Changes in the contents of carotenoids and their true retentions (% TR) during the production of puree of Cucurbita moschata 'Menina Brasileira' and of Cucurbita maxima 'Exposição' pumpkins and the stability of such compounds during 180days of storage were monitored by liquid chromatography coupled with a photodiode array detector. Cooking caused higher losses than commercial sterilisation. High losses of xanthophylls such as lutein and violaxanthin were noted during processing and storage of pumpkin puree. Such losses show the low stability of these compounds. The major carotenoids, pro-vitamin A carotenes, namely, α-carotene and all-trans-β-carotene for C. moschata 'Menina Brasileira' and all-trans-β-carotene for C. maxima 'Exposição' obtained high retentions (>75%) after processing. A slight degree of isomerisation of β-carotene was noted in the puree samples, but with low concentrations of cis-isomers. Storage for 180days did not significantly affect (P⩽0.05) the concentrations of these carotenoids.

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Purees of Cucurbita moschata 'Menina Brasileira' and of Cucurbita maxima 'Exposic¸a˜o' pumpkins were produced. A commercial sterilisation test confirmed the effectiveness of the thermal treatment applied in the production. The stability was monitored during storage in ambient conditions. No significant alterations in pH, titratable acidity or soluble solids were noted. Both types of puree have a good concentration of carotenoids, although a slight decrease was detected in the 'Exposic¸a˜o' pumpkin puree after 15 days of storage. In relation to the colour of the purees, there were no significant alterations in a*, b* or DE during storage. Decreases in L* and WI were detected after 30-60 days of storage, thus suggesting a browning in an initial period. However, the scores given by the sensory assessors remained above 7 in a 9-point scale, thus showing no significant alterations during storage. The results showed the stability of the pumpkin purees during the 180 days of storage under the proposed conditions.

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Leaves of erva-mate (Ilex paraguariensis St. Hill) were heat treated with different combinations of time and temperature. Polyphenol oxidase (PPO) and peroxidase (POD) residual activities and colouring (L, a, b and DE) were studied after treatment for 3 weeks. The best results for enzyme inactivation after heat treatment were obtained with the leaves treated at 450°C for 15 s and at 500°C for 10 s, with reductions of 90.6% and 83.4% for PPO and 94.5% and 92.7% for POD. These groups also showed low levels of enzyme activity during the first few days of storage, and a few days later no enzyme activity was detected. The data on the colours, specially -a values (green colour), were in accordance with results for enzyme activity and helped in the research on the changes that occur in the leaves during storage. Data from this work can be suggested for the improvement of the current method of erva-mate processing, which is still performed empirically.