity for human beings to sustain their lives throughout the history and as a result of the industrial revolution and increased mechanization, it has become an obligation for the nations to provide sustainable growth and development. Energy is an important strategic sector to have a desired economic stability in countrys' economies and to provide sustainable economic growth and development. As the poorer countries in terms of energy resourches have become more foreign-dependant, it has affected and changed their public fiscal policies. In order to reach the necessary production limit to provide economic growth and development, the demand for the growing energy is to be met by providing safe, constant and cheap energy costs. Foreign payments caused by the energy imports triggered current deficit and made a pressure on fiscal policies. Higher energy taxes were put on energy sector for the current deficit and this led to a burden on energy prices in which the demand is inelastic. This situation is contrary to tax fairness and on the contrary it leads to a progressive income rate. International payments created by energy import triggered current deficit and caused presurre on financial policy.Higher energy taxes were put into practice in energy sector in order to meet the current deficit and this led to a heavy burden on energy cost which is inelastic. This is contrary to tax equity and reveals a progressive tax structure. In this study, the energy policies carried out in the World and in Turkey are mentioned, public quality of energy and the policies about nuclear energy carried out in the World are studied, whether nuclear energy is necessary or not for Turkey in order to decrease the foreign dependancy of energy and the energy taxes which are contrary to tax fairness are discussed, with the opinion of energy taxes to be contraray to tax fairness, it is tried to be proved that tax income is used for import and current deficit by means of econometric tests. Keywords: Public Nature of Energy, Energy Taxes, Energy Policies, Nuclear Energy, Current Deficit, Budget Defici

FOOD PRESERVATION BY PULSED ELECTRIC FIELDS AND SELECTED ANTIMICROBIALS By

The members of the Committee appointed to examine the dissertation o

Effects of batters containing different gum types on the quality of deep-fat fried chicken nuggets

The effects of various gum types [hydroxypropylmethylcellulose (HPMC), guar gum, xanthan gum, gum arabic] on the quality of deep-fat fried chicken nuggets were studied. Chicken samples, 0.04 m in diameter and 0.015 m in thickness taken from the breast portion, were coated with batters composed of a 3:5 solid to water ratio by immersion. The solid content of batter formulations contained equal amounts of corn and wheat flours, 1.0% gum, 1.0% salt and 0.5% leavening agent. As control, batter without gum addition was used. Samples were fried at 180 degrees C for 3, 6, 9 and 12 min. The hardness and oil content of the chicken nuggets increased whereas the moisture content decreased during frying. HPMC and xanthan gums reduced oil absorption significantly compared with other gums and the control. When gum arabic was added to the batter formulation, a product with the highest oil content and porosity was obtained. (c) 2005 Society of Chemical Industry

Effects of hydrocolloids on apparent viscosity of batters and quality of chicken nuggets

The effect of different types of starches and gums on batter consistency and the effect of batter consistency on quality parameters of deep-fat fried chicken nuggets were determined in this study. Consistency of batter was correlated with coating pickup and oil content of the product. Addition of different starch and gum species to batter was found to be effective for both viscosity development and quality attributes of deep-fat fried chicken nuggets. Hydroxypropyl methylcellulose gum (HPMC), xanthan gum, and pregelatinized starch provided the highest consistency to the batters. Amylomaize starch addition to the batter formulation provided about 50% increase in texture of nuggets as compared to the control. Chicken nuggets coated with batters containing HPMC, xanthan, or guar gum had the lowest oil content. HPMC reduced oil content by about 54%, while the reduction in oil content was 40% and 33% in the case of xanthan and guar gum addition, respectively

Functionality of batters containing different starch types for deep-fat frying of chicken nuggets

The effect of various starch types (amylomaize, corn, waxymaize, pregelatinized tapioca) on quality attributes (texture, moisture content, oil content, color, coating pick up, cooking yield, volume and porosity) of deep-fat fried chicken nuggets were studied. Chicken samples, 0.04 m in diameter and 0.015 m in thickness, taken from the breast portion, were coated with batters composed of a 3:5 solid to water ratio by immersion. The solid content of batter formulations contained equal amounts of corn and wheat flour, 5.0% starch, 1.0% salt and 0.5% leavening agent. As control, batter without starch addition, was used. Samples were fried at 180degreesC for 3, 6, 9 and 12 minutes. Crispness and oil content of chicken nuggets increased, whereas moisture content decreased with increasing frying time. Starch addition to the formulations increased crispness of the product significantly at the last stages of frying. The highest porosity and oil content was obtained when corn starch was used. Pregelatinized tapioca starch was found to provide a product with the lowest oil content, the highest moisture content, coating pick up and volume

Characterisation of deep-fried batter and breaded coatings

Deep-fried battered and breaded coatings provide foods with texture, flavour, reduced moisture loss and oil uptake. The physical characteristics of deep-fried batter and breadcrumb coatings was investigated for deep-fried prawns. Previous data on the effect of breadcrumb size on the microstructure of the coating is limited, therefore breadcrumbs were divided using the following sieve sizes and then applied to the coating in order to investigate the effect of breadcrumb size on the physical and mechanical properties: 4.0 mm, 2.8 mm, 2.0 mm, 1.4 mm, 1.0 mm, 710 μm, 500 μm, 355 μm. After frying, internal morphology was studied using X-ray microCT showing that the total porosity of coatings decreases with breadcrumb size whilst pore size distribution and structure thickness distribution increased with breadcrumb size. As crispness is a fundamental sensorial property of deep-fried battered products, crispness was evaluated by uniaxial compression to acquire mechanical and acoustical measurements simultaneously. Results showed decreasing breadcrumb size reduced the number of multiple failures, reduced jagged appearance of the force profile was observed, reduced maximum compression force and acoustic emission, which has been used as a representative of crispness. This study provides evidence of the importance of breadcrumb size in deep-fried battered and breaded formulations.</p