Evaluation of Collapsibility of Compacted Loess Based on Resistivity Index

Recently, a lot of engineering constructions have been carried out in the Loess Plateau of China. However, the collapsibility of compacted loess as a filler poses a potential threat to the safety and stability of buildings. To address this threat, the scientific evaluation of the collapsibility of compacted loess has become a key to engineering construction. This study, therefore, tested the resistivity of compacted loess under varying conditions of water content, dry density, and its collapsibility coefficient under a pressure of 200 kPa. The correlation between collapsibility and electrical parameters was determined, and based on the resistivity, a new method to evaluate the collapsibility of the compacted loess is proposed. The results show that the resistivity of compacted loess decreases with an increase in water content and dry density and that the effect of water content is more significant. There is a critical water content value that causes the resistivity decay rate to slow down. The collapsibility coefficient also decreases with an increase in water content and dry density, and under the same dry density or same water content, the collapsibility coefficient and resistivity are positively correlated. According to the normalized resistivity value ρ / ρ w , the relative collapsibility coefficient δ s /0.015, and the water content ω obtained in the experiment, a collapsibility coefficient prediction model based on the resistivity of compacted loess was established. Using resistivity to evaluate the collapsibility of loess is nondestructive and provides a new method to accurately and quickly evaluate the collapsibility of compacted loess.

PENDUGAAN UMUR SIMPAN MAKANAN TRADISIONAL BERBAHAN DASAR BERAS DENGAN METODE ACCELERATED SHELF-LIFE TESTING (ASLT) MELALUI PENDEKATAN ARRHENIUS DAN KADAR AIR KRITIS

The expired date is important information that consumers should know. However, many traditional foods have not written an expiration due date. The purpose of this study was to estimate the shelf life of two (2) types of traditional rice-based foods intip and kembang goyang. Estimation of shelf life was carried out using the Accelerated Shelf-life Testing (ASLT) method using the Arrhenius approach and the critical moisture content approach. The calculation of shelf life in the Arrhenius approach to kembang goyang has been obtained respectively 0.45 months, 0.50 months, and 0.47 months at respective temperatures (25oC, 35oC and 45oC). The results of shelf life kembang goyang through the water content approach obtained 0.43 months at 75% RH. The results of the arrhenius approach to intip showed that shelf life of 0.37 months, 0.45 months, and 0.53 months at each temperature (25oC, 35oC, and 45oC). The critical water content approach for intip has obtained a shelf life of 0.58 months (RH 75%). Intip has a slightly larger shelf life when analyzed using the critical moisture content method. Keywords: ASLT, intip, kembang goyang, shelf life

Investigation into Freezing Point Depression in Soil Caused by NaCl Solution

Engineering practices illustrate that the water phase change in soil causes severe damage to roads, canals, airport runways and other buildings. The freezing point is an important indicator to judge whether the soil is frozen or not. Up to now, the influence of salt on the freezing point is still not well described. To resolve this problem, a series of freezing point tests for saline soil were conducted in the laboratory. Based on the relationship between the freezing point and the water activity, a thermodynamic model considering the excess Gibbs energy was proposed for predicting the freezing point of saline soil by inducing the UNIQUAC (universal quasi-chemical) model. The experimental results show that the initial water content has little influence on the freezing point if the initial water content is higher than the critical water content, while the freezing point decreases with the decrease of the water content if the initial water content is lower than the critical water content. Moreover, it is found that the freezing point is related to the energy status of liquid water in saline soils and it decreases with the increase of the salt concentration. Moreover, the freezing point depression of saline soil is mainly caused by the decrease of water activity. Compared with the other two terms, the residual term, accounting for the molecular interactions, has an obvious influence on the water activity. This result is helpful for understanding how salt concentration affects the freezing point of saline soil and provides a reference for engineering construction in saline soil areas.

Micellization of Polystyrene-b-Polyglycidol in Dioxane and Water/Dioxane Solutions

In this work, the self-assembly of a series of amphiphilic polystyrene-b-polyglycidol (PS-b-PGL) diblock copolymers in dioxane and dioxane/water mixtures is presented. The PS-b-PGL have an average degree of polymerization (DP) of PS block equal to 29 units and varied degrees of polymerization for the glycidol segments with DPs of 13, 42, 69 and 117. In dioxane, amphiphilic diblock copolymers form micelles with the hydrophilic PGL placed in the core. Critical micelle concentration (CMC) was determined based on the intensity of scattered light vs. concentration. The micelle size was measured by dynamic light scattering and transmission electron microscopy. Also, the behaviour of the copolymer was studied in water/dioxane solutions by following the changes of scattered light intensity with the addition of water to the system. Critical water content (CWC) of the studied systems decreased as the initial PS-b-PGL concentration in dioxane increased. This process was accompanied by a decrease in the size of aggregate formed. For a given initial copolymer concentration, the size of copolymer aggregates decreased linearly with increasing the length of the PGL block

Acceptability And Shelf Life Of Biscuit With Substitution Of Tuna Fish

Nutritional problems in Indonesia is still a serious health problem, especially of malnutrition and stunting. One of the efforts to improve the pattern of food consumption that aimed to overcome the malnutrition among the community, especially proteins, vitamins and minerals is by utilizing the tuna fish innards into fish meal innards in the form of biscuit. This study aims to know the acceptability and the shelf life of the biscuits with substitution of tuna fish innards. The method of research was pre experimental study with one shot group design. Acceptability was assessed by hedonic test among 35 panelists. Furthermore, the best formula was tested for critical moisture content to know it shelf life and the result was presented in tabular and narrative form. The results showed that the best panelist acceptance of biscuits with substitution of tuna starch ingredients was formula X02 (5% of tuna fish innards). In addition, there were about 54%, 66%, 77%, and 71% of panelist like the taste, scent, color and texture of the selected formula, respectively. The result of critical water content showed the biscuit has 48 days or 1,6 months of shelf life. For further study, it is suggested to make biscuits with 5% formula of tuna fish innards. Finally, various shelf life measurement might be consider.

Pengaruh Suhu Operasi terhadap Penentuan Karakteristik Pengeringan Busa Sari Buah Tomat Menggunakan Tray Dryer

A B S T R A C TFood damage can be caused by intrinsic and extrinsic factors. The causes of intrinsic factors involve water activity (aw) and moisture content, the level of maturity and the nature of the food material itself. Meanwhile, the causes of extrinsic factors were the air composition, temperature, pressure, population and microbial contamination. Drying is one of the most widely used preservative methods, namely by evaporating most of the water contained in food by heat energy. This work studied the effect of operating conditions on the characteristics of tomato drying using tray dryer with the addition of foaming agent albumin and carrier agent dextrin which function as foam stabilizer. Tomatoes used as raw materials were ripe tomatoes, fresh red, and the same relative diameter, not physiologically and mechanically damaged. In this work, tomatoes were sliced, crushed for 10 minutes using blender, separated from the seeds and the residues with a 60-mesh sieve, and then mixed with dextrin and foaming agent albumin each as much as 5% weight. The mixture was blended for 10 minutes. The tray dryer was filled with hot air at 2.0 m/sec with temperature variation of 40, 50, 60 or 70°C. The stainless-steel dish containing tomato paste with thickness of 2 mm or 4 mm was inserted to the dryer. The tomato paste was weighted every 5 minutes. It is found, at a thickness of 2 mm, the optimum drying occurred at a temperature of 70 ℃ with critical time, tc, for 0.92 hours, critical water content of the sample, Xc, 1.40 %, and constant drying rate, Rc, 897.12 kg/m2.hour. In drying operations of 4 mm thickness, optimum drying occurs at 50 ℃ temperature with critical time, tc, for 1.92 hours, critical water content of sample, Xc, 2.56 %, and constant drying rate, Rc, 175.52 kg/m2.hour.Keywords: cake thickness, drying rate, foaming agent, tomato, tray dryer.A B S T R A KTerjadinya kerusakan bahan pangan dapat disebabkan oleh faktor intrinsik dan ekstrinsik. Penyebab faktor intrinsik di antaranya aktivitas air (aw) dan kadar air, tingkat kematangan dan sifat bahan pangan itu sendiri. Sedangkan penyebab dari faktor ekstrinsik seperti komposisi udara, suhu, tekanan, populasi dan tingkat kontaminasi mikrobia. Pengeringan merupakan salah satu metode pengawetan yang paling banyak digunakan, yaitu dengan cara menguapkan sebagian besar air yang terkandung di dalam bahan pangan dengan menggunakan energi panas. Penelitian ini mempelajari karakteristik pengeringan busa sari buah tomat menggunakan tray dryer dengan penambahan foaming agent albumin dan carrier agent dextrin yang berfungsi sebagai foam stabilizer. Tomat yang digunakan sebagai bahan baku adalah tomat matang, merah segar, diameter relatif sama, tidak rusak secara fisiologis dan mekanis. Di dalam penelitian ini, tomat diiris dan dihaluskan menggunakan blender selama 10 menit. Biji dan ampasnya dipisahkan dari bubur tomat dengan ayakan berukuran 60 mesh. Kemudian bubur tomat dicampurkan dextrin dan foaming agent albumin masing-masing sebanyak 5% berat. Campuran tersebut dihaluskan dengan blender selama 10 menit. Tray dryer dialiri udara panas dengan laju 2,0 m/detik dengan variasi temperatur 40, 50, 60 atau 70 oC. Loyang stainless steel yang berisi bubur tomat dengan ketebalan 2 mm atau 4 mm dimasukkan ke dalam tray dryer. Berat bubur tomat diukur setiap 5 menit. Hasil yang diperoleh, pada ketebalan 2 mm, pengeringan optimum terjadi pada temperatur 70 ℃ dengan waktu kritis, tc, selama 0,92 jam, kadar air kritis sampel, Xc, 1,40 %, dan laju pengeringan konstan, Rc, 897,12 kg/m2.jam. Pada operasi pengeringan dengan ketebalan 4 mm, pengeringan optimum terjadi pada temperatur 50 ℃ dengan waktu kritis, tc, selama 1,92 jam, kadar air kritis sampel, Xc, 2,56 %, dan laju pengeringan konstan, Rc, 175,52 kg/m2.jam.Kata kunci: foaming agent, ketebalan bubur, laju pengeringan, tomat, tray dryer.

Pembuatan dan Pendugaan Lama Simpan Bubuk Asam Sunti dalam Kemasan dengan Metode Sorpsi

Asam sunti is a typical seasoning Aceh cuisine made by processed belimbing wiluh (Averhoa bilimbi. L) in the form of semi-wet. Making asam sunti in powder form as well as other spices such as pepper, turmeric, and ginger others is expected to simplify and expand the asam sunti market as spice. The aim of this research were to make asam sunti powder, to analyze the effect of packing type on the change of water content of asam sunti powder, and to the estimation of shelf life of asam sunti powder in the packaging. Preparation of asam sunti powder was carried out by drieying a semi-wet asam sunti at temperature 70°C for 12 hours. Dried asam sunti was blended and sieved (80 mesh). Measurement of isotherm sorption properties was done using the salts of NaOH (6.9%), NaBr (56%), NaNO2 (64%), NaCl (75.3%), and KCl (83.6%) to regulate the humidity. The packaging tested for asam sunti powder storage was aluminum foil, HDPE and PP. Critical water content to a determine of shelf life of asam sunti powder at 21.26% with powder conditions starting to clot and not accepted by consumers. The estimation of shelf life of asam sunti powder with sorption method for aluminum foil, PP and HDPE packaging were 541.81, 506.83 and 369.24 days at 75% RH storage respectively, while RH of 83% was 364.12, 337.50 and 245.88 days. These results indicate that the best packaging for asam sunti powder was aluminum foil.AbstrakAsam sunti merupakan bumbu khas masakan aceh yang terbuat dari olahan belimbing wuluh dalam bentuk semi basah. Membuat asam sunti dalam bentuk bubuk seperti halnya bumbu lain yaitu lada, kunyit, jahe bubuk, dan yang lainnya diharapkan memudahkan dan memperluas pasar asam sunti sebagai bumbu masakan. Penelitian ini bertujuan menganalisa pengaruh jenis kemasan terhadap perubahan kadar air asam sunti bubuk dan pendugaan umur simpan asam sunti bubuk dalam kemasan. Pembuatan asam sunti bubuk dilakukan dengan pengeringan suhu 70oC selama 12 jam. Asam sunti kering diblender dan diayak (80 mesh). Pengukuran sifat sorpsi isotermis dilakukan menggunakan garam NaOH (6.9%), NaBr (56%), NaNO2 (64%), NaCl (75.3%), dan KCl (83.6%) untuk mengatur kelembaban. Kemasan yang diuji untuk penyimpanan adalah aluminium foil, HDPE dan PP. Kadar air kritis sebagai penentu umur simpan pada nilai 21.26% dengan kondisi bubuk mulai menggumpal dan tidak disukai konsumen. Pendugaan umur simpan asam sunti bubuk dengan metode sorpsi untuk kemasan aluminium foil, HDPE dan PP berturutturut adalah 541.81, 506.83 dan 369.24 hari pada penyimpanan RH 75%, sedang pada penyimpanan RH 83% berturut-turut 364.12, 337.50 dan 245.88 hari. Hasil ini menunjukkan bahwa kemasan yang terbaik untuk menyimpan asam sunti bubuk adalah jenis aluminium foil.

Physical quality of a Luvisol under agroforestry systems in a semi-arid region, Brazil

Agroforestry systems provide many environmental benefits in semi-arid regions; however, trampling by cattle, and agricultural practices, can degrade physical quality of the soil. The aim of this study was to evaluate the degree of compaction and the compression behaviour of a Luvisol after 14 years under agro-silvopastoral (ASP) and silvopastoral systems (SILV), compared with a soil under natural vegetation (NV). We evaluated the degree of soil compactness, compaction index, pre-consolidation pressure, maximum bulk density, critical water content and the stocks of total organic carbon (C), organic matter (OM), C in light organic matter (LOM), and nitrogen (N) in LOM. The results indicated that agroforestry systems change the compressive behaviour of the soil, increasing maximum bulk density (P < 0.05) and reducing critical water content (P < 0.05). Despite the increases in maximum bulk density, changes induced by agroforestry system did not affect the pore space, as shown by similar values for degree of compactness (P > 0.05) under ASP, SILV and NV. This suggests a change in the quality of OM, as evidenced by the lower values for stocks of N in LOM (P < 0.10) and total organic C (P < 0.05) under ASP and SILV, whereas pre-consolidation pressure was unaffected (P > 0.05). After 14 years, the degree of compactness and load-bearing capacity of the soils under ASP and SILV had not increased, being suitable for plant growth.