The purpose of this study was to investigate the properties of starch in potatoes (Solanum tuberosum cv. Agria) after being treated with pulsed electric fields (PEF). Potatoes were treated at 50 and 150 kJ/kg specific energies with various electric field strengths of 0, 0.5, 0.7, 0.9 and 1.1 kV/cm. Distilled water was used as the processing medium. Starches were isolated from potato tissue and from the PEF processing medium. To assess the starch properties, various methods were used, i.e., the birefringence capability using a polarised light microscopy, gelatinisation behaviour using hot-stage light microscopy and differential scanning calorimetry (DSC), thermal stability using thermogravimetry (TGA), enzyme susceptibility towards α-amylase and the extent of starch hydrolysis under in vitro simulated human digestion conditions. The findings showed that PEF did not change the properties of starch inside the potatoes, but it narrowed the temperature range of gelatinisation and reduced the digestibility of starch collected in the processing medium. Therefore, this study confirms that, when used as a processing aid for potato, PEF does not result in detrimental effects on the properties of potato starch.

This study was performed to assess the heat resistance of spores of Bacillus species in batch and continuous heating systems under commercial sterilisation conditions. Spores of thermophilic Bacillus smithii and mesophilic Bacillus amyloliquefaciens were found to be highly heat resistant in the batch system. They were able to withstand typical sterilisation temperatures. B. amyloliquefaciens showed tailing in the batch system and, before the onset of the tailing, a higher inactivation rate than in the continuous system at low temperatures. The reason for the tailing might be the presence of spore aggregates which are disrupted in the continuous system.

The current research aimed to investigate the effect of pulsed electric fields (1 kV/cm; 50 and 150 kJ/kg) followed by blanching (3 min., 100 °C) on the colour development of potato slices during frying on a kinetic basis. Four potato cultivars ‘Crop77’, ‘Moonlight’, ‘Nadine’, and ‘Russet Burbank’ with different content of glucose and amino acids were used. Lightness (L* values from colorimeter measurement) was used as a parameter to assess the colour development during frying. The implementation of PEF and blanching as sequential pre-treatment prior to frying for all potato cultivars was found effective in improving their lightness in the fried products. PEF pre-treatment did not change the kinetics of L* reduction during frying (between 150 and 190 °C) which followed first-order reaction kinetics. The estimated reaction rate constant (k) and activation energy (Ea based on Arrhenius equation) for non-PEF and PEF-treated samples were cultivar dependent. The estimated Ea values during the frying of PEF-treated ‘Russet Burbank’ and ‘Crop77’ were significantly (p < 0.05) lower (up to 30%) than their non-PEF counterparts, indicating that the change in k value of L* became less temperature dependence during frying. This kinetic study is valuable to aid the optimisation of frying condition in deep-fried potato industries when PEF technology is implemented.

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Program Studi Teknologi Pangan, Fakultas Peternakan dan Pertanian, Universitas Diponegoro, Semarang *Korespondensi dengan penulis (amalinanoors@gmail.com) Artikel ini dikirim pada tanggal 15 Januari 2017 dan dinyatakan diterima tanggal 18 Juni 2017. Artikel ini juga dipublikasi secara online melalui www.jatp.ift.or.id. Hak cipta dilindungi undang-undang. Dilarang diperbanyak untuk tujuan komersial. Diproduksi oleh Indonesian Food Technologists® ©2017 AbstrakPenelitian ini bertujuan untuk mengetahui sifat fisik edible film dari tepung pati umbi garut dan minyak sawit dengan perbedaan konsentrasi antar keduanya, serta mengetahui konsentrasi yang tepat antara beberapa perlakuan yang menghasilkan edible film terbaik. Penelitian ini dirancang secara acak lengkap (RAL) dengan dua faktor. Faktor I adalah konsentrasi tepung pati umbi garut (3%, 4%, dan 5% b/v) dan faktor II adalah penambahan konsentrasi minyak sawit (0%, 0,3%, dan 0,6% v/v). Setiap perlakuan dilakukan sebanyak 3 kali ulangan dengan parameter yang diujikan yaitu berupa ketebalan, water vapor transmission rate, tensile strength, dan persentase pemanjangan. Nilai water vapor transmission rate terbaik yaitu sebesar 10,691 g/m 2 /jam dengan formula konsentrasi tepung pati umbi garut 5% (b/v) dan konsentrasi minyak sawit 0,6% (v/v). Pada nilai water vapor transmission rate ini, nilai ketebalan yang diperoleh yaitu 0,1134 mm, tensile strength 2,8 N/mm 2 dan presentase pemanjangan 43%. Dalam menentukan nilai, tepung pati umbi garut dan minyak berinteraksi (P<0,05) pada nilai ketebalan, water vapor transmission rate, dan persentase pemanjangan namun tidak berinteraksi (P>0,05) dalam menentukan nilai tensile strength.Kata kunci: sifat fisik, edible film, umbi garut, minyak sawit (3%, 4%, and 5% b/v) and the second was the concentration of palm oil (0%, 0,3%, and 0,6% v/v) Abstract The purpose of this research is to determine the physical properties of edible film from arrowroot starch flour and palm oil with difference concentration between both of them, and also to investigate the right concentration among some treatment which have best result. This research used Completely Randomized (CRD) is arranged with two factors. The first factor was the concentration of arrowroot stratch flour

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dengan penulis (anggienjie@gmail.com) Artikel ini dikirim pada tanggal 2 Juni 2016 dan dinyatakan diterima tanggal 4 November 2016. Artikel ini juga dipublikasi secara online melalui www.jatp.ift.or.id. Hak cipta dilindungi undang-undang. Dilarang diperbanyak untuk tujuan komersial. Diproduksi oleh Indonesian Food Technologists® ©2017 AbstrakPenelitian bertujuan untuk mendapatkan roti yang mempunyai sifat fisik yang lebih baik (warna lebih coklat, tekstur lembut dan empuk, kandungan air optimum, dan ɑ w relatif rendah). Bahan yang digunakan dalam pembuatan roti manis yaitu tepung terigu protein tinggi 250 g; ragi 5,5 g; air es 50 ml; susu UHT 65 ml; susu bubuk 12,5 g; bread improver 1,5 g; kuning telur 2 buah; mentega 50 g; garam setengah sendok teh; sukrosa 50 g; fruktosa 50 g; madu 50 g; dan glukosa 50 g. Roti dibuat dengan empat jenis gula sebagai perlakuan yaitu sukrosa (T0), glukosa (T1), fruktosa (T2) dan madu (T3). Alat yang digunakan untuk uji warna (kecerahan) adalah colorimeter, alat uji tekstur (daya iris) dengan universal texture analyzer, alat uji kadar air dengan metode gravimetri, dan alat uji ɑ w dengan ɑ w -meter dan didapatkan hasil yaitu 18,275%; 0,8016; 0,9581 N/mm 2 ; 70,6 (sukrosa); 18,652%; 0,7962; 0,9577 N/mm 2 ; 55,5 (glukosa); 23,084%; 0,8358; 1,047 N/mm 2 ; 58,4 (fruktosa); 22,941%; 0,8736; 0,7035 N/mm 2 ; 67,1 (madu). Fruktosa dan madu menghasilkan kadar air yang tinggi. Sukrosa dan glukosa menghasilkan aktivitas air yang rendah. Madu menghasilkan tekstur paling empuk. Fruktosa dan glukosa menghasilkan warna paling gelap.Kata kunci: roti manis, sukrosa, glukosa, fruktosa, madu. AbstractThe

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