O presente trabalho estabelece um método geral para se construir tabela de classificação de grãos ou outros produtos por tipo, isto é, baseado no número de defeitos contidos numa determinada amostra de produto. A teoria é formulada impondo-se a condição de que as amostras devem representar com igual precisão os tipos. É apresentada uma fórmula matemática que permite construir uma escala de classificação por tipos, partindo-se de um único ponto da escala, isto é, de um tipo cujo número de defeitos é escolhido a priori. A fórmula permite construir escalas com a precisão que se queira. Na aplicação prática, as escalas construídas matemàticamente de acôrdo com êste trabalho, devem satisfazer à condição de que os tipos estabelecidos devem ser fàcilmente diferenciáveis. O trabalho dá um exemplo de aplicação no estudo das tabelas de classíficação, por tipo, do café beneficiado.

In the commercial classification of grains it is the use to correlate the type with the aspect, or rather with the number of defects contained in a determined sample (defective grains). A scale of classification by types is nothing else than a succession A1 A2 A3 ........ An in such a way that to every A term there corresponds a certain number of defects x contained in a sample of m grains. In order that this scale of classification be adequate, at least two conditions should be fulfilled: a) the types are to be subject to differentiation by naked eye or by a procedure so much as rapid as handy; b) the samples should represent the types with one and the same precision. The first mentioned condition which is herein nominated as of practical order is determined by means of direct experimentation and after fulfilling the second one. This paper has the purpose to solve the second condition which we may nominate mathematic condition.

Em continuação a trabalhos anteriores, em 1956 foram planejadas e executadas duas séries de ensaios, com café da variedade «Bourbon Vermelho». Na primeira série, de pequenos intervalos, a matéria-prima constituiu-se de cerejas despolpadas, temperaturas de 45, 60 e 75ºC e períodos de secagem e de descanso de 1/2 x 1 hora, 1/2 x 2 horas, 1x2 horas, 1x4 horas e secagem contínua. Na segunda série, de grandes intervalos, utilizaram-se cerejas despolpadas, cerejas não despolpadas e café de «derriça», temperatura de 65ºC e períodos de secagem e descanso de 2 x 10 horas, 4 x 10 horas e secagem contínua. Nova série de ensaios foi realizada em 1961, com café em cerejas despolpadas e não despolpadas, da variedade «Mundo Nôvo», temperatura de 45, 60 e 75°C, tempos de secagem de 1, 2, 3 e 4 horas, com descanso até resfriamento, aproximadamente de 30ºC e secagem contínua. Resultados de testes organolépticos não revelaram diferenças significativas. Com base nos elementos colhidos nesses ensaios, conclui-se que: a) o parcelamento reduziu o tempo total de secagem, sehdo essa redução de tempo maior para as cerejas não despolpadas; b) no parcelamento, quanto mais baixa foi a temperatura de secagem, tanto maior a redução do tempo total de secagem; c) quanto maior o número de parcelamentos, maior a redução no tempo total de secagem; d) quando os períodos de descanso foram maiores, para um mesmo parcelamento, o tempo total de secagem foi menor; e) o parcelamento da secagem possibilitou o aumento do rendimento do secador e de sua capacidade de secagem; f) o parcelamento excessivo tornou a operação de secagem pouco prática e trabalhosa.

Experiments were carried out in 1953, 1956 and 1961 to determine the influence of the intermittent process for drying coffee. In 1956 the Bourbon Vermelho variety was used and the experiment was done in two parts: the first one, in short time intervals, with periods of drying and rest of 1/2 x 1 hour, 1/2 x 2 hours, 1x2 hours, 1x4 hours and continuous drying at 45°C, 60ºC and 75°C, using pulped cherries; the second one, in long time intervals, with periods of drying and rest of 2 x 10 hours, 4 x 10 hours and continuous drying just at 65°C using pulped cherries, unpulped cherries and coffee obtained from the usual «stripping» harvesting method. In 1961 a new experiment was performed using pulped and unpulped cherries from the Mundo Novo variety with drying periods of 1, 2, 3 and 4 hours until cooling to about 30ºC, and continuous drying. The test result did not show any statistical differences among the treatments. So, all the data together gave us the following information: a) the «parcelled» process for drying coffee reduces the total period of time and this effect is bigger for the umpulped cherries; b) in the intermittent drying process the Iowe the temperature the bigger will be the reduction of total period of drying; c) the bigger the number of «parcels» the greater the reduction of total time of drying; d) when the rest periods are large, for the same «parcels», the total time of drying is shorter; e) the intermittent drying process permits the increasing of yielding and capacity of the dryer; f) the excess of «parcels» is not recommended because it is laborious and not practical.

Em amostras de café, cujas bebidas foram submetidas à análise sensorial, apresentou-se um fato nôvo, a caracterização em algumas amostras do "gôsto de óleo". Analisando-se os ensaios que apresentaram êsse fenômeno, verificou-se que o gôsto estranho ocorria, geralmente, em amostras submetidas a' altas temperaturas de secagem e quando os testes organolépticos eram realizados após largo período de armazenamento. Dois lotes de café foram preparados em um ensaio para estudo da gustação, um constituído de cerejas não despolpadas e, outro, de cerejas despolpadas, lavadas e isentas de cascas. Ambos os lotes foram submetidos à secagem, sob a ação de ar quente a 100°C. Concluída a secagem, o material foi conservado em sacos de aniagem, idênticamente aos que davam o "gôsto estranho" ao material dos ensaios anteriores. Os testes organolépticos foram efetuados, parte em três meses depois da secagem, apresentando-se tôdas as amostras isentas de "gôsto de óleo", e parte após cêrca de doze meses, quando tôdas as amostras apresentavam o "gôsto de óleo".

In experiments carried out and later on submitted to the analysis in the Sensory Evaluation Laboratory, a new fact was noted: the panel members characterized the taste of some samples like "oil flavor". Analyzing those experiments that showed the same phenomenon, it was noted that the samples which were dried with high temperature and tasted after large storage periods were indeed classified as having a bad off-flavor similar to "oil flavor". Assuming that the association of the high temperature and large storage period produces this kind of flavor to the coffee beverage, a new experiment was designed whose aim was to prove it. Two lots of coffee samples were prepared; the pulped cherries and the unpulped ones, hoth dried at the same temperature of 100°C. (hot air temperature). After drying, the samples were stored under the same conditions as used for the previous experiments. The cup tests ware done in two ages (time): the first one in October 1961 (after three months storage) and no "oil flavor" was observed; the second age, in July 1962 (after twelve months storage) showed that all samples presented the so-called "oil flavor". Due to the economic advantage that the high temperature represents for drying coffee cherries, it is only recommended in case the product will be stored for short periods or if the final product will be industrialized at once.

Êste trabalho, que reune resultados de ensaios de secagem efetuados em Campinas pelo processo de ar quente, em um secador em forma de túnel yertical, semi-industrial e especialmente construido para êsse fim, representa uma contribuição para o estudo da desidratação de diversos dos nossos alimentos. Observou-se que os produtos amiláceos, tais como batatinha (Solanum tuberosum L.), cenoura (Daucus carota L. var. sativa D.C.), ervilhas (Pisum sativum L.), mandioca (Manikot utilissima Pohl) e mandioquinha (Arracacia xanthorrhiza Bancr.) podem ser sêcos entre 40 e 55°C de temperatura, em tempo variável de 5-10 horas, conforme a densidade de distribuição do material nas bandejas do secador. O feijão guandu (Cajanus cajan L. Millsp.) bem como a batata doce (Ipomoea batatas Lam.) constituíram exceção ao tempo de secagem, levando 15 horas para secar.

The present work summarizes the results of experiments on dehydration of vegetable foods performed at the Instituto Agronômico, Campinas. Drying was carried out by the hot air process in a drier shaped as a vertical tunnel specially built for this purpose, and which is considered very advantageous for studies on dehydration of various kinds of foodstuff. Amilaceous products such as potatoes (Salanum tuberosum), carrots (Daucus carota), peas (Pisum sativum), cassava (Manihot utilissima), and mandioquinha (Arracacia xanthorrhiza) were dried at temperatures between 40° and 55°C. The time of treatment varied for most materials from 5 to 10 hours according to the thickness the material was distributed on the shelves of the drier. The guando (Cajanus cajarn) as well as sweet potatoes (Ipomoea batatas) needed about 15 hours to be dried.

In the State of São Paulo, coffee cherries, after harvesting, are usually put to dry, in the open or are artificially dried until reaching a percentage of about 18% of water. With this humidity, the coffee husks can easily be broken by rubbing the dried cherries in the hand. This operation is done before the coffee is stored. In this paper, are presented some preliminary data about the feasibility of storage-of coffee with more than 18% of water. The results of the experiments have indicated: a) in the Campinas enrivonment, coffee can be stored with about 24% of water-without loosing color and cup-quality; b) the storage with 24% of water reduces by 20-30% the drying operation and permits better condition for more uniforme coffee drying inside the hopper (tulha). Attention has also been called for the difficulty of establishing a practical method for determination of the point when the coffee cherries attain this higher percentage of water.

In the regions of the so called "purple soils", in the State of São Paulo and Northern Paraná, coffee harvested from the ground is attended by a number of foreign matter among which lumps of soils of varying sizes make up the bulk of it. The separation of such lumps as attained by mechanical devices usually employed is always not satisfactory, the result being that remaining lumps will give a red color to the coffee beans, thus lowering the grade. Since the soil lumps have an appreciable amount of iron oxyde, mainly in the form of magnetite (Fe3O4) ; there would appear that the use of electro-magnets or permanent magnets of high power would give good results. A new machine "catador Dr. Isay" having rotative permanent magnets thus appeared in the market and tests were officiary run to determine its perfomance. It was verified that such machine performs a good job in the separation of small lumps, just the ones which are not efficiently separeted by other types of machines usually employed like "washers" (lavadores) "assorting machines" (seletores), and "stoners" (catadores de pedra). A theoretical study of the new machine "catador Dr. Isay" was also perfomed, showing that the following factors are likely to have an important bearing on its performances : a) centrifugal force to which the lumps are subjected which is dependent upon the velocity of the magnetic rolls and the lumps effective size ; b) shape of the "entre-ferro" ; c) characteristics of the material employed in the manufacture of the permanent magnet. In this respect it seems advisable to recommend the use of alnico alloys, mainly class 5 and 6.