Changes in physicochemical properties of corn kernels as affected by roasting temperature and time were investigated and described using mathematical equations. Corn kernels were roasted for up to 50 min at 160, 180, 200, 220 and 240C. The weight, bulk density, soluble solids, pH, browning index and phenolic compounds of roasted corn were assayed throughout the roasting process. The levels of weight, bulk density and pH of corn decreased, while the levels of soluble solids, browning index and phenolic compounds increased, when the roasting temperature and time increased. The higher chemical changes in corn occurred at above 200C. The change patterns in the levels of soluble solids and phenolic compounds during roasting satisfactorily followed first‐order and zero‐order equations, respectively. Temperature dependence of these changes was described by Arrhenius equation.
PRACTICAL APPLICATIONS
Corn (Zea mays L.) is treated by various food processing technologies including roasting in order to be consumed as foodstuff. Quality and utilization of roasted corn may be dependent on the roasting conditions. However, the control of roasting process is roughly carried out by an experience of operators. In the present study, the changes in physicochemical properties of corn kernels during roasting process were determined. The results showed that physicochemical changes in corn were significantly affected by the roasting temperature and time. Thus, roasting temperature and time should be quantitatively controlled to obtain a desired quality of the roasted corn kernels. The change kinetics of physicochemical property obtained in this study could be considered as an indicator for quality control in roasting processes dependence on the utilization of the roasted corn kernels.
Unripe apples are discarded due to thinning out or falling in orchards, however they are abundant in functional ingredients. In this study, polyphenols were efficiently enzymatically extracted and isolated from unripe apples. Enzymatic extraction of polyphenols over 12 hours followed using Viscozyme L with an enzyme concentration of 2%(v/w) based on the total phenolic content. In order to isolate the polyphenols, extracts of unripe apples were eluted with water, 25, 50, 75 and 100% ethanol using Diaion HP-20 gel column chromatography. Polyphenol compounds of each fraction were analyzed by high performance liquid chromatography (HPLC), with the 50% ethanol fraction containing the most polyphenols (387.88 μg/mL of caffeic acid, 226.34 μg/mL of p-coumaric acid, and 187.33 μg/mL of phloridzin). The 50% ethanol fraction also contained the most antioxidants (total penolic and flavonoid content; p<0.05). Antioxidant assays using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and ferric ion reducing antioxidant power (FRAP) activity exhibited the highest activities in the 50% ethanol fraction (p<0.05). Antimicrobial activities were also assessed as being highest in 50% ethanol fraction (p<0.05). The 50% ethanol fraction of unripe apple enzyme extracts can be used as a functional polyphenol material to improve the utilization of unripe apple.
This study was conducted to establish the shelf life of β-glucan microcapsules from the medicinal mushrooms (Phellinus baumii and Ganoderma lucidum). Changes in the quality attributes, including moisture content, color, and total bacterial count, of the β-glucan microcapsules were analyzed during storage for 5 months at 10℃, 25℃, and 40℃. The moisture content of β-glucan microcapsule from P. baumii did not show any significant difference during storage at 25℃ and 40℃, but decreased after 3 months storage at 10℃. The moisture content of the β-glucan microcapsule from G. lucidum showed slight increase and decrease during storage at 25℃ and 40℃, but at 10℃, showed an initial decrease for 3 months and then increased. ΔE values of β-glucan microcapsules from P. baumii and G. lucidum did not change during 5 months at various storage temperatures. The total bacterial count of the microcapsules from both P. baumii and G. lucidum maintained their initial values without significant changes according to storage period and temperature. Overall, the shelf life of β-glucan microcapsule from P. baumii was determined to be 30.11 months according to the moisture content and β-glucan microcapsule from G. lucidum was determined to be 24.82 months according to the total bacterial count. Thus, it is desirable to establish the storage period of 24 months at 25℃.
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