Use of multi-response modelling to investigate mechanisms of β-carotene degradation in dried orange-fleshed sweet potato during storage: from carotenoids to aroma compounds

In order to give insight into β-carotene degradation mechanism during the storage of dried orange-fleshed sweet potato, and particularly into the role of isomers and norisoprenoids formation, multi-response kinetic modelling was applied. Determination of degradation compounds were carried out by HPLD-DAD and SPME-GC-MS as a function of time between 10 and 40 °C and at four water activities from 0.13 to 0.76. Kinetic modelling was developed assuming first-order reactions and by using mass balance. Eight compounds, namely, two isomers (9-cis- and 13-cis-β-carotene), two β-carotene epoxides (β-carotene 5,6 and 5,8 epoxide) and four volatile compounds (β-cyclocitral, β-ionone, 5,6-epoxy-β-ionone and dihydroactinidiolide), were integrated into two theoretical reaction schemes. The different models were discriminated according to goodness of fit to experimental data. This work showed that: (1) the formation of cis-isomers from β-carotene preceded oxidation, (2) β-cyclocitral arose directly from β-carotene scission while the other norisoprenoids resulted from β-carotene epoxide degradation, (3) cis-isomers were high reactive compounds. Temperature had a major influence on reaction rates k while water activities only impacted k at values under 0.51. Therefore, multi-response modelling is not only a tool to predict β-carotene degradation but a interesting way to select the appropriate degradation scheme based on the different options presented in literature

Produção e aceitabilidade de cenoura sob cultivo orgânico no inverno e no verão Production and acceptability of carrot under organic cultivation in winter and summer

Para o cultivo da cenoura é importante conhecer a adaptação das cultivares de acordo com as condições climáticas do local e a preferência do consumidor. Com o objetivo de avaliar o desempenho e a aceitação, detectando assim a preferência dos consumidores a diferentes cultivares de cenoura em sistema de cultivo orgânico, realizou-se o presente trabalho. Avaliou-se o desempenho das cultivares de cenoura em Dois Vizinhos (PR). O delineamento experimental utilizado foi blocos casualizados com cinco repetições e quatro tratamentos para a época de inverno (cvs Nantes, Shin Kuroda, Danvers e Flaker) e cinco tratamentos para o verão (cvs Shin Kuroda, Kuronan, Brasília, Esplanada e Carandaí). Avaliou-se a resistência à queima das folhas (Alternaria dauci), incidência de ombro verde, sólidos solúveis totais, produtividade e aceitabilidade, por meio de análise sensorial das cenouras in natura e em conserva tipo picles. Para o cultivo de inverno a cultivar Nantes resultou em maior produtividade (29,02 t ha-1) e para o cultivo de verão a produtividade da cultivar Esplanada foi superior (32,0 t ha-1) às demais cultivares, que não diferiram estatisticamente entre si. A cv. Esplanada apresentou maior resistência à queima das folhas e menor percentagem (5,6%) de ombro verde. As características organolépticas das cultivares apresentaram boa aceitabilidade pelos consumidores participantes.<br>For the carrot cultivation it is important to understand the adaptation of cultivars according to the local weather conditions and consumer preference. The objective was to evaluate the performance and acceptance, thereby detecting the consumer's preference for different carrot cultivars in organic cropping system. The performance of the cultivars Nantes, Shin Kuroda and Danvers Flaker was evaluated in the winter season and cultivars Shin Kuroda, Kuronan, Brasilia, Esplanada and Carandaí for cultivation of summer in Dois Vizinhos, Paraná state, Brazil. The experimental design was randomized blocks with five replications and four treatments for the winter season and five treatments for the summer season. We analyzed the resistance to leaf blight (Alternaria dauci), incidence of green shoulder, total soluble solids, yield and acceptability through sensory analysis of fresh carrots and canned pickles type. On the winter crop, cultivar Nantes resulted in higher yield (29.02 t ha-1) and on the summer crop cultivar Esplanada productivity was higher (32.0 t ha-1) without statistical difference. The cv. Esplanada was more resistant to leaf blight and presented the lowest percentage (5.6%) of green shoulder. For sensory analysis, the cvs presented good acceptability from the participating consumers