In this research, local citrus fruits, namely Garut citrus, were analyzed for electrical properties related to physicochemical properties. Electrical measurement on fruit was done by using low alternating current with a frequency varying from 50 Hz to 1 MHz. The fruits are placed between two plate electrodes and treated as dielectric material. Electrical parameters per unit of weight were used in this study to compensate variations in weight. Electrical impedance, resistance, and reactance per weight of citrus fruits will decrease if the frequency is increased. Electrical circuit models have been constructed to describe the internal conditions of citrus fruits. To indicate the fruit maturity, the physicochemical properties were used, i.e., firmness, total soluble solids, pH, and hydrogen ion concentration. The value of resistance, impedance, and reactance per weight declined during citrus fruits maturation. The correlations between electrical and physicochemical properties are investigated too. The highest consistency of correlations happens at a frequency of 1 MHz. Based on the model of an electrical circuit, the highest value of electrical resistance is outer shell and the lowest is seed. And then, the highest value of electrical capacitance is albedo and the lowest is segment. Resistance values of the parts of citrus fruits, i.e., seed, segment, segment wall, and outer shell, were decreased during maturation. While capacitance value of segment, albedo, and flavedo were increased.

Selain itu, JTEP juga telah terdaftar pada Crossref dan telah memiliki Digital Object Identifier (DOI) dan telah terindeks pada ISJD, IPI, Google Scholar dan DOAJ. Mulai edisi ini redaksi memandang perlu untuk meningkatkan nomor penerbitan dari dua menjadi tiga kali setahun yaitu bulan April, Agustus dan Desember berisi 12 naskah untuk setiap nomornya. Hal ini dimaksudkan untuk mengurangi masa tunggu dengan tidak menurunkan kualitas naskah yang dipublikasikan. Jurnal berkala ilmiah ini berkiprah dalam pengembangan ilmu keteknikan untuk pertanian tropika dan lingkungan hayati. Penulis makalah tidak dibatasi pada anggota PERTETA tetapi terbuka bagi masyarakat umum. Lingkup makalah, antara lain: teknik sumberdaya lahan dan air, alat dan mesin budidaya pertanian, lingkungan dan bangunan pertanian, energi alternatif dan elektrifikasi, ergonomika dan elektronika pertanian, teknik pengolahan pangan dan hasil pertanian, manajemen dan sistem informasi pertanian. Makalah dikelompokkan dalam invited paper yang menyajikan isu aktual nasional dan internasional, review perkembangan penelitian, atau penerapan ilmu dan teknologi, technical paper hasil penelitian, penerapan, atau diseminasi, serta research methodology berkaitan pengembangan modul, metode, prosedur, program aplikasi, dan lain sebagainya. Penulisan naskah harus mengikuti panduan penulisan seperti tercantum pada website dan naskah dikirim secara elektronik (online submission) melalui http://journal.ipb.ac.id/index.php/jtep.

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Conventional production process of gambir often produces gambir with low content of catechin. Engineering of production processes of gambir leaves to produce gambir powder has been developed by previous researchers. The objective of this study was to develop a calibration model to predict the content of catechin in gambir powder from dried gambir leaves quickly using FT-NIR PLS model. Reflectance spectra of gambir powder from dried gambir leaves obtained at a wavelength of 1000 to 2500 nm. Spectra pre-processing treatment method used was a combination between normalization between 0 and 1 (n01) method and first derivative Savitzky-Golay 9 points (dg1). The result showed that correlation coefficient and standard error of prediction (SEP) were 0.99 and 2.10 % respectively, obtained when used 6 factors of partial least square (PLS). Calibration model developed has shown higher accuracy and precision to predict catechin content of gambir powder from dried gambir leaves.

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