HTST puffing in order to produce crispy banana - The effect of the step-down treatment prior to air-drying

Effect of ethanol osmotic dehydration on CO2 puffing and drying mechanism of potato

In order to further improve the drying quality of potato slices, this study investigated the effects of EPD (CO₂), HAD + EPD (CO₂), EH + EPD (CO₂), and FD on the quality and physicochemical properties of potato slices. The changes in solid loss (SL), obtained ethanol (OE), water loss (WL), and moisture content under different ethanol concentrations and soaking times were studied. The effects of WL, SL, OE, and moisture on puffing characteristics were also studied. The results show that in the EH + EPD (CO₂) process, the use of ethanol and CO₂ as the puffing media improves the puffing power. WL and OE have significant effects on hardness, crispness, expansion ratio, and ascorbic acid. The quality of potato slices puffed and dried by ethanol osmotic dehydration is better, which provides a new method for potato slice processing.

Unraveling the regulating mechanisms of moisture content in the puffing of sweet potato starch gel

Starch-based puffed crisps are a major group of popular snacks. In this work, the effects and underlying mechanisms of moisture content (MC) on the puffing of sweet potato starch gels were explored. The results showed that the gel with 12 % MC generated the highest puffing ratio (8.96), then followed by gels with 16 % MC (8.45) and 8 % MC (8.28). All starch gels presented a two-stage puffing pattern, but their evolutions with the heating temperature were highly dependent on the MC of gels. The relative puffing area percentages of gels with 8 % MC, 12 % MC and 16 % MC in the first (second) stages were 57.64 % (42.36 %), 60.66 % (39.34 %), and 18.36 % (81.64 %), respectively. The final pores in puffed products originated from the small water clusters that were regionalized in gel cells. The air cells started to expand as the gels with 8 % MC, 12 % MC and 16 % MC respectively reached the glass transition temperatures of 158.45 °C, 142.15 °C and 111.03 °C. The puffing was a joint consequence of the extensibility of cell walls and the pressure of water vapor in cells and the MC of the gels could regulate both of them. This study would facilitate the production of starch snacks with higher quality.

Effect of Sand-Frying-Triggered Puffing on the Multi-Scale Structure and Physicochemical Properties of Cassava Starch in Dry Gel

This study revealed the underlying mechanisms involved in the puffing process of dried cassava starch gel by exploring the development of the puffed structure of gel upon sand-frying, chiefly focused on the changes in the multi-scale structure and the physicochemical properties of starch. The results suggested that the sand-frying-induced puffing proceeded very fast, completed in about twenty seconds, which could be described as a two-phase pattern including the warming up (0~6 s) and puffing (7~18 s) stages. In the first stage, no significant changes occurred to the structure or appearance of the starch gel. In the second stage, the cells in the gel network structure were expanded until burst, which brought about a decrease in moisture content, bulk density, and hardness, as well as the increase in porosity and crispness when the surface temperature of gel reached glass transition temperature of 125.28 °C. Upon sand-frying puffing, the crystalline melting and molecular degradation of starch happened simultaneously, of which the latter mainly occurred in the first stage. Along with the increase of puffing time, the thermal stability, peak viscosity, and final viscosity of starch gradually decreased, while the water solubility index increased. Knowing the underlying mechanisms of this process might help manufacturers produce a better quality of starch-based puffed products.

Influence of Pear Variety and Drying Methods on the Quality of Dried Fruit

In this study, the impacts of two different pear cultivars, “Conference” and “Alexander Lucas”, on the kinetics and the final quality of samples dried by convection (CD) and microwave-convection (MCD) methods, were investigated. The quality of dried material was evaluated by the analysis of water activity, porosity, color, acoustic emission (AE) and mechanical and sensory properties. The required drying time to obtain 0.2 kg H₂O/kg dry solid (d.s.) was longer for “Conference” than “Alexander Lucas” and was 20 min by CD and 5 min by MCD. The pear cultivar, in conjunction with the drying method (CD or MCD), affected the number of AE events and the work of breaking. The CD pear of the “Conference” cultivar was characterized by higher force, higher breaking work and stronger AE relative to the CD pear of the “Alexander Lucas” cultivar. There were no differences in taste or overall quality, but the hardness was higher for the CD “Conference” pear. A principal component analysis showed that panelists preferred dried fruit with good taste and overall quality but lower hardness. A positive correlation was found between the number of acoustic events and sensory hardness; thus, an acoustic method can be useful for effectively evaluating the texture of dried pears. These results show that the dried pear slices that generated fewer AE events upon breaking were perceived as better by the panelists.