Judul: Sensory Optimization of Chocolate Bar Products from XYZ Industry using CATA, RATA, and JAR Methods
Abstrak: Indonesia is a major player in the global cocoa production and export industry, yet domestic chocolate consumption remains low, averaging only 0.10 kg per person per year compared to higher consumption rates in Europe. This low consumption is attributed to subpar chocolate products and the consumer perception that chocolate is an unhealthy food associated with obesity. XYZ industry, based in Magelang Regency, Central Java, aims to support local cocoa farmers and produce healthier, vegan chocolate bars with functional benefits. However, their current chocolate bar products do not consistently meet consumer taste preferences, despite their health advantages. Sensory evaluation was conducted on 12 chocolate bar products using Check-All-That-Apply (CATA), Rate-All-That-Apply (RATA), and Just-About-Right (JAR) methods to understand consumer perceptions and preferences. CATA identified Solid Energy Chocolate as the ideal product due to its nutty and cereal attributes. RATA analysis provided detailed sensory profiles, revealing that Sea Salt & Almond, Lactation Chocolate, and Solid Energy were most preferred by consumers. JAR method results indicated that the majority of attributes in the Solid Energy Chocolate variant were considered “too little,” but the results were inconclusive due to panelist misinterpretation of intensity scales. Sensory optimization needs to be performed on 6 chocolate bar variants that has the percentage of consumer’s satisfaction low, to better meet consumer preferences., Indonesia adalah pemain utama dalam industri produksi dan ekspor kakao global, namun konsumsi cokelat domestik tetap rendah, rata-rata hanya 0.10 kg per orang per tahun dibandingkan dengan tingkat konsumsi yang lebih tinggi di Eropa. Konsumsi yang rendah ini disebabkan oleh produk cokelat yang kurang memadai dan persepsi konsumen bahwa cokelat adalah makanan tidak sehat yang berkaitan dengan obesitas. Industri XYZ, yang berbasis di Kabupaten Magelang, Jawa Tengah, bertujuan untuk mendukung petani kakao lokal dan memproduksi cokelat batangan yang lebih sehat, vegan, dan memberikan manfaat fungsional. Namun, produk cokelat batangan mereka saat ini tidak secara konsisten memenuhi preferensi rasa konsumen, meskipun memiliki keunggulan kesehatan. Evaluasi sensori dilakukan pada 12 produk cokelat batangan menggunakan metode Check-All-That-Apply (CATA), Rate-All-That-Apply (RATA), dan Just-About-Right (JAR) untuk memahami persepsi dan preferensi konsumen. CATA mengidentifikasi Solid Energy Chocolate sebagai produk ideal karena atributnya yang nutty dan sereal. Analisis RATA memberikan profil sensori yang mendetail, mengungkapkan bahwa varian Sea Salt & Almond, Lactation Chocolate, dan Solid Energy adalah yang paling disukai oleh konsumen. Hasil metode JAR menunjukkan bahwa mayoritas atribut pada varian Solid Energy Chocolate dianggap “terlalu sedikit,” namun hasil ini tidak konklusif karena kesalahan interpretasi intensitas oleh panelis. Optimalisasi sensori dirasa perlu dilakukan pada 6 varian cokelat batangan yang memiliki persentase kepuasan konsumen rendah, agar dapat memenuhi preferensi konsumen.
Keyword: sensory evaluation, CATA, RATA, JAR, Chocolate bar, Check-all-that-apply, Rate-all-that-apply, Just-about-right

Judul: Pengembangan Minuman Cokelat Instan Komersial Menggunakan Atribut Sensori Terpilih Berdasarkan Preferensi Konsumen
Abstrak: Cacao is one of important commodity in Indonesia. Based on statistical data on 2020, export value of cacao beans reaches US$ 1,22 billion. Application of cacao beans is used as raw material for making chocolate drink. Some industries in Indonesia are developing instant commercial chocolate drink. Sensory evaluation is a key point for developing new product to meet with consumer criteria. Liking is not enough to evaluate sensory quality of the product. However, consumer satisfaction must be considered in sensory evaluation so that the product will be purchased continuously by customer. This research is the first step in development of instant commercial chocolate drink. Objective of this study are identifying consumer preference about instant chocolate drink product from market, identifying sensory attributes that are able to consumer satisfaction and their combination to improve the reach and consumer frequency. Relationship between sensory appeals and consumer satisfaction was identified by survey method integrated with structural equation model (SEM). Focus group discussion (FGD) method was utilized to identify sensory attributes of commercial instan chocolate drink. Then, Kano method is used to categorize the selected sensory attributes based on consumer satisfaction. Total unduplicated reach and frequency (TURF) method is used then to evaluate selected sensory attributes based on reach and frequency. Sensory attributes appeal affected consumer satisfaction of commercial instant chocolate drink with linear coefficient value 0,7. Better performance of sensory attributes increased consumer satisfaction. Sensory attributes of commercial instant chocolate drink consist of six groups including taste, flavor, aroma, texture, aftertaste and color. Based on Kano categorization, creamy and dark chocolate color were included in attractive category, chocolate attributes (color, aroma, flavor) were include in one-dimensional category, and sweet was included in must-be category. Furthermore, the combination of several selected attributes can be an alternative to maximize the production line. The combination of two variants flavor such as original chocolate flavor and chocolate with almonds flavor can be an alternative to reach 100% of the target market.
Keyword: chocolate drink, Kano, SEM, TURF, sensory evaluation

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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