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All Journal Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Jurnal Teknologi Pertanian Andalas
Sri Rahayoe
Universitas Gadjah Mada
Agriculture, Biological Sciences & Forestry Computer Science & IT Engineering

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Physical Characteristic of Heat Resistant Chocolate Formulated with Konjac Glucomannan and Xanthan Gum-Based Hydrogel at Various Fat Content during Period of Crystal Growth (Maturation) Arifin Dwi Saputro; Mira Aprilia Nur Fadilah; Samuel Keegen Bangun; Sri Rahayoe; Joko Nugroho Wahyu Karyadi; Arima Diah Setiowati
Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Vol 11, No 4 (2022): Desember 2022
Publisher : The University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtep-l.v11i4.658-670

Abstract

Indirect addition of water into chocolate may form secondary sugar networks. This condition creates an increased melting temperature of chocolate. The purpose of this study was to increase the melting point of premium couverture chocolate without addition of fat/oil from other sources.  Chocolate was formulated with coconut/palm sugar as sweetener at various fat levels (32%, 34%, and 36%).  Aside from this, Konjac glucomannan and Xanthan gum-based hydrogel with a concentration of 3%, 5%, and 7% was added. Characterization of chocolate quality parameters with the addition of konjac glucomannan-based hydrogel (CKG) and xanthan gum-based hydrogel (CXG) was carried out. Moisture content, melting point, hardness, particle size and brown color analyses were carried out at intervals of 1, 5, 9 days of maturation (crystal growth period). The results showed that the addition of hydrogel influenced the melting point and hardness.  As the period of crystal growth (maturation) increased, the melting point and hardness of the chocolate also increased. Keywords:   Heat Resistant Chocolate, Hydrogel, Konjac Glucomannan, Palm Sugar, Xanthan Gum
MATHEMATICAL MODEL OF PHYSICAL PROPERTIES CHANGE OF COCONUT SAP IN THE VACUUM EVAPORATOR Febryan Kusuma Wisnu; Sri Rahayoe; Rizza Wijaya; Mareli Telaumbanua; Agus Haryanto
Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Vol 10, No 2 (2021): Juni
Publisher : The University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtep-l.v10i2.252-262

Abstract

The potential of brown sugar as a substitute for granulated sugar is enormous considering the abundant coconut sap production. However, the quantity of brown sugar production through the traditional method is one of the main obstacles. This study used a vacuum evaporator that emphasizes the hygienic and effective mass production of brown sugar. For this reason, it is necessary to approach changes in the physical properties of sap juice during the cooking process. This knowledge is indispensable in the cooking process, which involves the proper evaporation and crystallization of brown sugar. This research is devoted to determining the viscosity, density, and dissolved solids expressed in Brix and proposes a mathematical model to predict the physical properties during the evaporation process of brown sugar as a function of the initial concentration the solution before proceeding to the crystallization process. Results confirm that the prediction model for Brix is Cθ=(Co–Ce)·exp(0.0067·t)+Ce, the model for viscosity µθ=µo·exp(0.011·t), and ρө=(0.44996·t)+ρ0 for the density prediction model. The resulted mathematical model can accurately predict the rate of change in coconut sap's physical properties, indicated by the high coefficient of determination (R2). Keywords : brix, brown sugar, density, vacuum evaporator, viscosity
SIFAT FISIK DAN MEKANIK KEMASAN TABLEWARE DARI KOMPOSIT AMPAS TEH HITAM DAN TEPUNG TAPIOKA Riel Jeremy Jordan Umboh; Yudi Pranoto; Sri Rahayoe
Jurnal Teknologi Pertanian Andalas Vol 27, No 1 (2023)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jtpa.27.1.65-75.2023

Abstract

Classification of Freshness Levels and Prediction of Changes in Evolution of NH3 and H2S Gases from Chicken Meat during Storage at Room Temperature Pramilih Nastiti; Nursigit Bintoro; Joko Karyadi; Sri Rahayoe; Darmawan Nugroho
Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Vol 11, No 1 (2022): March
Publisher : The University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtep-l.v11i1.90-98

Abstract

Chicken meat has a high nutrient content. However, its quality is easy to be degraded. The degradation is normally characterized by the formation of metabolite gases (NH3 and H2S) as deterioration indicators. Sensors detect phenomena better than human senses. This study aimed to classify meat quality based on gas formation during meat storage. In addition, a kinetics model of gas changes was determined. The gases were detected using a set of equipment consisting of Raspberry Pi and Metal-Oxide-Semiconductor (MOS) gas sensors. Samples were put in a 10 x 10 x 10 (cm) black container. MOS sensors were put inside the box to detect the gases at room temperature for 24 hours, with data collection being recorded every hour. Obtained data were then analyzed using Principle Component Analysis (PCA) for quality classification. The study showed that the quality of chicken meat was classified into three groups with a total variance of more than 95%. PC1 explained 88.2%, and PC2 explained 9.0%. The constant rate of H2S and NH3 changes followed the first-order kinetics with a constant rate of 0.2641 and 0.2925, respectively. The equation for H2S and NH3 changes were Ct=1.70 e0.2641 t and Ct=1.00 e0.2925 t, respectively. Keywords: Chicken meat, Freshness, H2S gas, NH3 gas, Sensor
The Kinetics of Ethanol Volume Change With Variation of Input Volume and Heating Temperature in The Re-Distillation Process of Glucomannan Extraction Residue Using Batch Distillator Saut Edo Riko Manurung; Rizky Qhasim Pratama; Sri Rahayoe; Joko Nugroho W. K; Febryan Kusuma Wisnu
Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Vol 11, No 1 (2022): March
Publisher : The University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtep-l.v11i1.161-173

Abstract

Ethanol is commonly used as a solvent in extracting glucomannan from Porang. However, the extraction process often leaves ethanol. The remaining ethanol can be re-distilled to save the use of it. The remaining ethanol is used in the re-distillation process with input volumes of 50L and 100L with variations in heating temperatures of 80°C, 85°C, and 90°C. This study aimed to analyze the effect of the ethanol input volume and temperature on the output volume of re-distilled ethanol and determine the constant change in volume of re-distilled ethanol using kinetics and Arrhenius equations. The results showed that the input volume and heating temperature variation differed significantly from the ethanol output volume. The k value changes in the ethanol output volume from re-distillation with an input volume of 50L and a temperature variation of 80°C, 85°C, and 90°C respectively were 0.0016, 0.0023, and 0.0027 L/min, while the input volume of 100L was 0.0009, 0.001, and 0.0014 L/min. The results of the k value as a function of temperature using the Arrhenius equation showed that the re-distillation process with an input volume of 50L and 100L produces activation energy (Ea) of 55.83 kJ/mol and 46.94 kJ/mol, while the collision frequency value (A) of 3.03x105/min and 7.7x103/min.Keywords: Distillation, ethanol, glucomannan, arrhenius model, re-distillation
Effect of Microclimate Temperature and Relative Humidity on the Postharvest Quality of Coconut Sap and Sugar Sri Rahayoe; Hilda Maya Sintia Dewi; Andri Prima Nugroho; Arifin Dwi Saputro; Ngadisih Ngadisih
Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Vol. 14 No. 3 (2025): June 2025
Publisher : The University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtep-l.v14i3.899-910

Abstract

Coconut sap, increasingly recognized as a functional sweetener, is highly perishable and influenced by environmental conditions during postharvest handling, yet the specific impacts of microclimatic variables such as temperature and relative humidity (RH) on sap and sugar quality remain inadequately studied. This research investigates the effects of RH and temperature on key physicochemical parameters of coconut sap—pH, Brix, and density—and evaluates their influence on coconut sugar quality, focusing on moisture, ash content, and color. Sap was collected biweekly in Central Java over a five-week period and analyzed in conjunction with environmental data recorded using an IoT-based weather station. Increased RH was significantly associated with decreased sap pH (r = –0.482, p = 0.007) and showed a weak negative correlation with Brix. Density remained stable across varying RH levels. Although temperature showed visual trends in sap quality parameters, statistical analysis did not reveal significant correlations, likely due to the narrow temperature range during the observation period. Throughout sugar processing, TSS increased consistently across boiling, saturation, and oversaturation stages. Final sugar blocks maintained stable moisture (6–8%) and ash content (1.8–2.2%), with color variations reflecting Maillard and caramelization reactions. Maintaining RH below 85% is recommended to preserve sap quality and product consistency. Keywords: Coconut sap, Coconut sugar, Postharvest quality, Relative humidity, Temperature.
Processing and Quality of Crystalized Palm Sugar in Indonesia: A Review Hary Kurniawan; Sri Rahayoe; Hanim Zuhrotul Amnah
Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) Vol. 14 No. 4 (2025): August 2025
Publisher : The University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtepl.v14i4.1517-1533

Abstract

Crystalized palm sugar derived from coconut and arenga palm sap has high-value for industrial products. The crystalized sugar offers several advantages over molded palm sugar, including a longer shelf life, lower glycemic index, and greater flexibility in its applications. However, palm sugar production in Indonesia is still predominantly carried out using traditional methods, which are inefficient in terms of quality control and production capacity. This review explores various aspects of palm sugar processing and quality in Indonesia, including raw materials, production processes, quality determinants, as well as challenges and development prospects. Key factors influencing product quality include the quality of raw materials, cooking techniques, drying methods, and proper storage practices. Uncontrolled fermentation of sap can hinder crystallization, while high moisture content may cause clumping and reduce product stability. To enhance global competitiveness, palm sugar must meet both the national and international certifications. The main challenges in this industry include the lack of Good Manufacturing Practices (GMP), limited adoption of modern processing technologies, and inconsistency in product quality. Quality improvement efforts through artisan training, production modernization, and supply chain strengthening are essential to ensuring that Indonesian palm sugar can compete in international markets. With proper strategies, palm sugar holds promising potential as a flagship export commodity from Indonesia.
Co-Authors Agus Haryanto Andri Prima Nugroho Arifin Dwi Saputro, Arifin Dwi Arima Diah Setiowati Darmawan Nugroho Febryan Kusuma Wisnu Hanim Zuhrotul Amnah Hilda Maya Sintia Dewi Joko Karyadi Joko Nugroho W. K Joko Nugroho Wahyu Karyadi Kurniawan, Hary Mareli Telaumbanua Mira Aprilia Nur Fadilah Ngadisih Ngadisih Nursigit Bintoro Pramilih Nastiti Riel J. J Umboh Rizky Qhasim Pratama Rizza Wijaya Samuel Keegen Bangun Saut Edo Riko Manurung Yudi Pranoto