Pré-tratamentos na secagem e reidratação de champignon em fatias / Pretreatments in drying and rehydration of mushrooms slices

O objetivo deste trabalho foi avaliar o efeito de dois pré-tratamentos (pt) na desidratação osmo-convectiva: Pré-tratamento químico a 20°C por 5min em solução de ácido cítrico, bissulfito de sódio e carbonato de cálcio a 0,1% cada (pt-ABC) e por branqueamento a 80°C por 5min (pt-B), bem como a combinação pt-ABC seguido de pt-B (amostra:solução = 1:10 w/w). O pt-ABC provocou aumento de massa (13% em média) entretanto o pt-B perda (-34% em média). A desidratação osmótica a 20°C por 60min em solução de NaCl a 10% reduziu a massa de fatias não pré-tratadas em 43%. Esse nível de redução de massa não pode ser atingido com o uso do pt-ABC, mas melhorou para 49% para fatias submetidas ao pt-B. Os pré-tratamentos reduziram o tempo de secagem (70°C e com circulação de ar de 18m³ h-1) de 150min para 60min para atingir o nível de atividade de água do produto seco igual ou menor a do produto comercial. As fatias submetidas ao pt-ABC ou do controle apresentaram boa capacidade de reidratação. As fatias que foram submetidas aos dois pré-tratamentos apresentaram coloração mais clara e menos enrugadas após secagem, aparência similar foi observada às do pt-ABC. O pt-ABC pode ser usado para se obter fatias de champignon seco com aspecto visual e capacidade de reidratação adequados para o desenvolvimento de novos produtos para consumo direto ou que necessite reidratação.

The objective of this paper was assessments the effect of pre-treatment (pt) in osmo-convective dehydration: Chemical pretreatment at 20°C for 5min with 0.1% solution of citric acid, sodium bisulfite and calcium carbonate (pt-ABC) and bleaching at 80°C for 5min (pt-B), as well the combination pt-ABC followed by pt-B (sample:solution = 1:10 w/w). The pt-ABC provoked mass increase (13% on average), while pt-B caused loss (-34% on average). Osmotic dehydration at 20°C for 60 min with 10% NaCl reduced mass of slices not pretreated at 43%. This level of mass reduction was not achieved for the pt-ABC, but it was improved for 49% to slices subjected to pt-B. Pretreatments reduced drying time (70°C and air circulation 18m³ h-1) from 150min to 60min to achieve the desired a w. Water activity of dried product was equal to or less than the commercial product. Slices subjected to pt-ABC or from control group had good rehydration capacity. Slices subjected to combined pt and dried showed lighter color and were less wrinkled. pt-ABC allowed very similar results. The pt-ABC must be used to obtain slices of dry champignon with visual aspect and rehydration capacity suitable for the development of new products for direct consumption or require rehydration.

Modeling, simulation, and analysis of a reactor system for the generation of white liquor of a pulp and paper industry

An industrial system for the production of white liquor of a pulp and paper industry, Klabin Paraná Papéis, formed by ten reactors was modeled, simulated, and analyzed. The developed model considered possible water losses by the evaporation and reaction, in addition to variations in the volumetric flow of lime mud across the reactors due to the composition variations. The model predictions agreed well with the process measurements at the plant and the results showed that the slaking reaction was nearly complete at the third causticizing reactor, while causticizing ends by the seventh reactor. Water loss due to slaking reaction and evaporation occurred more pronouncedly in the slaker reactor than in the final causticizing reactors; nevertheless, the lime mud flow remained nearly constant across the reactors.