Academic literature on the topic 'Okra – Drying'

Okra [Abelmoschuscaillei (A. Chev.) Stevels] drying was studied by a factorial experiment under randomized complete block design using a laboratory-scale hot-air dryer. Two osmotic solution concentrations (40 and 60 oBrix of sucrose), three osmotic process durations (60, 120 and 180 min) and four drying temperatures (50, 60, 70 and 80 oC) were considered with each trial conducted in triplicates. Drying rate was determined as the ratio of change in mass of okra to the change in drying time as drying progresses. The ash content, crude fibre, crude fat, crude protein, bulk density, least gelation concentration and water absorption capacity were investigated as quality parameters. Model equations were developed using Essential Regression (ESSREG) analysis and Statistical Package for Social Sciences (SPSS) to relate output parameters to process variables. The results showed that an optimum drying rate of 16.69 g/h could be achieved by subjecting okra to osmotic dehydration pretreatment using a solution of 40 oBrix sucrose for 149.10 min and dried with a temperature of 80 oC. The ash content of 3.76% could be obtained at 40 oBrix, 180 min and 50 oC. An optimum value of 29.65% was obtained for crude fibre at an osmotic solution concentration of 60 °Brix, osmotic process duration of 180 min and drying temperature of 80 oC. Crude fat content of okra has 4.03% as its optimum value and this corresponds to a combination of 60 oBrix osmotic solution concentration, 180 min osmotic process duration and 74.60 oC drying temperature. An osmotic solution concentration of 60 °Brix, osmotic process duration of 60 min and drying temperature of 80 oC should be selected to give the optimum crude protein of 14.12%. Predicted values of drying rate, ash content, crude fibre, crude fat, crude protein and water absorption capacity (WAC) compared favourably with the observed values. This implies the models reliably predicted the drying characteristics of okra very well in terms of these output parameters. It could be inferred from this study that the drying process of okra can be optimized under different drying conditions. Further studies should be carried out on the factors that affect the storability of dried okra for long-time storage and preservation. An investigation into the use of sodium chloride for osmotic dehydration pretreatment as a means of improving the post-drying palatability of okra should be considered for further study.

Penelitian ini bertujuan untuk mengetahui aktivitas antioksidan saat sebelum dan setelah pengeringan buah Okra. Analisis fisik meliputi analisis warna dan PSD (Particle Size Distribution). Analisis kimia meliputi uji pH, conductivity dan TDS (Total Disolve Solid). Uji aktivitas antioksidan dilakukan dengan metode DPPH. Analisis data warna menggunakan uji korelasi. Data PSD, uji pH, konduktivitas, TDS, dan aktivitas antioksidan disajikan secara deskriptif. Hasil penelitian menunjukkan bahwa pengeringan buah Okra menjadi tepung Okra, tidak merusak aktivitas antioksidan. Proses pengeringan tepung Okra meningkatkan derajat kecerahan Okra dengan hasil uji statistik nilai L* <0,0001 dan a* 0,0002 (p<0,05). Distribusi ukuran partikel tepung Okra lebih kecil sehingga mudah larut dalam air. Buah Okra memiliki pH yang lebih asam yang mengakibatkan konduktivitasnya menjadi lebih tinggi sehingga padatan yang terlarut (kation, anion, mineral) juga semakin tinggi. Kesimpulannya, aktivitas antioksidan tepung buah Okra dapat diidentifikasi baik sebelum maupun setelah pengeringan dan proses pengeringan dapat berhasil memelihara aktivitas antioksidannya.This study aims to determine the physical, chemical, and antioxidant activities before and after drying the Okra fruit. Color analysis and PSD (Particle Size Distribution) were measured for physical analysis. pH test, conductivity, and TDS (Total Disolve Solid) was also measured as chemical analysis. Antioxidant activity was tested using DPPH. Color data was analyzed using correlation test. PSD data, pH test, conductivity, TDS, and antioxidant activity were presented descriptively. The results showed that drying Okra fruit to produce Okra flour did not damage antioxidant activity. The drying process of Okra flour brightening the color of the Okra fruit and in accordance with the statistical test that was resulted value of L* <0.0001 and a* 0,0002 (p <0.05). The particle size distribution of Okra flour was categorized as small. A much more acidic pH and higher in conductivity were found in the fresh Okra. As conclusion, antioxidant activity of Okra flour could be determined and the drying may be applied since able to maintain antioxidant activity in Okra flour.

In this study, sun drying behaviours of green bean and okra were investigated. Drying experiments were conducted in Iskenderun-Hatay, Turkey. The drying study showed that the times taken for drying of green bean and okra from the initial moisture contents of 89.5% and 88.7% (w.b.) to final moisture content of around 15?0.5% (w.b.) were 60 and 100 h in open sun drying, respectively. The constant rate period is absent in drying curves. The drying process took place in the falling rate period. The drying data were fitted to thirteen thin-layer drying models. The performance of these models was investigated by comparing the determination of coefficient (R2), reduced chi-square (c2) and root mean square error (RMSE) between the observed and predicted moisture ratios. Estimations by Approximation of diffusion (for green bean) and Midilli et al. models (for okra) were in good agreement with the experimental data obtained.

The purpose of this paper is to investigate the impact of vacuum microwave drying on the quality of okra. The curves of colour, fracture resistance, rehydration ratio and the content of vitaminC were obtained at various drying times, vacuum degrees and microwave powers. Results showed that an increase in drying time and microwave power resulted in serious colour change when compare the dry product to fresh okra. However, the higher the vacuum, the slighter the colour changed. The fracture resistance decreased and the brittleness was good when drying time was increased to high level of 14min and 16min. Increasing vacuum degree also made fracture resistance decreased; rehydration ratio increased with the time and microwave power increased, but decreased if the time exceeds 14min. The rehydration ratio of okra is also affected by the vacuum degree, increasing which led the rehydration ratio increased significantly at the beginning of drying and then slowly; the greater the drying time and microwave power, the more lost of vitaminC, however, higher vacuum degree was found to be beneficial to save the vitaminC.

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CNPq
O quiabo é um vegetal presente o ano inteiro sendo bastante consumido em diversas partes do mundo. Contudo apresenta tempo de prateleira curto gerando perdas pós-colheita. Assim a secagem constitui uma alternativa para minimizar o desperdício. Dentro dessa linha o presente trabalho tem como objetivo avaliar o efeito da secagem em temperaturas distintas sobre o teor de compostos fenólicos, atividade antioxidante e características físico-químicas do quiabo. Foi usado o secador de leito fixo com as temperaturas de 43ºC e 65ºC e uma velocidade do ar de 0,85 m/s. Todas as análises feitas no quiabo in natura foram realizadas no quiabo desidratado. Os resultados obtidos mostraram que houve uma concentração de todos os nutrientes avaliados após o processo de secagem. A aplicação de modelos empíricos resultou que o modelo de Page foi o mais adequado (R2=99,95%, SSE= 0,002 e RMSE= 0,0007) para a temperatura de 43ºC e para a temperatura de 65ºC o modelo Logarítmico forneceu melhor ajuste (R2=99,6%, SSE=0,008 e RMSE=0,020). A aplicação do modelo fenomenológico forneceu um valor de Deff = 9,16x10-8 m2/s (R2=98,5%) para a temperatura de 43ºC e um Deff = 2,16x10-7 m2/s (R2=98,2%) para 65ºC.
The okra is a vegetable present the whole year being quite consumed in several parts of the world. However, it presents short shelf life generating post-harvest losses. Thus drying is an alternative to minimize waste. Within this line the objective of this work is to evaluate the effect of drying at different temperatures on the content of phenolic compounds, antioxidant activity and physical and chemical characteristics of okra. The fixed bed drier was used with temperatures of 43ºC and 65°C and an air velocity of 0.85 m/s. All the analyzes made on okra in natura were carried out on dehydrated okra. The results showed that there was a concentration of all nutrients evaluated after the drying process. The application of empirical models showed that the Page model was the most adequate (R2 = 99.95%, SSE = 0.002 and RMSE = 0.0007) for the temperature of 43 ° C and for the temperature of 65 ° C the logarithmic model provided the best fit (R2 = 99.6%, SSE = 0.008 and RMSE = 0.020). The application of the phenomenological model yielded a Deff = 9.16x10-8 m2 / s (R2 = 98.5%) for the temperature of 43ºC and a Deff = 2,16x10-7 m2 / s (R2 = 98.2 %) to 65 ° C.

Orientadores: Sandra Cristina dos Santos Rocha, Antonio Marsaioli Junior
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: O aproveitamento de resíduos industriais tem se tornado muito importante para evitar contaminação do meio e reaproveitar recursos até então considerados desperdícios ou perdas nas indústrias químicas e de alimentos. Na atualidade não se tem um valor aproximado da produção de leite de soja no mundo, mas sabe-se que grandes quantidades de resíduo são geradas pela produção do leite de soja, resíduo este que na literatura se denomina "Okara". Uma forma de aproveitar este resíduo é através de uma operação de secagem. A secagem é uma tecnologia amplamente utilizada pelas indústrias para manter a qualidade e prolongar a vida de prateleira dos produtos devido à diminuição das reações degradativas. Outro resultado da secagem é a diminuição do tamanho e peso do produto, facilitando assim seu transporte e armazenamento. No entanto, ainda hoje, apesar dos avanços tecnológicos nas indústrias químicas e de alimentos, persistem problemas quanto aos métodos específicos adequados para a secagem dos diferentes materiais biológicos, especialmente aqueles usados para alimentação humana. O resíduo de leite de soja é rico em proteínas, fibras e vitaminas, o que o torna de grande importância para diminuir o grande déficit de proteína que tem a população mundial, além de ser possível elaborar novos produtos utilizando o Okara seco como ingrediente e desta forma dar valor agregado aos novos produtos. O Okara apresenta-se como um material particulado muito úmido 80% (b.u.), e com alto teor de umidade superficial. A realização de uma operação mecânica de prensagem anterior à operação de secagem é necessária, para reduzir o teor de umidade até cerca de 60% (b.u.), otimizando dessa maneira a secagem, sem gastos não necessários de energia. O Okara é um material termo-sensível e, enquanto úmido, altamente deteriorável. Após o processo de prensagem, este material é particulado, altamente coesivo, de difícil escoamento, poroso e com alto teor de umidade interna (não podendo ser caracterizado como uma pasta). O objetivo desta pesquisa é estudar a secagem do resíduo do leite de soja, Okara, utilizando três tipos de secadores: secador de leito de jorro, secador de cilindro rotativo com aplicação de microondas e secador de forno de microondas. A secagem no leito de jorro foi realizada em batelada, enquanto, no secador de cilindro rotativo com aplicação de microondas, foi realizada em forma contínua. Foi necessária a utilização de material inerte nestes dois secadores: no secador de leito de jorro o inerte que apresentou melhor fluidodinâmica junto com o Okara úmido foi o polipropileno; diferente do secador rotativo, onde o inerte que apresentou melhor acompanhamento no transporte do Okara. dentro do cilindro foi o poliestireno. O processo de elaboração do Okara foi o mesmo para os dois equipamentos. As variáveis de processo analisadas no secador de leito de jorro foram: temperatura do ar de secagem, razão entre a vazão do ar e a vazão de jorro mínimo e tempo de trituração do material; no secador rotativo com aplicação de microondas as variáveis independentes analisadas foram: temperatura e vazão do ar de secagem e potência das microondas. Para os dois secadores foi elaborado um planejamento fatorial 2³, tendo como respostas avaliadas: teor de umidade para um determinado tempo de secagem e constantes do modelo de Page para a cinética de secagem (esta última apenas para o secador de leito de jorro). Foi ainda avaliado o desempenho operacional de ambos secadores, através da produtividade e eficiência térmica do processo. Foram também determinadas as propriedades físicas para o material antes e à saída nos secadores. O secador de forno de microondas foi utilizado para determinar as curvas de secagem, controlando-se as mesmas variáveis independentes analisadas no secador de cilindro rotativo.
Abstract: The use of industrial residues has become more and more important to avoid the environment contamination and to make use of resources considered wastes in the chemical and food industries. Actually, the approximated soy milk production in the world is unknown; however, it is known that large amounts of its residue, named "Okara", are generated by its production. Drying is an operation that could make this residue viable. The drying is a technology widely used by the industries to improve the quality and extend the shelf-life of the products due the decrease of the degraded reactions. Another result of a drying process is the decrease of the product's weigh and size, facilitating its transport and storage. However, until now, despite the technologic overhauls in the chemical and food industries, problems persist on defining the specific appropriate methods to dry different biological materials, mainly those used as human food. The soy milk residue is rich in proteins, fibers and vitamins, what makes it important in decreasing the enormous protein deficit of the world population, beyond the possibility of elaborating new products using Okara as ingredient, thus giving aggregate value to these new products. Okara is a very moist particulate material, 80% (b.u.), with high content of superficial moisture. A mechanic pressing operation before drying is indicated to decrease the Okara initial moisture content to around 60% (b.u.) and in this way optimize the drying process, without non-necessaries energy losses. The Okara is a thermo-sensible material and, while wet, highly deteriorative. After pressing, this material is particulate, highly cohesive, hard flowing, porous and with highly internal moist content (being not possible to be characterized as a paste). The objective of this research is the analysis of the soy milk residue drying using three types of dryers: conventional spouted bed dryer, rotary cylindrical dryer assisted by microwaves and microwave oven drier. The drying in the spouted bed was made in batch process while, in the rotary cylindrical dryer with application of microwaves it was conducted continuously. The use of inert material inside the dryer was necessary in both cases: in the spouted bed dryer, the inert that showed better fluid-dynamic with the Okara was the polypropylene, while in the rotary dryer the inert that showed better transport monitoring of Okara particles was the polystyrene. The same procedure was followed to prepare the Okara for both equipments. The variables analyzed in the spouted bed dryer were: drying air temperature, ratio between the air flow rate and minimum spout flow rate and time of material shredding; in the rotary cylindrical dryer assisted by microwaves, the independent variables were: drying air temperature and flow rate and microwave power. For both dryers, an experimental factorial design, 2³, was applied and the responses analyzed were: Okara moisture content for a fixed drying time and parameters of Page model for the drying kinetics (the last for the spouted bed dryer only). Operational performance was also determined for both dryers by productivity and process thermal efficiency. Physical properties were determined for Okara before drying and after the dryer exit. The microwave oven dryer was used to determine the drying kinetics, controlling the same variables as in the rotary cylindrical dryer.
Doutorado
Engenharia de Processos
Doutor em Engenharia Química

碩士
國立勤益科技大學
冷凍空調系
106
Human body has an organ which is called pancreas. One function of pancreas is to secrete insulin to reduce blood sugar. When the pancreas fails to control the blood sugar within normal range, the diabetes is induced. The mucilage and abundant soluble dietary fiber of okra can prevent the carbohydrate in intestinal tract from being digested, so as to reduce the absorption of glucose. Added to this, the mucous membrane of okra can protect the gastric wall, and the calcium content and absorptivity are higher than milk. This study uses intelligent environmental control planting system to plant okra, an environment suitable for planting okra is built, protecting crops against superheat or supercool, and protecting plants from cold damage, disease and insect damage. This study uses vacuum freeze drying method to dry okra, the moisture content after drying is recorded, and the methods to increase drying rate and shorten drying time are found out of different experimental methods. According to the vacuum freeze drying experiment, when the whole okra fruit is dried, the moisture content is as high as 69.3%, cut up into 1 cm piece, the moisture content is 11.3%, and cut up into 0.6 cm piece, the moisture content is 12.1%. The results show that the vacuum freeze drying after slicing can reduce the moisture content greatly. The same drying experiment is conducted at the okra prefreezing temperature -30℃ and prefreezing temperature -20℃. The okra at prefreezing temperature -30℃ has higher moisture content, meaning the final moisture content is poor if the prefreezing temperature is lower than the eutectic point too much. In the case of the same total drying time, the experimental results show that the end temperature heat drying has great effect on okra. The longer the end temperature heat drying distribution time is, the lower is the moisture content. Because it is difficult to remove the bound water in okra tissues during sublimation drying.

This study aimed to evaluate the spouted bed drying of okara with inert particles of polypropylene. A central composite rotatable design was carried out to verify the effect of drying air temperature and air flow on moisture content, techno-functional properties and trypsin inhibitors activity of dried product. Higher temperatures decreased emulsifying properties and trypsin inhibitor activity, probably due to thermal protein denaturation. In order to obtain a dried okara with maximum techno-functional properties and minimum moisture content and trypsin inhibitor activity, the optimal drying conditions were suggested: air temperature of 60ºC and air flow of 180 m3/h.Keywords: soy pulp; spouted bed drying; trypsin inhibitor activity; techno-functional properties; optimization