SUMMARYThe high number of cassava cultivars adapted to many different regions provides a wide variation in the chemical composition of cassava leaves meal (CLM). Therefore, the contents of some nutrients in CLM from five cultivars at three ages of the plant were investigated in order to select the cultivars and ages with superior levels of these nutrients. When the plants were 12 months old, the highest levels of crude protein (CP), β-carotene, iron, magnesium, phosphorus and sulfur were observed. The IAC 289-70 cv. showed the highest levels of magnesium, as well as considerable contents of CP, β-carotene, iron, zinc and sulfur, which did not differ statistically from the cultivars showing the highest levels of these nutrients. Keywords: cassava leaves, cultivar, minerals, vitamin, crude protein. RESUMONUTRIENTES NA FARINHA DE FOLHAS DE MANDIOCA (Manihot esculenta Crantz) EM TRÊS IDADES DA PLANTA. O número elevado de cultivares de mandioca adaptados às mais diversas regiões confere ampla variação na composição química da farinha de folhas de mandioca (FFM). Portanto, foram investigados os teores de alguns nutrientes nas FFM de cinco cultivares em três idades da planta, a fim de selecionar cultivares e idades com níveis superiores destes nutrientes. Aos 12 meses de idade da planta, observaram-se os maiores níveis de proteína bruta (PB), β-caroteno, ferro, magnésio, fósforo e enxofre. O cultivar IAC 289-70 apresentou os maiores níveis de magnésio, assim como teores apreciáveis de PB, β-caroteno, ferro, zinco e enxofre, pois não diferiu estatisticamente dos cultivares com os níveis mais elevados destes nutrientes. Palavras-chave: folhas de mandioca, cultivar, minerais, vitamina, proteína bruta.

In Brazil, the cassava leaf meal (CLM) has been used to strive against undernourishment because it is a high source of vitamins and minerals. However, the wide variation in the chemical composition of the different cultivars, as well as their antinutritional substances may be a restriction to their uses. The levels of some antinutrients in CLM from five cultivars at three ages of the plant (TAP) were investigated, in order to select the cultivars and plant ages that would be more appropriate for human consumption. The lowest contents of antinutrients were observed in the 12-month old plants, except for nitrate and hemagglutinin from which the lowest contents were found for the 17 month old ones. The cultivar IAC 289-70 had the lowest antinutrient levels, except for saponin and oxalate. Thus, the cultivar IAC 289-70 at 12 months is the most appropriate for human consumption. Keywords: cassava leaves; cyanide; polyphenol; saponin; hemagglutinin; cultivars. ResumoNo Brasil, a farinha de folhas de mandioca (FFM) vem sendo usada no combate à desnutrição por ser fonte de vitaminas e minerais. Todavia, a grande variação na composição química dos diferentes cultivares e a presença de substâncias antinutricionais tem restringido o seu uso. Investigaram-se os níveis de alguns antinutrientes da FFM de cinco cultivares em três idades da planta (TIP), a fim de selecionar cultivares e idades mais adequadas para o consumo humano. Aos 12 meses foram observados os menores teores de antinutrientes, exceto para nitrato e hemaglutinina, os quais foram inferiores aos 17 meses. O cultivar IAC 289-70 destacou-se com os menores níveis dos antinutrientes, exceto para a saponina e oxalato. Portanto, o cultivar IAC 289-70, aos 12 meses, é o mais adequado para o consumo humano.

Edible antimicrobial films are an innovation within the biodegradable active packaging concept. They have been developed in order to reduce and/or inhibit the growth of microorganisms on the surface of foods. This study developed an edible antimicrobial film based on yam starch (Dioscorea alata) and chitosan and investigated its antimicrobial efficiency on Salmonella enteritidis. A solution of yam starch (4%) and glycerol (2%) was gelatinized in a viscoamilograph and chitosan added at concentrations of 1%, 3% and 5%. Films with and without chitosan were produced by the cast method. To evaluate the antimicrobial activity of the films, two suspensions of S. enteritidis were used in BHI medium, corresponding to counts of 2 ¥ 10 8 and 1.1 ¥ 10 6 CFU/ml. The suspensions (50 ml) were poured into flasks. The films were cut into 5 ¥ 5 and 5 ¥ 10 cm rectangles to be used at ratios of 1 : 1 (1 cm 2 /ml microorganism suspension) and 2 : 1 (2 cm 2 /ml). The film 30 mm thick on average. As a control, pure chitosan at an amount corresponding to that contained in the 3% and 5% films (5 ¥ 10 cm) was added to flasks containing the microorganism suspension. Also, flasks containing only a suspension of S. enteritidis were used as control. The suspensions, in flasks, were kept at 37°C in a waterbath with agitation. Suspension aliquots were removed every hour for reading the optic density (OD 595 ) and plating onto PCA medium. The results showed that chitosan has a bactericidal effect upon S. enteritidis. Films treated with chitosan at different concentrations showed similar antimicrobial efficiency, in addition to being dependent on diffusion. The chitosan-treated films caused a reduction of one to two log cycles in the number of microorganisms, whereas the pure chitosan presented a reduction of four to six log cycles compared with the control and starch film. The films showed good flexibility.

As hortaliças não-convencionais apresentam maiores teores de nutrientes do que as convencionais, contudo seu potencial de produção e consumo é negligenciado, havendo poucas informações sobre a composição química destas espécies. Neste trabalho determinaram-se os teores de ácido ascórbico (vitamina C) e de minerais das seguintes hortaliças folhosas não-convencionais: taioba, ora-pro-nobis, bertalha e beldroega. As folhas de taioba apresentaram os maiores teores de ácido ascórbico (198,33 mg 100 g-1 de matéria fresca) e de nitrogênio (5,02 g 100 g-1), boro (0,0032 g 100 g-1) e manganês (0,007 g 100 g-1), na matéria seca (MS). As folhas da ora-pro-nobis apresentaram teores similares de ácido ascórbico e os maiores de fósforo (0,45 g 100 g-1MS) e de magnésio (0,68 g 100 g-1MS). Nas folhas da beldroega verificaram-se o maiores teores de ferro (0,032 g 100 g-1MS) e de cálcio (2,39 g 100 g-1MS). Quanto aos níveis de zinco as espécies que se destacaram foram a bertalha (0,0057 g 100 g-1MS) e a ora-pro-nobis (0,0059 g 100 g-1MS). Não houve diferença significativa entre as espécies com relação ao nível de potássio (3,71 a 3,87 g 100 g-1MS). Verificou-se que as espécies estudadas poderão se tornar boas fontes de acido ascórbico e minerais com a difusão de seu uso pela população.

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