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Convective drying is a widely used conservation process, and in an attempt to improve it, the use of ultrasound and/or vacuum can be an alternative. The objective of this work was to evaluate the influence of ultrasonic waves and vacuum, combined or not, on the drying kinetics at 60 °C and the impact in terms of fruit quality, through the following techniques: ultrasonic assisted drying (USD), vacuum drying (VD), ultrasonic assisted vacuum drying (USVD) and control drying (CD). Six different semi-theoretical drying mathematical models were compared based on their coefficient of determination and mean square error to characterize the drying curves. The application of the USVC technique resulted in a higher rate drying kinetics and a reduction of the process time above 50%. The dehydrated kinetics was successfully described by the Two-terms Exponential model. Effective moisture diffusivities were in the range of 10−9 m2/s and the higher value was obtained for USVD. It was verified that the use of ultrasound (USD and USVD) had a strong influence in obtaining the highest retention of polyphenols, while the use of vacuum (VD and USVD) resulted in lower color differences of processed samples in relation to fresh fruit and lower energy consumption. Thus, the combined use of ultrasound and vacuum can provide satisfactory results.

Melon fortification with calcium by impregnation techniques using a vacuum and/or ultrasound and drying were combined to obtain a snack product. For the impregnation step, samples were immersed in a 2 g 100 mL(−1) calcium chloride solution at 25 °C. The samples were dried at 60 °C and an air velocity of 2 m s(−1). The influence of the impregnation method on drying kinetics, mass variation, calcium content, water activity, color, and texture was evaluated. All dried samples had reduced water activity. The vacuum impregnated (VI) melons presented higher mass gain and drying time. It resulted in the highest calcium incorporation, increasing up to 13 times the calcium concentration of the samples. The samples dried after submitted to VI showed the greatest differences in color and hardness. However, VI was the most effective technique for calcium incorporation, being the only one capable of producing fortified dried melon.

Research background: Drying is one of the most traditional processes of food preservation. Optimizing the process can result in a competitive product on the market regarding its price and quality. A common method in use as a pretreatment to drying is ultrasound. The goal of this work is to analyze different drying methods with and without applying ultrasound (US) pretreatment, on heat and mass transfer, simulating numerically the temperature profile by computational fluid dynamics (CFD). Experimental approach: The melon slices were pretreated with ultrasound for 10 (US10), 20 (US20) and 30 (US30) min at 25 kHz, and the water loss and solid gain were evaluated. Samples were dried at different temperatures (50, 60 and 70 °C). The effective diffusivity was estimated, and experimental data were modelled using empirical models. The airflow in the dryer and the temperature profile in the melon slice were simulated via computational fluid dynamics (CFD). Results and conclusions: Ultrasound pretreatment reduced the drying time from 25% (samples US20 and US30 at 50 °C) to 40% (samples US20 and US30 at 70 °C). The two-term exponential model presented the best fit to the experimental data, and the diffusivity coefficients showed a tendency to increase as the time of exposure of the melon to ultrasonic waves increased. Pretreatment water loss and solid gain behaviour and drying kinetic and diffusion data were used to choose the best experimental conditions to be simulated with CFD. The heat transfer modelling through CFD showed that the temperature distribution along the melon slice was representative. Therefore, the profile obtained via CFD satisfactorily describes the drying process. Novelty and scientific contribution: The use of simulation tools in real processes allows the monitoring and improvement of existing technologies, such as food drying processes, that involve complex mechanisms, making it difficult to obtain some data. Application of CFD in the drying processes of fruits and vegetables is still very recent, being a field little explored. There is no record in the literature that uses CFD in the drying of melon., Pozadina istraživanja. Sušenje je jedan od najtradicionalnijih postupaka konzerviranja hrane. Optimiranjem postupka sušenja dobivaju se proizvodi koji su cijenom i kakvoćom konkurentni na tržištu. Primjena ultrazvuka je uobičajena metoda prethodne obrade proizvoda prije sušenja. Svrha je ovoga rada bila ispitati različite metode sušenja s prethodnom obradom ultrazvukom ili bez nje na prijenos topline i mase, te napraviti simulaciju temperaturnog profila primjenom računalne dinamike fluida. Eksperimentalni pristup. Kriške dinje su prethodno obrađene ultrazvukom pri 25 kHz tijekom 10, 20 i 30 min, te su izmjereni gubitak vode i povećanje mase suhe tvari uzoraka. Uzorci su zatim sušeni pri temperaturama od 50, 60 i 70 °C. Procijenjena je efektivna difuzivnost vode, a eksperimentalni su rezultati oblikovani pomoću empirijskih modela. Protok zraka u sušari i promjena temperature u krišci dinje simulirani su pomoću računalne dinamike fluida. Rezultati i zaključci. Prethodnom obradom ultrazvukom vrijeme se sušenja smanjilo od 25 % (za uzorke obrađene ultrazvukom tijekom 20 i 30 min, a zatim sušene na 50 °C) do 40 % (za uzorke obrađene ultrazvukom tijekom 20 i 30 min, a zatim sušene na 70 °C). Dvočlani eksponencijalni model najbolje je opisao eksperimentalne podatke, a koeficijent difuzivnosti povećavao se s produljenjem obrade uzoraka dinje ultrazvukom. Gubitak vode i povećanje mase suhe tvari tijekom prethodne obrade ultrazvukom, te kinetika sušenja i podaci o difuzivnosti korišteni su za odabir najboljih eksperimentalnih uvjeta i njihovu simulaciju pomoću računalne dinamike fluida. Modeliranjem prijenosa topline potvrđeno je da je distribucija topline u kriški dinje bila u skladu s očekivanjima. Stoga je zaključeno da temperaturni profil dobiven računalnom dinamikom fluida na zadovoljavajući način opisuje postupak sušenja. Novina i znanstveni doprinos. Alati za simulaciju stvarnih procesa omogućuju praćenje i poboljšanje postojećih postupaka obrade hrane kao što je sušenje, koje uključuje kompleksne mehanizme, što otežava dobivanje podataka. Primjena računalne dinamike fluida pri sušenju voća i povrća je noviji i slabo istražen postupak. U znanstvenoj literaturi nema podataka o upotrebi računalne dinamike fluida pri sušenju dinje.

This paper aims at developing reflections about the relationship between the composition of youth in the last few decades in Brazil and the configuration of public policies for this segment. It assumes that the youth is a complex social phenomenon, and it is inserted into a concrete social-historical reality that reflects the tension, conflicts and contradictions that constitute capitalistic society. This analysis is developed from three fields of knowledge: sociology, demography and politics. With demography, we debate numbers, the configuration of the “youth wave” phenomenon through coortes juvenis and its impacts, confronting this process with the concepts of demographic bonus and window of opportunities. From a sociological point of view, we analyze both the impact of the volume of these coortes juvenis and what the youth represents in creating of public policies. As a parameter, data from two documents that diagnose Brazilian youth are used, each one produced by federal institutions on distinct moments: CNPD 1998 and SAE/PR/IPEA 2013. They helped understand the composition of the demographic transition scenario and the transformation of the age structure in the last few decades. We asked if the public policies and government actions developed in the time between the two studies mentioned above effectively considered the impact and importance of this phenomenon, which, according to demographics, only happens once in the history of a country. As a conclusion, going beyond demographics, youth is a complex social phenomenon in the sense that it is appropriated by capitalism, as a fetish for consumer goods and as an exploration of workforce, while public policies try to reach the reality of this phenomenon.

Submitted by Luiz Nicoli Junior (luiz.nicoli@fdv.br) on 2021-02-09T13:47:18Z No. of bitstreams: 1 921-Texto do artigo-2532-1-10-20170310.pdf: 981453 bytes, checksum: 6fee85bb677b8f459288a211908ce3c8 (MD5) Approved for entry into archive by Ana Paula Galdino (repositorio@fdv.br) on 2021-02-10T17:38:07Z (GMT) No. of bitstreams: 1 921-Texto do artigo-2532-1-10-20170310.pdf: 981453 bytes, checksum: 6fee85bb677b8f459288a211908ce3c8 (MD5) Made available in DSpace on 2021-02-10T17:38:08Z (GMT). No. of bitstreams: 1 921-Texto do artigo-2532-1-10-20170310.pdf: 981453 bytes, checksum: 6fee85bb677b8f459288a211908ce3c8 (MD5) Previous issue date: 2016-12-31 Tem como objetivo desenvolver reflexões sobre a relação entre a composição da juventude nas últimas décadas no Brasil e a configuração das políticas públicas para esse segmento. Parte do pressuposto de que a juventude, é um fenômeno social complexo e está inserido em uma realidade/concretude sóciohistórica que reflete as tensões, conflitos e contradições constitutivos da sociedade capitalista. A análise é desenvolvida a partir da fronteira entre três campos do saber: sociologia, demografia e política. Com a demografia debate os números, a configuração do fenômeno da onda jovem por meio das coortes juvenis e seus impactos, problematizando esse processo com os conceitos de bônus demográfico e janela de oportunidades. A partir da sociologia analisa tanto o impacto do volume dessas coortesjuvenis, quanto as representações de jovensno desenho das políticas públicas. Utiliza como parâmetro de análise de dados dois documentos de diagnósticos sobre ‘juventudes’ brasileira, produzidos por instituições do governo federal em momentos distintos - CNPD 1998 e SAE/PR/IPEA 2013 - como forma de entender o cenário de composição da transição demográfica e a transformação da estrutura etária das últimas décadas. Questiona se as políticas públicas e ações do governo desenvolvidas no decurso do tempo transcorrido entre os dois diagnósticos, considerou realmente o impacto e a importância desse fenômeno que, segundo, os demógrafos, ocorre apenas uma vez na história dos países. Conclui-se que, para além da dimensão demográfica, a juventude, como um fenômeno social complexo, na medida em que, tanto em nível de fetiche de mercadoria, como de exploração do trabalho, é apropriado pelo capitalismo, ficando as políticas públicas na busca do alcance da realidade desse fenômeno This paper aims at developing reflections about the relationship between the composition of youth in the last few decades in Brazil and the configuration of public policies for this segment. It assumes that the youth is a complex social phenomenon, and it is inserted into a concrete social-historical reality that reflects the tension, conflicts and contradictions that constitute capitalistic society. This analysis is developed from three fields of knowledge: sociology, demography and politics. With demography, we debate numbers, the configu-ration of the “youth wave” phenomenon through coortes juvenis and its im-pacts, confronting this process with the concepts of demographic bonus and window of opportunities. From a sociological point of view, we analyze both the impact of the volume of these coortes juvenis and what the youth repre-sents in creating of public policies. As a parameter, data from two documents that diagnose Brazilian youth are used, each one produced by federal institu-tions on distinct moments: CNPD 1998 and SAE/PR/IPEA 2013. They helped understand the composition of the demographic transition scenario and the transformation of the age structure in the last few decades. We asked if the public policies and government actions developed in the time between the two studies mentioned above effectively considered the impact and impor-tance of this phenomenon, which, according to demographics, only happens once in the history of a country. As a conclusion, going beyond demographics, youth is a complex social phenomenon in the sense that it is appropriated by capitalism, as a fetish for consumer goods and as an exploration of workforce, while public policies try to reach the reality of this phenomenon