Evaluation of acid and Enzyme hydrolytic methods for the determination of cassava starch

Abstract

The starch contents of three cultivars of cassava were determined in cooked and uncooked samples with and without removal of alcohol-soluble solids. Hydrochloric acid and amyloglucosidase methods of hydrolysis were used. Hydrolysates were analysed using glucose-specific (glucose oxidase) and non-specific (ferricyanide reduction) methods. Statistical analysis of the results obtained indicated that there were no significant differences between the methods of hydrolysis and sugar analysis. The increased cost of using an enzymic method of starch analysis appears not to be justified for the determination of starch in cassava, unlike a number of other starch sources. The starch values obtained by enzymic hydrolysis of uncooked samples were significantly lower than for cooked samples. The percentage of uncooked cassava starch susceptible to enzymic degradation varied with cultivar from 14.0 to 46.88%. In view of the use of unprocessedlungelatinised cassava chips or partly gelatinised cassava pellets for animal feed, further research into cultivar variation of starch susceptibility to enzymic degradation is required.

Physicochemical properties of three sugary cassava landraces

“…Proximate composition -The following analyses were performed in the sugary cassava roots: moisture content: the gravimetric method was used in an air-circulating oven at 105°C based on AOAC (1997) method 925.10; ashes: the sample was incinerated in Mufl a oven at 550°C based on AOAC (1997) method 923.03; proteins: the Kjeldahl method was used with a 6.25 nitrogen-protein correlation factor based on AOAC (1997) method 920.87; lipids: extracted with mixing of solvents using the BLIGH & DYER (1959) method; total and reducing sugars: Lane-Eynon titration method based on AOAC (1997) method 920.183b; starch: acid hydrolysis using the RICKARD & BEHN (1987) method; insoluble and total dietary fi bers: enzymatic/gravimetric method using the α-amilase thermo-resistant (EC 3.2.1.1), protease (EC 3.4.21.26) and amyloglucosidase (EC 3.2.1.3) enzymes based on AOAC (1997) methods 985.29 and 991.42. The soluble fi ber content was determined by the difference.…”

Características físico-químicas, cozimento e produtividade de mandioca cultivar IAC 576-70 em diferentes épocas de colheita

“…Em seguida, uma porção de aproximadamente 200 gramas de cada uma das 3 raízes coletadas mensalmente, foram cortadas em fatias, secas em estufa de secagem com circulação de ar forçado à temperatura de 50°C por 48 horas, trituradas em moinho e armazenadas em frascos de vidros hermeticamente fechados. Posteriormente, depois de todas as coletas efetuadas, procederam-se as análises físico-químicas de cinzas, fibras, extrato etéreo, proteína bruta, açúcares redutores, pH, acidez (Instituto Adolfo Lutz, 1985;AOAC, 1990) e amido (Rickard & Behn, 1987).…”

Características físicas de filmes biodegradáveis produzidos a partir de amidos modificados de mandioca

“…Os amidos foram avaliados quanto aos teores de umidade por gravimetria (INSTITUTO ADOLFO LUTZ, 1986), amido por método de hidrólise enzimática (RICKARD; BEHN, 1987), seguido de dosagem de açúcares redutores por Somogy-Nelson (NELSON, 1944). O teor de amilose foi determinado de acordo com a ISO 6647 (INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, 1987).…”