Low-temperature Grinding Research Articles

Mechanofluorochromic properties of 1-phenylanthracene derivatives with extremely simple structures

Several types of 1-phenylanthracene derivatives 1–4 were prepared and their photophysical properties were observed in the solution and solid states. Interestingly, the fluorine-substituted 1-phenylanthracene derivative 1c was found to exhibit a higher fluorescence quantum yield (Φf=0.57) in the solid state than in the solution state, probably due to the formation of intermolecular Ar–F•••H–Ar hydrogen bonds. Additionally, some of the 1-phenylanthracene derivatives exhibited mechanofluorochromic properties depending on the substituents of the phenyl group, with the derivatives having CF3, OMe, and CN substituents (1d-1f, 2, 3) showing a significant change in luminous color from a bluish to greenish color at “room temperature” after grinding. However, no change in the luminous color was observed for the derivatives having H, Me, and F substituents (1a-1c) at “room temperature” but luminous color change was observed with low temperature grinding (−78 °C), especially for the CN substituent, in which a significant change in the luminous color was observed at “room temperature” probably due to the formation of Ar-CN•••H–Ar hydorogen bond interactions. Interestingly, for the 1-phenylanthracene derivative 3 substituted with two CN groups, which exhibited a solvatochromic phenomenon, the luminous color recovered with controllable rate from green to bluish when heated and fumed with solvent vapor in the solid state, and the luminous color change with controllable recovery rate was repeatedly successfully observed. These anthracene derivatives have extremely simple structures and could probably be applied as new mechanofluorochromic materials.

A low temperature nano-lubrication method for enhancing machinability in ultra-precision grinding of binderless tungsten carbide (WC)

This paper presents a low temperature nano-lubrication method, using a vortex tube to generate a low temperature grinding environment for increasing heat transfer with a mixture of nanoparticles as a nano-lubricant for reducing friction in ultra-precision grinding of tungsten carbide. The results show the method significantly reduces wheel deterioration and improves workpiece surface integrity. The arithmetical mean height (Sa) and maximum height (Sz) were reduced by 50.8% and 65.3% respectively, with wheel deterioration 57.8% lower than traditional minimum quantity lubrication. These results were obtained by optimized low temperature gas at −20 °C and MoS2/Fe3O4 nano-lubricant with mix-ratio 1:2.

Effect of low temperature grinding on phytochemicals profile of fenugreek seed powder

The grinding of spices at ambient temperature causes the loss of valuable heat-sensitive constituents. While higher investment and maintenance of cryogenic grinding make it prohibitive for small-scale industries. So, the present study was carried out to check the effects of low-temperature grinding on various phytochemicals of ground powder of fenugreek seeds. Water at ambient temperature, chilled water and coolant were circulated around the grinding chamber to lower the grinding temperature. Additionally, fenugreek seeds were fed at ambient and low temperatures (-100C). The temperature inside the grinding chamber at the end of grinding for three kg of fenugreek seeds ranged from 91.330C–53.330C for different treatments. A fall in grinding temperature resulted in the retention of a higher quantity of total phenol (7.71 mg g-1), total flavonoid (12.08 mg quercetin equivalent/g extract), antioxidant activity (21.29%) and volatile components in powder of fenugreek seeds ground by coolant circulation with low-temperature feed.

A promising strategy for mechanically modified wheat flour by milling of wheat endosperm

A planetary mill was used to grind pure endosperm granule flour using both low-temperature control and normal modes. Particle size distribution, microstructure, pasting characteristics, water absorption indexes, solubility indexes, in vitro digestibility, and thermal characteristics were determined for samples ground for different lengths of time. The resulting flour had D50 below 30 μm and crushed starch content of 8%. Better dispersion of protein and starch was achieved for low temperature grinding and increased grinding time. Independently of temperature, milling decreased peak viscosity, trough viscosity (from 2339 to 1896 cp), and final viscosity (from 3947 to 3535 cp). The water solubility also decreased. There was also a decrease in the enthalpy (ΔH) of gelatinization, and the enthalpy (ΔH) of gelatinization at low temperature was higher at normal temperature. The rapidly digestible starch content was lower and slowly digestible starch content was higher in flour compared with raw material, and the changes in the low and normal modes showed opposite trends, probably influenced by the starch granules surface-protein and starch amorphous regions. The above results suggest that the functional properties of wheat flour were significantly altered by planetary ball milling at low speed and short duration (<200 rpm, <30 min), suggesting potential strategies to expand the flour food applications.

Fluid Convection Models for Low-Temperature Grinding and Effect of Fluid Warming

AbstractThe paper considers fluid convection in low-temperature grinding. Fluid cooling often predominates over all other forms of heat dispersion in the grinding zone particularly in low-temperature grinding. Experimental values of convection heat transfer coefficient (CHTC) up to and in excess of 200,000 W/m2K have been found by various researchers both for water-based emulsions and in one case for mineral oils employed in high wheel-speed grinding. Several convection models have been developed in recent years for the prediction of CHTCs in low-temperature grinding. This paper reviews advances in convection modeling and reconsiders the basic assumptions implied. A proposal is made for improved estimation for highly churned flow assuming a degree of fluid warming. Predicted coefficients are compared with measured values.

The Design and Performance of Continuous Porang (Amorphophallus muelleri Blume) Flour Mills

Indonesian Porang flour (Amorphophallus muelleri Blume) is made into glucomannan flour because of its beneficial health effects. However, the challenge in producing flour is calcium oxalate which must be eliminated, because it can irritate the skin and may cause a kidney stones if the flour is consumed. Over the past 10 years, several batch grinding methods have been used to produce good quality Porang flour. However, there has been no research on the continuous method of grinding Porang flour using a ball mill. Both the stamp mill and batch type ball mill processes had low production capacities. Therefore, the aim of this work is to design a Continuous Porang Flour Mill (CPFM) machine and test its performance for Porang flour production. The CPFM machine consists of a continuous ball mill and a cyclone separator. The experiments were carried out at a ball mill rotation speed of 65 ± 1 rpm, with a capacity of up to 780.67 g / h input of chip material, producing an output of 33.1 - 57.1%. The CPFM meets the low-temperature grinding requirements but is still needed to provide acoustic hearing protection for the operator due to the high level of loudness. CPFM produces Porang flour with glucomannan levels ranging from 80.79% to 87.79% and calcium oxalate ranging from 0.12% to 0.29%. The calcium oxalate content overall was under 0.3%, which is better compared when compared to other milling methods.

Study of Convective Heat Transfer in Grinding Applied to Tool Carbide

Abstract The grinding temperature is of great importance for the quality and integrity of machined cemented carbide tool. Tool edge surfaces may be damaged by softening or being stressed, hardened, burned, or cracked. Former research on grinding temperature prediction often made assumptions to simplify heat convection due to the grinding fluid. However, these simplifying assumptions can sometimes undermine the mathematical relationships between grinding conditions and surface temperature, particularly in low-temperature grinding where fluid convection is most important. This paper is an attempt to provide an improved comprehensive thermal model for the prediction of contact temperatures and for monitoring and control of thermal damage. Based on previous thermal model research, this paper tackles a key element of the thermal model for temperature prediction. It proposes a convective heat transfer model based on the classic theory of turbulent flow passing a plate. Theoretical predictions from the thermal model of turbulent flow developed in this paper are compared with experimental values. Predictions are further compared with values from a previously published laminar flow model. And it is shown that the new model leads to a significant reduction in predicted temperatures. The results suggest that the thermal model for the turbulent flow provides a reasonable estimate of predicted temperature values within the region of the fluid boiling temperature. The estimates appear to be an improvement compared with the laminar flow thermal model. The turbulent flow thermal model is considered to improve estimates of background contact temperatures in grinding cemented carbide.

Performance evaluation of developed low‐temperature grinding mill

AbstractThe performance evaluation of the developed low‐temperature grinding mill was carried out on the basis of temperature inside the grinding chamber at the end of grinding, flour temperature, and time of grinding; while aiming to minimize the milling loss. Turmeric powder ground at low temperature was analyzed on the basis of volatile oil, protein, carbohydrates, moisture, fat, and ash content and compared with that of turmeric ground at ambient temperature (control treatment). It was found that low‐temperature ground turmeric contains more volatile oil, protein, carbohydrates, and fat. Volatile oil analysis of the control treatment and the best between all treatments were carried out using GC–MS. Major compounds, namely ar‐curcumene, ar‐tumerone, γ‐curcumene, and monoterpenes, present in volatile oil were retained in low temperature ground turmeric sample that were not found in the sample of control treatment.Practical ApplicationsThis low‐temperature grinding mill operates efficiently with less cost as compared to other existing low temperature grinding technologies while maintaining the nutritional quality, aroma, and flavor of the product.

Studying the complex of biologically active substances in spicy vegetables and designing the nanotechnologies for cryosupplements and nanoproducts with health benefits

We determined the complex of BAS of spicy vegetables (roots of ginger, celery, horseradish, and garlic), which differ from other vegetable raw materials by a high content of unsaturated reactive phyto-substances. It includes volatile aromatic substances, low-molecular and high molecular phenolic compounds. The latter are natural antioxidants, preservatives and have a bactericidal and an immunomodulating effect. We found that spicy vegetables have a high content of prebiotic substances (cellulose, pectin, and protein); they are low in sugar. The presence of the specified BAS in 100 g of spicy vegetables in the amounts that can satisfy a daily need of the human body, as argued by authors, provides fresh vegetables with direct therapeutic and prophylactic properties.We developed the nanotechnologies for healthy frozen supplements and nanoproducts produced from spicy vegetables, which fully preserve vitamins, aromatic substances, phenolic compounds and other BAS of fresh raw materials. In addition, we found the hidden (bound) forms of BAS in the course of development of nanotechnologies and extracted them into a freely assimilable state. The mass fraction of these substances is 2.5...3.2 times higher than that in fresh vegetables, which we can control by standard chemical methods. We propose to use the cryogenic treatment of raw materials, which includes a cryogenic shock freezing and a finely dispersed low temperature grinding (mechanolysis), as the innovation in the development of technologies.The advantages imply that it became possible to obtain frozen spicy vegetables, which, in terms of the content of natural aromatic substances and phytocomponents (phenolic compounds, polyphenols and other BAS), exceed fresh spicy vegetables by 2...2.5 times. We worked out the technological modes at the semi-industrial bench equipment. We developed technologies for health-improving supplements in the form of finely dispersed purees and frozen spicy vegetables.That makes it possible to develop a wide range of health products that outperform known analogues in quality using the obtained frozen products and supplements of spicy vegetables.

ELABORATION OF NEW METHOD OF DEEP PROCESSING OF CARO-TENE-CONTAINING RAW MATERIALS INTO NANOADDITIVES WITH THE USE OF CRYOGENIC FREEZING AND FINE-DISPERSED GRINDING

The aim of the work is elaboration of principally new cryogenic method of deep processing of carotene-containing vegetable raw material (CCVRM) such as carrot, pumpkin, sweet Bulgarian pepper, tomato, sea buckthorn, apricot using cryogenic freezing and fine-dispersed grinding. The new method of deep processing leads to more full extracting and removal of β-carotene from the state, bound with biopolymers into free and hydrophilic form. The mechanism of these processes was presented. It was established, that mass share of β-carotene in cryopuree, received by the new method, exceeds its content in initial (fresh) CCVRM in 3,0…3,5 times. The regularities of growth and transformation of carotenoids separately at freezing with different high speeds and low-temperature grinding of CCYRM were established. It was demonstrated, that at cryogenic freezing take place quantitative increase of mass share of carotenoids in 2,0…2,5 times comparing with initial (fresh) raw material depending on freezing speed and type of CCVRM. That is it was demonstrated, that frozen carotene-containing vegetable raw material contains 2,0…2,5 times more β-carotene than fresh one. Mechanism of these processes was presented. It was demonstrated, that cryopuree of CCVRM, received using new methods of deep processing, exceeds the initial (fresh) raw material by the content not only β-carotene but also other low-molecular bioactive substances: L-ascorbic acid – in 2,0…2,2 times, phenol compounds – in 1,7…1,8 times, tanning substances – in 1,5…1,7 times). That is they have principally new chemical composition, because practically all bioactive substances (BAS) in cryopuree are in nanosize form and easily assimilated by human organism.

Development of nanotechnology of fine frozen champignon puree (agaricus bisporus)

The nanotechnology of fine-dispersed frozen champignon puree with unique characteristics using the mechanical destruction and mechanical activation processes was scientifically substantiated and developed. The new technology allows to extract the forms of BAS and biopolymers (proteins) hidden in vegetable raw materials and make fuller use of the biological potential of raw materials. Quality comparison of frozen fine additives, obtained by the innovative technology in the form of nanostructured puree with the feedstock by the content of BAS was performed in the paper. It is shown that in the freezing and low-temperature grinding of raw materials, accompanied by cryodestruction and mechanical activation processes, there is a fuller extraction of BAS from the biopolymers-bound state into the free state. Depending on the type of BAS, the increase is from 1.5...2.5 times with respect to the fresh feedstock. Comprehensive investigations have shown that the resulting fine frozen puree has fundamentally new properties. It was found that in the fine low-temperature grinding of champignons, there is a destruction of protein-chitin-mineral complexes, mechanical disruption (mechanolysis) of proteins. It was revealed that using mechanical activation in cryogenic mechanical grinding of champignons into fine puree leads to cryodestruction and mechanolysis of proteins of mushrooms to free amino acids by 70...75 %, that is, the protein is transformed (modified) into the nanostructured form, 2/3 of which consist of free amino acids and is much better dissolved and absorbed by a human body. The end result of the work is the developed and approved regulatory documentation for the product, as well as conducted testing in the industrial environment at the enterprises of the city of Kharkiv.

Feasibility study of evaporative water cooled (EWC) grinding method for chilli (Capsicum annum L.)

The application of low temperature grinding shows promising pathway to produce higher quality ground product in terms of flavour and volatile oil retention of spices. The possibility of using evaporative water cooling for grinding chilli was studied to ascertain the quality parameters. Atomized water was sprayed on to the chilli pods being fed in to the mill. The temperature, moisture content and colour values of the ground product were measured and the values were compared with conventional grinding. The temperature of the conventionally ground and evaporative water cooled ground chilli were 58 ± 2.65 °C and 36 ± 1.5 °C respectively and the corresponding amounts of heat removed by water vapour were 29.33 kJ and 186.50 kJ. The moisture content of conventionally ground chilli and evaporative water cooled ground chilli with water spraying were 9.06 ± 0.41 and 9.65 ± 0.23 percent wet basis and the corresponding colour values were 49.19 ± 0.99 (L*), 17.35 ± 1.62 (a*), 23.38 ± 1.29 (b*) and 47.52 ± 1.74 (L*), 18.38 ± 0.14 (a*) and 26.93 ± 0.68 (b*). This study revealed that the water can be effectively used as a coolant for reducing temperature rise during grinding in order to preserve the quality of chilli. Tropical Agricultural Research Vol. 26 (1): 189 – 194 (2014)

Design of Green Processing Chain for Processing of Ginseng Fruit Vinegar

Using ginseng, wild wine and acetic acid to the orthogonal experiment method to determine the fermentation process, low temperature and cryogenic grinding fermentation brewing vinegar. The results showed that: cryogenic grinding with a significant impact on the quality of the wine, the best ginseng vinegar fermentation parameters for initial dosage of 6% alcohol, fermentation temperature was 31 °C, fermentation time was 96h.By mixed fermentation Changbai Mountain forest berries and ginseng significantly alter the flavor of vinegar.

Innovative technologies of vitamin fruitberry iсе-cream production using frozen fine-dispersed additives made of plant raw materials

The objective of the paper is the scientific substantiation of technologies for producing new kinds of fruit-berry ice-cream and fine-dispersed additives using a cryogenic “shock” freezing and low-temperature grinding for producing healthy products with high content of BaS. In the paper the quality of frozen fine-dispersed additives made by the innovative technology in the form of nanostructured puree was compared with feedstock in regard to BaS content. It is shown, that under conditions of feedstock freezing and low-temperature grinding, accompanied by cryogenic destruction and mechanical activation processes, BaS is more fully extracted from a biopolymer-bound into a free state. The increase rate of BaS extraction depends on its kind and varies from 1.6 to 2.9 times with respect to fresh feedstock. Technology, technological scheme and three formulations of new fruit-berry ice-cream (“Vitaminchik”, “limonchik”, “Tropik”) were developed, with their quality analysis in respect to BaS content. It is shown that new healthy fruit-berry ice-cream is better than the native analogues by its chemical composition and competes with the best foreign analogues, as it contains a great amount of BaS: vitamin C, phenol compounds, tanning substances, organic acids, pectin and mineral substances. Thus, 100 g of the fruit-berry ice-cream “Vitaminchik” contains the daily norm of vitamin C, “limonchik” and “Tropik” have half of the daily norm of this vitamin. Moreover, new kinds of ice-cream have a significant content of phenol compounds, tanning, pectin and mineral substances, etc. The quality of Ir spectrums of new kinds of ice-cream was compared to their analogue (“Snihovyk” fruit-berry ice-cream, “Khladoprom” PrJSC). The final result of the work is the development of the Scientific research Project on nanostructured puree and new kinds of fruit-berry ice-cream. Furthermore, new kinds of ice-cream have passed degustation and approbation in production environment at Kharkov enterprises (“Khladoprom” PrJSC, “Polus LTD” SUIS LLC).

The Experimental Study on Characteristics of Low-Temperature Grinding of Ceramic Hollow Ball Super-Hard Composite Abrasive

Ceramic hollow ball Super hard composite abrasive has spherical hollow Mini-bore structure, This article introduced the structure of hollow spherical super hard abrasive, grinding model and the experimental investigations were conducted, It is found that the grinding wheel with hollow ball Super hard composite abrasive has more holes in the working layer of grinding wheel and can carrying more cooling fluid into the grinding area for heat exchanges, thus reducing the grinding temperature.

A Study on the Retention of Fresh Flavour of Cardamom Oil by Cold Grinding

Grinding is a very important step in processing of Cardamom as it involved the additional problem of volatility and loss of aroma giving essential oil present in it, which is the sole criterion of quality of this spice. The aroma compounds present in whole dried Cardamom were hydrodistilled by ordinary grinding method and after cold grinding with ice in order to collect the essential oil. Low temperature grinding is the practical way to achieve fine grinding without loss of flavour principles. The process of cold grinding enhances the volatile oil content and the quality of the oil in terms of its aroma constituents. A Comparative study of the control sample (ambient condition, 30°C, ground) with that of improved grinding technique was performed quantitatively and qualitatively by GC-MS Analysis. By this method of cold grinding (2–5°C) and Extraction of volatile oil, the qualitity profile of the oil is found to be enhanced in terms of its number of constituents as well as its percentage. The results also showed that the oil content has increased by 1% and the study of the Chemical components established that the major components are oxygenated terpenoids, which contribute the fresh aroma. The percentage of essential oil and the Chemical composition of the cold ground sample exihibited the superiority of the product. Thus this technique may be used in the flavor industry for improving the quality of the product quantitatively as well as qualitatively.

Study of the processes of mechanical-thermal treatment of food dispersed materials

The paper presents experimental data for the processes of low-temperature vacuum drying and grinding of thermolabile materials in devices with spring members.

Effect of Guest Species on Inclusion Compound Formation of Deoxycholic Acid by Co-Grinding

Abstract Deoxycholic acid (DCA) was ground with a guest compound by using a vibrational mill. Powder X-ray diffraction, differential scanning calorimetry, and fluorescence spectroscopic data indicated the formation of the inclusion complex in the ground mixture of DCA–phenanthrene and DCA–naphthalene systems. The DCA–naphthalene ground mixture was found to have higher crystallinity than the DCA–phenanthrene ground mixture, and this was assumed to relate to the difference in the crystallization temperature of the inclusion complex. When low-temperature grinding was performed for DCA and other aromatic hydrocarbons along with naphthalene and phenanthrene, all the ground mixtures were obtained in amorphous state. Crystallization of inclusion compounds from the amorphous ground mixtures was observed to occur at a higher temperature as the stoichiometric ratio (DCA/guest) of the compound increased. With regard to the formation of crystalline complex between DCA and a guest, such as naphthalene, by grinding at room temperature, a two-step mechanism was proposed: i.e., (i) amorphization of both DCA and guest crystals, and (ii) crystallization of the inclusion complex induced above a certain temperature.

Effect of Cryogrinding on Physico-Chemical Properties of Drugs. II. Cortisone Acetate: Particles Sizes and Polymorphic Transition

AbstractThe low temperature grinding (at 78 K) of cortisone acetate was carried out. From electron microscopy data, there were determined a form, mean linear sizes of particles and then specific surface was calculated. From X-ray data, a part of microcrystalline fraction in cryogrinded samples was calculated. As was indicated by X-ray data, the mechano-induced phase transition from “monoclinic” phase (form FI) to “orthorhombic” one (form FII) takes place as a result of I0-min grinding. The transition is confirmed by IR-spectroscopy results too. The local pressures induced by the mechanical stress seems to be the main cause of the phase transition observed.

Effect of Cryogrinding on Physico-Chemical Properties of Drugs. I. Theophylline: Evaluation of Particles Sizes and the Degree of Crystallinity, Relation to Dissolution Parameters

An activation of crystalline form of theophylline was carried out by low temperature grinding (at 78 K). From electron microscopy data, there were determined the form, mean linear sizes of particles and then specific surface was calculated. From X-ray data, a fraction of microcrystalline phase in cryogrinded samples was calculated and it was showed that the intense defect formation process takes place up to partial amorphization at final stage of mechanical treatment. By ultra-violet spectroscopy, the solution behaviour of initial (intact) and activated forms of theophylline was studied. The values of solution rate and solubility for activated forms are 12 and 1.5 times greater accordingly then ones for initial form. On the basis of experimentally determined thermodynamic characteristics of solution process for the initial and activated forms, the thermodynamic characteristics of theophylline activation were calculated.