Numerical analysis of mixing in block‐head mixing screws

The research reported here used 3D non‐Newtonian flow simulations to investigate the pumping and mixing capability of block‐head mixers. Block‐head mixers are distributive mixing screws that are widely used to homogenize the polymer melt and eliminate thermal gradients. The polymer‐processing industry employs a variety of block‐head mixers, with little consensus on design and distribution of screw flights and mixing blocks. This analysis addresses this issue based on a computational design study in which the influence of three geometrical parameters was examined: (1) the number of flights at a mixing block, (2) the number of blocks along the screw, and (3) the stagger angle between the blocks. To examine the flow behavior of the mixing screws, the pressure consumption and energy dissipation is evaluated. Distributive mixing is analyzed using residence time distribution functions, kinematic stretching parameters, and the scale of segregation. Dispersive mixing is assessed by means of the mixing index and the shear stress. The results of this design study increase the understanding of block‐head mixers and contribute to the design and optimization of such geometries. The findings can further be applied to mixing screws of similar geometry, including pin‐type and knob mixers. POLYM. ENG. SCI., 59:E88–E104, 2019. © 2018 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.     

Taste of Water-Soluble Extracts Obtained from Over-Fermented Tempe

Over-fermented tempe, known as tempe semangit, is popular in Indonesian culture, especially in Java, as an umami seasoning in traditional foods. The objective of this study was to characterize taste-active compounds in water soluble extracts of over-fermented tempe. Over-fermented tempe was prepared from fresh tempe in which the fermentation was prolonged (0 to 96 h). Free amino acids in the water soluble extract were analyzed and characterized for their taste activity values. Water soluble extracts contained umami and bitter tasting free amino acids at relatively high concentrations. Their umami and bitter taste activity values were higher than the taste threshold concentration. Water soluble extract from 72 h over-fermentation had a higher umami taste activity value than bitter taste activity, exhibiting the highest umami taste dilution factor. The high-performance liquid chromatography profile of water soluble extract fractions obtained using Sephadex G-25 gel filtration chromatography demonstrated that fractions having higher umami taste intensity had more hydrophilic components than hydrophobic components.     

A review of the bioactivity and flavor properties of the exotic spice “andaliman” (Zanthoxylum acanthopodium DC.)

Andaliman (Zanthoxylum acanthopodium DC.) is a plant endemic to North Sumatera, Indonesia. It has been used as food ingredient because of its unique properties of its pericarp, such as its citrus-like aroma, warm peppery flavor, and its ability to induce a tingling sensation. However, the pericarp is easily degraded by environmental and processing conditions. Therefore, preservation techniques, such as encapsulation and drying, have been proposed to protect the flavor. Moreover, andaliman also has some potential biological activities related to its antimicrobial, antioxidant, and anti-inflammatory properties. Thus, this plant may have many health benefits and uses. This review discusses the flavor profiles and bioactive compounds of andaliman, in addition to its applications in the food industry as a flavoring ingredient.     

Nonlinear model predictive control for the polymorphic transformation of L‐glutamic acid crystals

Polymorphism, a phenomenon where a substance can have more than one crystal forms, has recently become a major interest to the food, speciality chemical, and pharmaceutical industries. The different physical properties for polymorphs such as solubility, morphology, and dissolution rate may jeopardize operability or product quality, resulting in significant effort in controlling crystallization processes to ensure consistent production of the desired polymorph. Here, a nonlinear model predictive control (NMPC) strategy is developed for the polymorphic transformation of L ‐glutamic acid from the metastable α‐form to the stable β‐form crystals. The robustness of the proposed NMPC strategy to parameter perturbations is compared with temperature control (T‐control), concentration control (C‐control), and quadratic matrix control with successive linearization (SL‐QDMC). Simulation studies show that T‐control is the least robust, whereas C‐control performs very robustly but long batch times may be required. SL‐QDMC performs rather poorly even when there is no plant‐model mismatch due to the high process nonlinearity, rendering successive linearization inaccurate. The NMPC strategy shows good overall robustness for two different control objectives, which were both within 7% of their optimal values, while satisfying all constraints on manipulated and state variables within the specified batch time. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Estimating city-level poverty rate based on e-commerce data with machine learning

Electronic Commerce Research - There are many big data sources in Indonesia, for example, data from social media, financial transactions, transportation, call detail records, and e-commerce. These...