Effect of sugar and water contents on non-expanded cassava flour extrudates

The effects of sucrose and water contents on cassava flour processed by extrusion at varied concentrations of sucrose (0-20% w/w) and water (28-42% w/w) were studied by applying response surface methodology. The extrusion of the mixtures was performed in a twin screw extruder fitted to a torque rheometer. The specific mechanical energy (SME) dissipated inside a conical twin-screw extruder was measured. Water absorption index (WAI), water solubility index (WSI) and paste viscosity readings (cold viscosity (CV), peak viscosity (PV), breakdown (BD) and set back (SB)) during a gelatinization-retrogradation cycle measured in a Rapid Visco Analyzer were determined on non-directly extruded products. The results indicated that SME and WSI decreased as a function of water and sucrose contents. WAI and pasting properties were influenced by water content. A non antiplasticizing effect of the sucrose content was observed on pasting properties, suggesting that sucrose did not reduce the availability of water available for gelatinizing cassava flour during the extrusion process. The nature of the optimum point was characterized as a saddle point for WAI, WSI, PV and BD, whereas SME showed a maximum and CV and SB a minimum. The results indicated to be valuable for the production of non-expanded cassava flour extrudates with desirable functional properties for specific end users.

Volatile profile and physical, chemical, and biochemical changes in fresh cut watermelon during storage

Existing data about the aroma of fresh-cut watermelon and the metabolic changes that occur with minimal processing are scarce. Given the close relationship that exists between aroma, texture, and quality characteristics, it is necessary to investigate the changes in the volatile profile and texture of watermelon, a fruit extensively sold in supermarket chains throughout Brazil. The objective of this work was to analyze the volatile profile using solid phase microextraction (SPME) as well as texture changes in fresh-cut watermelon stored at 5 °C for ten days. Chromatography associated with sensory analysis (sniffing) led us to conclude that 9-carbon (C9) alcohols and aldehydes are the major responsible for the flavor and aroma of minimally processed watermelon stored at 5 ± 1 °C/90 ± 5% RH for ten days, and also that the aroma diminishes in intensity with storage, but it does not affect the final quality of the product. It was noted that the amount of drained liquid, soluble pectin, and weight loss increased during storage concurrently with a reduction in firmness and a structural breakdown of the cells. Pectin methyl esterase activity remained constant and polygalacturonase activity was not detected.

Characterization and nutritional value of precooked products of kiwicha grains (Amaranthus caudatus)

AbstractKiwicha has significant nutritional characteristics. It is commonly used as a puffed product, but there is little research on the lamination process. In this paper, the physical, functional properties, chemical composition and acceptability of the precooked kiwicha grains were studied. Puffed (PK) and laminated kiwicha (LK) were made. Puffed amaranth (CPA) was used as a commercial reference standard. The raw grain (RG) showed a higher bulk density (0.85 g/ml) than in PK (0.18 g/ml) and LK (0.38 g/ml). Both products had a good expansion. The yellow index decreased in PK (50.92) and LK (45.87) respect to RG (65.64). The largest was CPA (58.54). In all the products, the precooking increased the index of absorption, solubility and swelling power. Also, they showed major pasting temperature, low peak viscosity and breakdown viscosity. In both formulated products, the content of total, soluble and insoluble dietary fibre decreased during the precooking process. The content of protein was optimal (between 14.57-14.59 g/100g). PK had high acceptability (5.84), preference (84.48%), purchase (38.79%) and consumption (43.96%) intention. The lowest was CPA. This work demonstrates that it’s feasible to make precooked products with good quality characteristics, chemical composition and acceptability for the development of new products.