• Environmental Engineering Research
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• v.24 no.2
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• pp.354-361
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• 2019

Renewable energy from biomass and biodegradable wastes can significantly supplement the global energy demand if properly harnessed. Pyrolysis is the most profound modern technique that has proved effective and efficient in the energy conversion of biomass to yield various products like bio-oil, biochar, and syngas. This study focuses on optimization of slow pyrolysis of banana peels waste to yield banana peels vinegar, tar and biochar as bio-infrastructure products. Response surface methodology using central composite design was used to determine the optimum conditions for the banana wastes using a batch reactor pyrolysis system. Three factors namely heating temperature ($350-550^{\circ}C$), sample mass (200-800 g) and residence time (45-90 min) were varied with a total of 20 individual experiments. The optimal conditions for wood vinegar yield (48.01%) were $362.6^{\circ}C$, 989.9 g and 104.2 min for peels and biochar yield (30.10%) were $585.9^{\circ}C$, 989.9 g and 104.2 min. The slow pyrolysis showed significant energy conversion efficiencies of about 90% at p-value ${\leq}0.05$. These research findings are of primary importance to Uganda considering the abundant banana wastes amounting to 17.5 million tonnes generated annually, thus using them as pyrolysis feedstock can boost the country's energy status.

• Journal of the Korean Wood Science and Technology
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• v.51 no.2
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• pp.98-108
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• 2023

In this study, the boards were manufactured according to the mandarin peels addition rate using sawdust and mandarin orange peel. After that, the mechanical properties and density profile of ceramics prepared by conditions through resin impregnation process and carbonization process were investigated. The bending and compression strengths of ceramics tended to increase as the resin impregnation rate increased. When the resin impregnation rate was 70%, the highest values were 8.58 MPa and 14.77 MPa, respectively. Also, the mechanical properties of ceramics according to carbonization temperature showed the highest values at 1,200℃ for bending strength of 11.09 MPa and compression strength of 17.20 MPa. The bending strength and compression strength according to the mandarin peels addition rate showed the highest values at 8.62 MPa and 14.16 MPa, respectively, when the mandarin orange peel addition rate was 5%. The mechanical properties tended to decrease when the addition rate of mandarin orange was increased. The density profile of ceramics showed a similar tendency to the mechanical properties. It can be seen that the density distribution from the surface layer to the center layer is more uniform as the resin impregnation rate and carbonization temperature increase and the mandarin peels addition rate decreases.

• Journal of Nutrition and Health
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• v.31 no.4
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• pp.809-822
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• 1998

Retarding effects of the dietary fibers from persimmon peels (PTDF ; total dietary fibers, PIDF ; insoluble dietary fibers, PSDF ; soluble dietary fibers) and dried jujubes (JTDF ; total dietary fibers, JIDF ; insoluble dietary fibers, JSDF ; soluble dietary fibers) on glucose, bile acid and cadmium transport were evaluated by in vitro dialysis sack method. These effects were compared with those of commerical citrus pectin, CM-cellulose (CMC) and $\alpha$-cellulose. Yields of PTDF, PIDF and PSDF on wet weight basis were 14.04% , 11.61%, 1.76%, respectively, and those from dried jujubes were 14.80%, 9.98% and 2.80%, respectively. The amount of soluble fibers in JTDF was higher than PTDF. Soluble fibers had the retarding effects on glucose transport but insoluble fibers did not have. CM-cellulose showed the greatest retarding effect, which was followed by citrus pectin and JSDF. Among the soluble fibers, PSDF had the lowest retardig effect. Retarding effect of TDF was dependent upon the amount of SDF in TDF. Regarding bile acid dialysis , insoluble dietary fibers as well as soluble dietary fibers showed the retarding effects, among which JSDF had the greatest retarding effects, among which JSDF had the greatest retarding effect, followed by citrus pectin. Among the extracted fibers, dietary fibers from dried jujubes were more effective than these from persimmon peels, and SDF seemed to show higher retarding effects than IDF and TDF. On cadmium transport retardation , all dietary fibers except $\alpha$-cellulose had the retarding effects and PSDF showed the greatest effect which was followed by PIDF and CMC, The extracted fibers showed higher retarding effect on Cd transport than glucose and bile acid transport, and dietary fibers from persimmon peels showed higher retarding effects than those from dried jujubes.

• Food Science and Preservation
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• v.30 no.2
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• pp.321-333
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• 2023

The study investigated the pH, acidity, soluble solids, total sugar, polyphenol, flavonoid, anthocyanin content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and color of kombucha with a variety of added fruit peels during the fermentation process. Pear, grape, plum, orange, apple, and golden kiwi peels were added during fermentation. The pH showed a decrease, while an increase in acidity was observed. An increase in soluble solids, which was higher in most experimental groups than the control group, was also observed. A decrease in total sugar was observed over time. However, an increase was observed in reducing sugar. On Day 0, higher total sugar and reducing sugar were detected in the peel addition group compared with the control group. The antioxidant capacity of polyphenol, flavonoid, anthocyanins, and DPPH radicals scavenging increased with fermentation and was higher in all addition groups, except for pear, compared with the control group. Except for grapes and plums containing high levels of anthocyanins, an increase in the L-value was observed over time, and an increase in the a-value of grapes and plums was also observed (p<0.05). The possible utilization of inedible fruit peel in kombucha was shown. Applying inedible fruit peels to kombucha is proposed to increase antioxidant content and modulate color and pH.

• Korean journal of food and cookery science
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• v.26 no.1
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• pp.18-25
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• 2010

This study was carried out to investigate the total polyphenol and flavonoid contents and antioxidative activities of enzymatic digests from dried Citrus unshiu and C. grandis peels. The yields of digests from dried C. unshiu and C. grandis peels were high in viscozyme (a carbohydrase) and kojizyme (a protease), and enzymatic digests from dried C. grandis peels appeared highly comparable to those of C. unshiu. Total polyphenol contents were high in ultaflo (a carbohydrase) and alcalase and flavourzyme (proteases), and the digests from dried C. unshiu peels appeared high in comparison to C. grandis. Total flavonoid contents were high in ultaflo, alcalase, and water extract. DPPH radical scavenging activities appeared very high in digests from dried C. grandis peels in comparison to C. unshiu, and was the highest in viscozyme and kojizyme. The viscozyme digest displayed particularly high activity. Hydrogen peroxide scavenging activities increased somewhat with increasing amounts of digests, but displayed very high activity, more than 91%, except kojizyme the digest from dried C. unshiu peel, at 2.0 mg/mL. Alkyl radical scavenging activities increased rapidly with increasing amounts of digest, and all enzyme digests from dried C. unshiu and C. grandis peels displayed very high activities at more than 0.5 mg/mL. Hydroxyl radical scavenging activities increased rapidly with increasing amounts of digests, and all enzymatic digests from dried C. unshiu and C. grandis peels displayed relatively low activities in comparison to other activated oxygen species.

• Food Science and Preservation
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• v.24 no.8
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• pp.1088-1093
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• 2017

This study was conducted to investigate the effects of drying methods for Citrus junos peels on quality characteristics of the hot-water leachate from teabags containing those peels. Fresh peels were hot-air ($50^{\circ}C$), cold-air ($30^{\circ}C$), or freeze-dried ($-45^{\circ}C$), powdered to a size of 40 mesh, packaged with a paper sachet, and then the packaged teabags were leached for 10 min with hot-water ($70^{\circ}C$). $L^*$ value (lightness) and $-a^*$ value (greenness) of the peel powder were the highest in the freeze-dried samples. Soluble solids and titratable acidity of the teabag leachate were in the following order; cold-air, freeze, and hot-air dried samples. Among free sugar contents in all samples, fructose content was the highest, followed by glucose and sucrose. Fructose and glucose contents were not affected by drying methods. There was no significant difference in the flavonoid content among the peels dried using three drying methods. DPPH radical-scavenging activity of the leachate was the highest in the cold-air dried sample. These results suggest that cold-air drying would be an effective method to enhance the quality of hot-water leachate of teabags prepared from C. junos peels.

• Food Science and Preservation
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• v.9 no.3
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• pp.327-331
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• 2002

To develop the use of natural pigment for food, anthocyanins were isolated from grape peels which were wasted much in korea, and their characteristics were as fellows. pH has a marked influences on the color of the grape peels anthocyanin solution(GPAS). At low pH the color of GPAS was more stable than high pH. With increasing pH the color gradually fades as colorless pseudobases are formed. It showed characteristic bathnochromic shift as the solution increased. Among the sugars tested, glucose showed the most protective effect on the color of GPAS to raise the color stability, while fructose showed an adverse effect. Orgarnic acid such as citric acid prevented the degradation of anthocyanin, but ascorbic acid lowered stability of color considerably. The effect of light on GPAS was found to be very deleterious. The pigment degradation can be minimized by shielding the light from the pigment solution.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.418-426
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• 2015

Total phenol contents, total flavonoid contents and antioxidant activity of 70% methanol, 70% ethanol and chloroform-methanol (CM, 2:1, v/v) extracts from onion (Allium cepa L.) peels were studied. The $IC_{50}$ values of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity in 70% ethanol extract were remained to be lowest followed by 70% methanol extract and CM extract. And the total phenol content ($113.56{\pm}0.86mg\;CAE/g$), total flavonoid content (49.63 mg QE/g) and ferric reducing antioxidant power value were also found to be the highest. In contrast, 70% methanol extract possessed the strongest antioxidant activity by ${\beta}$-carotene bleaching assay. CM extract displayed the lowest antioxidant activity compared with other extracts. Onion peels exhibited strong antioxidant activity and abundant phytochemicals, which could be used in a various food products to add phytochemicals and promote good health.

• The Korea Journal of Herbology
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• v.23 no.4
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• pp.159-170
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• 2008

Objectives: This study was carried out to evaluate the quality of the peels of various Citrus species. Method: The contents of hesperidin from fruit peels used as Citri Pericarpium such as C. natsudaidai, C. grandis, C. unshiu, and C. sunki, were analyzed by HP-TLC, HPLC, and essential oils of those were analyzed by GC/MS. Results: HPLC analysis showed that the hesperidin from the peel of C. unshiu and C. reticulata was satisfied the standard of Korean Pharmacopoeia. The essential oil was analyzed by GC/MS. As a result, limonene, furfural, 5-methyl-2-furfural, linalool oxide(cis), linalool oxide(trans), terpinen-4-ol, $(-)-{\alpha}$-terpineol, germacrene D, 4-methyl-2,6-di-tert-butylphenol was detected in all 4 kinds of Citrus species. Conclusions: As a result of chemotaxonomical similarity analysis with essential oils, the peels of C. natsudaidai and C. grandis are closely related, while C. unshiu is distantly related to the others.

• Korean Journal of Food Science and Technology
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• v.46 no.4
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• pp.465-469
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• 2014

The extraction of flavanones such as naringin, narirutin, naringenin, hesperidin, and hesperetin from grapefruit peels was performed using subcritical water extraction (SWE), hot water extraction, and conventional methods such as methanol and ethanol extraction. We analyzed the total flavanone content using high-performance liquid chromatography (HPLC) for each extracting method. Among the three methods, SWE was the optimal method with optimal operating conditions of $170^{\circ}C$ temperature and 10 min operating time. The maximum total flavanone extracted was $86.539{\pm}3.52mg/g$ grapefruit peels. Moreover, we treated the extracts with 60% ${\beta}$-cyclodextrin and then analyzed the surface structure of the encapsulated compounds by field emission-scanning electron microscopy (FE-SEM). The results indicated that the encapsulation in ${\beta}$-cyclodextrin improved solubilization, and the inclusion complex could serve as food supplements.