Water Glazing Research Articles

Effect of edible coating on the whole large yellow croaker (Pseudosciaena crocea) after a 3-day storage at −18 °C: With emphasis on the correlation between water status and classical quality indices

In order to find a suitable alternative for water glazing of frozen fish, the effect of coating (sodium alginate or chitosan) on the whole large yellow croaker (Pseudosciaena crocea) after a 3-day storage at −18 °C was compared. Besides the classical quality indices, such as color, texture properties and water-holding capacity, the change of water status and distribution of the sample were also examined by low field NMR (LF-NMR) and magnetic resonance imaging (MRI), and the correlation between water status and classical quality indices was investigated. The coating of sodium alginate (SA) presented lower cooking and drip loss, better texture and muscle color acceptability. The LF-NMR result also revealed that higher proportion of immobilized water trapped within the myofibrillar protein network was obtained after SA coating. This was also confirmed by the MRI result of more evenly distributed proton in the sample. Meanwhile, good correlations between LF-NMR results and drip loss, cooking loss, texture properties, as well as L* value were obtained. In conclusion, the coating of SA provided a promising approach to minimize the undesirable changes of frozen whole large yellow croaker. LF-NMR is a potential approach to rapidly assess the quality of frozen fish.

Investigating commercially relevant packaging solutions to improve storage stability of mechanically filleted Atlantic mackerel (Scomber scombrus) produced under industrial conditions

This study investigated the efficacy of three commercially relevant packaging methods (vacuum with water glazing VAC-G; vacuum with seawater VAC-S; shatter-layer packaging SL) to improve frozen storage stability of mechanically filleted Atlantic mackerel at − 25 °C, in comparison to water glazing alone (GL) and storage as whole unglazed, block frozen fish. Besides proximate composition and pH of raw material, quality changes were analysed by free fatty acid content (FFA), water holding capacity (WHC), cooking yield, lipid oxidation (lipid hydroperoxides, PV; non-protein bound thiobarbituric acid reactive substances, TBARS) and sensory profiles of cooked samples after 3.5, 8, 10 and 12 months of frozen storage. Vacuum-packaging was effective in mitigating the PV and TBARS as well as rancid odour and flavour. The inclusion of seawater in VAC-S altered the sensory textural attributes of the mackerel fillet to be more juicy, tender and soft and increased the attribute of salty flavour in the sample. SL delayed rancid odour and flavour by 2 months compared to GL. Processing of mackerel under industrial conditions, including filleting, handling, double-freezing and glazing accelerated the formation of FFA as well as losses of WHC and cooking yield in the fillet regardless the packaging methods.

Thermal performances of glazed energy storage systems with various storage materials: An experimental study

In the literature, two materials (such as water and phase change materials) have been studied frequently as potential heat energy storage medium in building applications. Many perspectives have been mentioned by researchers but there is too little information about significance of its application. In this experimental study, water and PCM glazing systems were tested simultaneously in natural environment using test chambers. Temperature histories were recorded in the corresponding chambers at interior glass surface for each sample. Time lag, temperature damping and average temperature for each glazing system were comparatively analyzed. It was observed that temperature variation at interior glass surface over a period of 48 h changes differently for each material. Compared to the traditional air filled glazing system, it was found that water glazing system has most promising temperature damping properties, but significantly unfavorable average temperature, while PCM glazing system has significantly promising average temperature and temperature dumping properties.

Efficiency Enhancement of a Dual-axis Solar PV Panel Tracker Using Water-Flow Double Glazing Technique

إنّ زاويةَ سقوط أشعةِ الشمس على سطحِ اللوح الشمسي ودرجة حرارته يُؤثّرانِ سلبياً على الطاقة الكهربائية للوح وكفاءته. أن مشكلة زاويةِ السقوط عادةً ما يتم حلها بإستخدام منظومة التتبع (المقتفي) الشمسي ذات المحورِين والذي يُبقي اللوح بشكل مستمر متعامد مع أشعةِ الشمس طِوال اليوم. هذا يُؤدّي إلى أقصى إمتصاصِ للإشعاعِ الشمسيِ والضروريِ لإنتاج الكميةِ القصوى مِن الطاقةِ وعند مستوىات عالية مِن الكفاءة الكهربائية. لحَلّ مشكلةَ الحرارة فقد تمّ استخدام تقنية الغرفة الزجاجية (المزججة) والتي يتدفقِ خلالها الماء بوصفها طريقة تبريد جديدةِ لتخفيض درجة حرارة اللوح. في هذه البحث، تمّ تصميم منظومِة التزجيج المقترحة بالتكامل مَع منظومة التتبع ثنائية المحاور واجريت التجارب المختبرية عليها لغرض تحسين كفاءةَ اللوح الشمسي، لاسيما في المناخِ الحارِ. نظام التزجيج المُقتَرَحِ يُمْكِنُ أَنْ يُؤدّي وظيفتين بشكل آني، أولاً، يعَمَل أداة تبريد لتقليل الحرارةِ المَخْزُونة في داخل اللوح أثناء عَملها وثانياً مرشِحا بصريا للطيفِ الضوئي. تمّ حساب معاملات التصميمُ الأمثل وبمستويات مختلفة لقيم نظامِ التزجيج وفقاّ لطريقةِ تاكوتشي. تمّ تنفيذ تجارب الإختبارِ في مدينةِ بغداد في العشرين والحادي والعشرين مِنْ يوليو/تموز 2016 على منظومة التتبع في حالتين مع إستعمال مقترح منظومة التزجيج وبدونها. تبُين النتائِج المستحصلة بأنّ، درجةَ الحرارة اللوح الشمسي بإستعمال منظومة التزجيج هَبطت بشكل ملحوظ بمقدار 44% وزادت كفاءتها الكهربائية بحاولي36.6 % عند بالمقارنة مع المنظومة التقليدية عند قيمة اشعاع شمسي 1213 W/m2.

Efficiency Enhancement of a Dual-axis Solar PV Panel Tracker Using Water-Flow Double Glazing Technique

The fall angle of sun rays on the surface of a photovoltaic PV panel and its temperature is negatively affecting the panel electrical energy produced and efficiency. The fall angle problem was commonly solved by using a dual-axis solar tracker that continually maintains the panel orthogonally positioning to the sun rays all day long. This leads to maximum absorption for solar radiation necessary to produce maximum amount of energy and maintain high level of electrical efficiency. To solve the PV panel temperature problem, a Water-Flow Double Glazing WFDG technique has been introduced as a new cooling tool to reduce the panel temperature. In this paper, an integration design of the water glazing system with a dual-axis tracker has been accomplished and experimentally tested in order to enhance the PV panel efficiency, especially at hot climates. The proposed glazing system can simultaneously perform two functions, firstly, working as a cooling tool for reducing the stored heat in the PV panel during its work and secondly as an optical filter for sun light spectrum. Optimum design factors with their levels for the glazing system were calculated according to Taguchi method. Test experiments were carried out in Baghdad city on the 20th and 21st July 2016 on the tracker with and without using the WFDG system. The obtained results show that, the PV panel temperature with using the WFDG system was significantly dropped by 44% and its efficiency increased maximally by 36.6% at solar irradiance of 1213W/m2 as compared with conventional one.

Efficiency Enhancement of a Dual-axis Solar PV Panel Tracker Using Water-Flow Double Glazing Technique

The fall angle of sun rays on the surface of a photovoltaic PV panel and its temperature is negatively affecting the panel electrical energy produced and efficiency. The fall angle problem was commonly solved by using a dual-axis solar tracker that continually maintains the panel orthogonally positioning to the sun rays all day long. This leads to maximum absorption for solar radiation necessary to produce maximum amount of energy and maintain high level of electrical efficiency. To solve the PV panel temperature problem, a Water-Flow Double Glazing WFDG technique has been introduced as a new cooling tool to reduce the panel temperature. In this paper, an integration design of the water glazing system with a dual-axis tracker has been accomplished and experimentally tested in order to enhance the PV panel efficiency, especially at hot climates. The proposed glazing system can simultaneously perform two functions, firstly, working as a cooling tool for reducing the stored heat in the PV panel during its work and secondly as an optical filter for sun light spectrum. Optimum design factors with their levels for the glazing system were calculated according to Taguchi method. Test experiments were carried out in Baghdad city on the 20th and 21st July 2016 on the tracker with and without using the WFDG system. The obtained results show that, the PV panel temperature with using the WFDG system was significantly dropped by 44% and its efficiency increased maximally by 36.6% at solar irradiance of 1213W/m2 as compared with conventional one.

The effect of glazing based on saponin-free quinoa (Chenopodium quinoa) extract on the lipid quality of frozen fatty fish

This study focussed on the rancidity stability of frozen fatty fish. Its basic objective was to investigate the effect of a glazing system including a saponin-free quinoa (Chenopodium quinoa) extract during the frozen storage of Atlantic mackerel (Scomber scombrus). For it, two different concentrations of 80% aq. (v/v) ethanol quinoa extracts (0.45 and 1.36 g lyophilised quinoa L−1 solution, respectively) were tested and compared with two control treatments (water glazing and non-glazing conditions). Chemical and sensory changes were monitored for a 8-month frozen storage. An inhibitory effect (p < 0.05) of the glazing system including the most concentrated saponin-free quinoa extract was observed on the lipid hydrolysis (free fatty acid formation) evolution and on the formation of secondary (thiobarbituric acid reactive substances) and tertiary (fluorescent compounds) lipid oxidation compounds. A sensory quality enhancement and shelf life increase was obtained in fish submitted to glazing conditions including the most concentrated quinoa extract in agreement to raw (gills and muscle odour) and cooked (muscle odour) descriptors. A novel quinoa-glazing system is proposed, this avoiding the inconveniences of the saponin compounds presence.

Effect of variables on the thickness of an edible coating applied on frozen fish – Establishment of the concept of safe dipping time

Glazing is a technique used to retard fish deterioration during storage. This work focuses on the study of distinct variables (fish temperature, coating temperature, dipping time) that affect the thickness of edible coatings (water glazing and 1.5% chitosan) applied on frozen fish. Samples of frozen Atlantic salmon (Salmo salar) at −15, −20, and −25 °C were either glazed with water at 0.5, 1.5 or 2.5 °C or coated with 1.5% chitosan solution at 2.5, 5 or 8 °C, by dipping during 10–60 s. For both water and chitosan coatings, lowering the salmon and coating solution temperatures resulted in an increase of coating thickness. At the same conditions, higher thickness values were obtained when using chitosan (max. thickness of 1.41 ± 0.05 mm) compared to water (max. thickness of 0.84 ± 0.03 mm). Freezing temperature and crystallization heat were found to be lower for 1.5% chitosan solution than for water, thus favoring phase change. Salmon temperature profiles allowed determining, for different dipping conditions, whether the salmon temperature was within food safety standards to prevent the growth of pathogenic microorganisms. The concept of safe dipping time is proposed to define how long a frozen product can be dipped into a solution without the temperature raising to a point where it can constitute a hazard.

Effects of glazing and chitosan-based coating application on frozen salmon preservation during six-month storage in industrial freezing chambers

Freezing and glazing are techniques commonly used to reduce the incidence of fish deterioration processes. In order to find an alternative to complement freezing and replace water glazing, the present work aimed at evaluating the effect of water glazing and edible coatings of 0.5% w/v and 1.5% w/v chitosan on quality parameters of frozen fish. Both types of coatings – water glazing and chitosan coatings – were applied directly on frozen Atlantic salmon (Salmo salar) and stored for 9 months at −22 °C. Several parameters such as coating/glazing loss, weight loss, drip loss, Total Viable Counts (TVC), Total Volatile Basic-Nitrogen (TVB-N), K-value, pH and color coordinates L*a*b* were periodically evaluated in order to compare glazing with the chitosan-based coatings and uncoated control samples. Samples coated with 1.5% w/v chitosan performed better in maintaining the color of the salmon and controlling microbial contamination of frozen and thawed samples.

Effect of chitosan-based solutions applied as edible coatings and water glazing on frozen salmon preservation – A pilot-scale study

The aim of this research was to compare the effect of chitosan solutions on frozen salmon preservation with that of water glazing. For this purpose, three chitosan solutions (0.25%, 0.50% and 0.75% w/v) and water were applied in different amounts (6%, 8% and 11% of coated fillet weight) directly on the surface of frozen salmon. In order to accelerate the deterioration processes, salmon was stored during 14weeks at −5°C. Microbial and chemical indices were used to assess deterioration during storage and the coating stability was evaluated through weight loss measurements. The results obtained showed that chitosan coatings can be a good barrier to protect frozen fish from deterioration. Microbial growth, assessed by total viable counts (TVC), and total volatile basic nitrogen (TVB-N) were maintained below the maximum limits recommended which are 5×105CFU/g and 35mg nitrogen/100g fish, respectively. The use of 0.50% and 0.75% chitosan solutions generally demonstrated to be more efficient in preventing salmon weight loss.

Whey protein-based coatings on frozen Atlantic salmon (Salmo salar): Influence of the plasticiser and the moment of coating on quality preservation

The effects of different whey protein concentrate coating formulations (with or without glycerol or sorbitol in two proportions) on frozen Atlantic salmon quality parameters were evaluated. The influence of the moment of coating application (before or after freezing) was also studied. The coating application after freezing increased the thaw yield, decreased the drip loss, and modified colour parameters of frozen and thawed fillets, in comparison with application before freezing. The moment of coating also influenced the colour of cooked fish fillets. The type of plasticiser affects the colour of thawed and cooked samples, but not the colour of frozen samples. The protein coatings delayed lipid oxidation of salmon fillets, providing better protection against it than water glazing, and this effect was more pronounced when glycerol instead of sorbitol was used in the coating formulation.WPC+glycerol (1:1) coating was the best for frozen Atlantic salmon protection. The sensory properties of salmon fillets were not modified by the use of this coating.