Judul: Detection of Vegetable Oil Adulteration with Lard Oil Based on Color Profile, Infrared Radiation Absorption and Chemometrics
Abstrak: Vegetable oils in most case are adulterated with animal fat, mainly lard to attain desired characteristics. The escalation awareness of halal and vegan diet encourages the need for rapid adulteration detection in Indonesia. This study aims to identify the presence of lard adulteration based on the infrared absorption and color profile using Fourier Transform Infrared Spectroscopy and Chromameter. This study consisted of five stages: sample preparation, spectra optimization, infrared absorption and color profile analysis, and data analysis. Data analysis was carried out using Principal Component Analysis and Orthogonal Project to Latent Structures Discriminant Analysis to obtain discriminant factors. The study was conducted on six vegetable oils, namely olive, soybean, sesame, sunflower, coconut, and corn oil, spiked with lard at a concentration of 1% to 100%. Results showed the discriminant functional groups were secondary alcohol, ester, alkene alkane, and carboxylic groups. Adulteration can be identified based on the color profile determined from the mapping of samples treated separately from the pure samples. Adulteration of lard can be identified by the differences in the composition of fatty acids, glycerides, and color profile. Detection of adulteration based on the infrared absorption profile and color profile gives sensitive results at concentration below 40%.
Keyword: adulteration, Chromameter, FTIR, lard oil, multivariate analysis

Judul: Pendugaan Kandungan Kimia Minyak Goreng Menggunakan Near Infrared Spectroscopy
Abstrak: Indonesia menjadi penghasil minyak kelapa sawit terbesar yang berdampak pada perkembangan industri makanan dan rumah tangga. Tingginya kebutuhan akan minyak goreng tidak diimbangi dengan harga yang terjangkau, sehingga pelaku usaha menggunakan minyak goreng berulang kali bahkan hingga menghitam menyebabkan penurunan mutu. Monitoring penurunan mutu minyak goreng pada umumnya dilakukan dengan metode kimia. Metode kimia dianggap kurang praktis, sehingga diperlukan metode alternatif. Near Infrared Spectroscopy (NIRS) dapat menjadi metode alternatif yang lebih cepat dan akurat untuk menguji penurunan mutu minyak goreng dibandingkan dengan metode kimia. Penelitian ini bertujuan untuk memonitoring penurunan mutu minyak goreng yang digunakan berulang menggunakan metode NIRS dengan menentukan pengolahan data spektrum dan jumlah faktor utama terbaik dengan metode Partial Least Square (PLS) pada panjang gelombang 1000 – 2500 nm. Sampel minyak goreng dihasilkan dari 0 – 15 kali proses penggorengan sehingga terdapat variasi mutu pada setiap tahap penggorengan dengan jumlah sampel keseluruhan sebanyak 32 sampel. Bilangan peroksida dan kadar asam lemak bebas dievaluasi sebagai parameter kandungan kimia utama. Data spektrum diolah menggunakan metode normalisasi, Standard Normal Variative (SNV), Multiplicative Scatter Correction (MSC), dan Detrending, kemudian dikalibrasi dengan data kimia menggunakan Partial Least Square (PLS). Nilai terbaik ditentukan berdasarkan pada nilai koefisien korelasi (r), Standard Error of Calibration (SEC) dan Standard Error of Prediction (SEP). Pendugaan terbaik untuk bilangan peroksida menggunakan pretreatment Detrending dengan faktor 7 diperoleh nilai r 0,93, SEC 0,17%, dan SEP 0,16%. Sedangkan untuk pendugaan terbaik kadar asam lemak bebas menggunakan spektrum original dengan faktor 8 diperoleh nilai r 0,94, SEC 0,016%, dan SEP 0,019%. Hasil ini menunjukkan bahwa Near Infrared Spectroscopy (NIRS) dapat digunakan untuk memonitoring penurunan mutu minyak goreng., Indonesia is the largest producer of palm oil which has an impact on the development of the food and household industries. The high need of cooking oil is not followed by an affordable price. Thus, industries use cooking oil repeatedly, even it turns black, causing a decrease in quality. Cooking oil quality monitoring is generally carried out by chemical methods. Chemical methods are considered less practical, so an alternative method is needed. Near Infrared Spectroscopy (NIRS) can be an alternative method that is faster and more accurate to monitor deterioration of cooking oil quality compared to chemical methods. This study aims to assess NIR spectroscopy for monitoring the quality change of cooking oil that is used repeatly, especially to determine the best spectrum data processing and the number of main factors of partial least square (PLS) for prediction the quality cooking oil. Cooking oil samples were produced from 0 – 15 times in the frying process so that there were variations in quality at each stage of frying with a total sample of 32 samples. Transflectance of cooking oil was measured by FT NIR spectrometer at wavelength of 1000 – 2500 nm. Peroxide number and free fatty acid content as the main chemical content of cooking oil parameters were determined by chemical method. Absorbance spectrum data are processed using some spectra pretreatments such as normalization, Standard Normal Variative (SNV), Multiplicative Scatter Correction (MSC), and Detrending. The best value is determined based on the value of the
Keyword: cooking oil, free fatty acid, NIR, peroxide number, PLS

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf