The purpose of this experiment was to evaluate
the effects of extrusion on antioxidant abilities of the
extrudates of corn fortified with various (Chinese) yams.
The flours from three yam varieties were used, including
Dioscorea alata L. var. Tai-nung No.1 (TN1), D. alata L.
var. Ta-shan (TS), and Dioscorea doryophora var. Hang-chun
(HC). One commercial yam flour (TJ) was also used. Six
antioxidant assays were conducted, such as 1,1-diphenyl-2-
picryl-hydrazyl (DPPH) free radical scavenging effect, oxygen
radical absorbance capacity (ORAC) assay, ferrous ion
chelating (FIC) ability, 2,2-azino-bis-(3-ethylbenzothiazoline-
6-sulphonic acid) (ABTS) free radical scavenging activity,
superoxide radical scavenging (SORS) assay, and thiobarbituric
acid reactive substances (TBARS) assay. The influences of
extrusion on the antioxidant activities of corn were determinedly
different in different assays, showing a dramatic
increase of ABTS value but significant reductions of SORS
and TBARS values. The effects of extrusion on antioxidant
activities of corn–yam mixtures varied with yams in different
assays. Overall, extrusion processing increased the TBARS
inhibition ability for all yams and generally had no negative
impact on DPPH, ORAC, FIC, and ABTS antioxidant
abilities for most yams in corn–yam extrudates. The involvement
of the addition of yam to the antioxidant activities of
corn–yam extrudates during extrusion could be suggested
through two different possible approaches, the effects of
extrusion on the antioxidant activities of yams (susceptible,
resistant, or improved), and the effects of added yams on the
antioxidant activities of corn during extrusion
Pumpkin powder blended with corn flour was used in the experiment. Response surface methodology was adopted to seek the optimal extrusion conditions to develop the best quality puffing health food. The mixing ratio of pumpkin powder to the corn flour (10:90, 20:80, 30:70), as well as the water content of the mixing raw material and the extruder screw speed (250-380 rpm) were chosen as independent parameters for the extrusion process. By superimposing individual contour plots of the different responses of the four products, the optimum extrusion conditions could be derived from the identification of the meeting regions. Therefore, the graphical optimization studies resulted in 19-21%, 11.5-12.5% and 275-288 rpm of pumpkin flour level, moisture content and screw speed, respectively.
PRACTICAL APPLICATIONSAccording to the optimum conditions given to the variables, the process can be referred for industrial production and the extrudates are suitable for extruded snack food with pumpkin flour.
The lesser grain borer Rhyzopertha dominica is the major pest of stored paddy rice globally, including in Taiwan. It has strong phototaxis and is good at flying, suitable for developing a light-trapping method to monitor and control it. In the present study, a wavelength of light-emitting diodes (LEDs), i.e., 373 nm, was determined to be the most efficient to trap R. dominica using a dodecagon maze. Accordingly, an LED trap, named the Taiwan Agricultural Research Institute-LED (TARI-LED) trap, was invented, which comprised LEDs of two distinct wavelengths (373 and 408 nm), a wavelength switch, a suction fan, and an insect collector. The trapping efficiency was assessed in a 4-m3 laboratory arena and two paddy rice storehouses. An initial assessment was performed in the laboratory arena and showed that the TARI-LED trap with 373-nm wavelength for R. dominica rapidly increased in the first 30 min, reaching the highest trapping rate (68.5%) after 3 h. In addition, no significant difference was observed between the suction fan turned on or off. The field tests showed that the 373-nm wavelength had the highest effectiveness for trapping R. dominica in the two paddy rice storehouses, and no significant difference was observed in the number of R. dominica trapped by the 373-nm TARI-LED trap or the CDC-UV light trap. In conclusion, our TARI-LED trap 373 nm exhibited high efficiency in trapping R. dominica in paddy rice storehouses. Moreover, a suction fan-free design should benefit long-term and safe use in paddy rice storehouses trapping R. dominica.
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