第２０回生物資源環境科学府賞受賞者

・Mohamed Zakaria Elhussiny Elkhawaga （博士後期課程）
資源生物科学専攻

家畜生体機構学分野「Studies on the elucidation of central functions of taurine to regulate bodytemperature, food intake and stress response in neonatal chicks」

・Ata Aditya Wardana （博士後期課程）
環境農学専攻農産食料流通工学分野「Development of chitosan-based nanocomposite enriched with essential oil
as antifungal coating for fresh fruit application」

Name：モハメド ザカリヤ エルホセーニ エルハワーガ
Mohamed Zakaria Elhussiny Elkhawaga

Title：Studies on the elucidation of central functions of taurine to regulate bodytemperature, food intake and stress response in neonatal chicks(ニワトリヒナの体温、摂食およびストレス応答を制御するタウリンの中枢機能の解明に関する研究)
Thesis Abstract

Environmental stressors in poultry such as heat stress, social isolation stress, cold stress, etc. negatively
affect poultry performance, health and welfare. These stressors cause physiological alterations, behavioral
changes, reduction in production and high mortality. Amino acids are getting attention nowadays as anovel approach to mitigate stress responses in poultry. In this study, a novel role and functional mechanismof taurine have been investigated to mitigate stress response in neonatal chicks.
My research finding revealed that central taurine induced dose-dependent hypothermia and reduced
food intake in neonatal chicks under control thermoneutral temperature. Further, it was found that γaminobutyric acid A (GABAA) receptor mediated taurine-induced hypothermia. In addition, central taurine
afforded thermotolerance with rapid initiation of heat dissipation behaviors; namely, panting and wing
dropping, compared with control birds along with the modification of mitochondrial thermogenic gene
expressions. Furthermore, central taurine attenuated hyperthermia and isolation stress behaviors in chicks
through inducing sedative and hypnotic effects. Moreover, norepinephrine and serotonin were found to
mediate taurine-induced hypothermia; however, serotonin alone may be linked with taurine-induced
anorexia. Furthermore, changes in several amino acid concentrations by central injection of taurine further
suggest that amino acid metabolism may change to contribute to the central thermoregulatory and stressattenuating functions of taurine.
In conclusion, the present study revealed a novel nutritional factor, taurine to alleviate heat stress andisolation-stress response in chicks. Several mechanisms have been investigated to reveal the regulatory
functions of taurine in the brain including the mechanisms of GABAA receptor, amino acids andmonoamines. Furthermore, the central regulatory mechanisms of taurine provided a better understandingof thermoregulation, appetite regulation and stress response, which has far-reaching implications in a
multitude of species and biological contexts.

Development of chitosan-based nanocomposite
enriched with essential oil as antifungal coating for
fresh fruit application
Ata Aditya Wardana

SUMMARY
Edible packaging (coatings and films) has been used to improve the shelf life of fresh
fruit produce. The preparation process for edible packaging depends on the properties of theingredient and the application end use. The objective of this study were to 1) develop antifungal
nanocomposite coating formulated from chitosan (Chi), Indonesia-originated essential oil, andnanoparticles; 2) characterize the functional properties of the coating film. This was done byoptimizing the raw material dosage selection, and blending sequence.
In the first work, the properties of an antifungal coating film made from Chi combinedwith zinc oxide nanoparticles (ZNPs) and Indonesian sandalwood essential oil (SEO) wereinvestigated. Incorporation of 0.5% SEO or 0.025% ZNPs plus 0.5% SEO into 0.8% Chi
coating solution showed outstanding effects on the inhibition of both mycelium growth andspore germination of Penicillium italicum. The antifungal mechanism was explained bymeasuring the loss of membrane integrity of spores. The antifungal effectiveness was confirmed
in vivo by carrying out tests on tangerine fruit. The biocompatibility of these coatings wasanalyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, atomicforce microscopy, and fluorescence microscopy. Significant increases in pH, appearance
viscosity, and transparency and a decrease in light transmittance were found with 0.8% Chi plus
0.025% ZNPs and 0.5% SEO compared with the control. Chi films incorporating SEO andZNPs can be used as an edible film and coating to reduce chemical use.
Further work, a novel formulation of composite coating comprising 0.8% Chi
incorporating 0.025% copper(II) oxide nanoparticles (CuO) and 0.5% Indonesian cedarwood
essential oil (CEO) was fabricated by casting method. FTIR, CLSM, and SEM analyses wereemployed to characterize the biocompatibility of each formulation. Additionally, the physicochemically properties of the composite coatings were characterized. The colour (L*), lighttransmission, zeta potential, and roughness of Chi were significantly (P < 0.05) alterednegatively by the presence of CuO or CEO; the colour (a*, b*, and ∆E), apparent viscosity, andtransparency also changed positively as a consequence of CuO and CEO incorporation. The
antifungal features of a pure Chi coating against Penicillium italicum and Penicillium digitatum
were improved synergistically by CuO and CEO, confirmed by in vitro and in vivo assays.
Composite coatings obtained in this work may have potential applications for active primary
food packaging, particularly for fresh postharvest commodities.
Lastly, a novel composite edible coating film was developed from 0.8% Chi and 0.5%
sandalwood oil (SEO). Cellulose nanofibers (CNFs) were used as a stabilizer agent of oil-inwater Pickering emulsion. We found four typical groups of CNF level-dependent emulsion
stabilization, including (1) unstable emulsion in the absence of CNFs; (2) unstable emulsion(0.006–0.21% CNFs); (3) stable emulsion (0.24–0.31% CNFs); and (4) regular emulsion withthe addition of surfactant. Confocal laser scanning microscopy was performed to reveal thecharacteristics of droplet diameter and morphology. Antifungal tests against Botrytis cinerea

and Penicillium digitatum, between emulsion coating stabilized with CNFs (Chi/SEO Pickering)and Chi or Chi/SEO was tested. The effective concentration of CNFs (0.24%) may improve theperformance of Chi coating and maintain Chi/SEO antifungal activity synergistically confirmedwith a series of assays (in vitro, in vivo, and membrane integrity changes). The incorporationof CNFs contributed to improve the functional properties of Chi and SEO-loaded Chi including
light transmission at UV and visible light wavelengths and tensile strength. AFM and SEM
were employed to characterize the biocompatibility of each coating film formulation.
Emulsion-CNF stabilized coating may have potential applications for active coating for freshfruit commodities.
In summary, this doctoral dissertation proposed new functional coating materials as analternative to plastic packaging by developing chitosan-based agents that were effective inpreserving the quality of fresh fruits and preventing spoilage through its antimicrobial effect.