Corn Milling Research Articles

Productive performance and blood parameters of bulls fed diets containing babassu mesocarp bran and whole or ground corn

The objective of the present study was to evaluate the effects of corn milling and the inclusion of babassu mesocarp bran (BMB) on productive performance, digestibility of dietary nutrients, and blood parameters of dairy crossbred (Holstein-Gyr) bulls finished in confinement. Twenty-four bulls were fed four different experimental diets, containing two levels of inclusion of BMB (0 and 41.24%) and corn supplied in two different forms (ground and whole), for 98 days (77 days of data collection and 21 days of adaptation). The intakes and digestibility coefficients of the dry matter (DM) and nutrients were determined. There were no significant interaction effects of the BMB inclusion level and the form of corn used on the performance and digestibility variables. The intakes of DM, crude protein (CP), and neutral detergent fibre (NDF) increased with the inclusion of BMB in the diets. However, the inclusion of BMB in the diets decreased the ether extract intake, the NDF apparent digestibility, and the feed efficiency of DM and CP. Dry matter and NDF intakes also increased with the use of ground corn in the diet, which promoted an increase in the intake of total digestible nutrients (TDN), digestibility of non-fibrous carbohydrates, and average daily gain. However, the supply of ground corn reduced the feed efficiency of TDN. The remaining measured variables did not vary with the tested diets. The levels of plasma protein and albumin remained normal, but glucose concentrations were always high, irrespective of the tested diet. The form of corn supplied and the level of BMB inclusion had a significant interaction effect on the levels of triglycerides, urea, aspartate aminotransferase, and alkaline phosphatase. Babassu mesocarp bran can be included up to 41.24% in the diet of confined bulls without a negative effect on the animal weight gain. Corn should be supplied ground because this form improves the performance of crossbred bulls

Determination of maize hardness by biospeckle and fuzzy granularity

In recent years there has been renewed interest in the development of novel grain classification methods that could complement traditional empirical tests. A speckle pattern occurs when a laser beam illuminates an optically rough surface that flickers when the object is active and is called biospeckle. In this work, we use laser biospeckle to classify maize (Zea mays L.) kernel hardness. A series of grains of three types of maize were cut and illuminated by a laser. A series of images were then registered, stored, and processed. These were compared with results obtained by floating test. The laser speckle technique was effective in discriminating the grains based on the presence of floury or vitreous endosperm and could be considered a feasible alternative to traditional floating methods. The results indicate that this methodology can distinguish floury and vitreous grains. Moreover, the assay showed higher discrimination capability than traditional tests. It could be potentially useful for maize classification and to increase the efficiency of processing dry milling corn.

Incidence and Predictors of Hand-Arm Musculoskeletal Complaints among Vibration-exposed African Cassava and Corn Millers.

BackgroundCassava and corn milling is a growing small-scale enterprise in Africa. We aimed to determine the incidence of hand–arm musculoskeletal complaints among vibration-exposed Congolese cassava and corn millers in the previous 12 months.MethodsA cross-sectional study was conducted, prior to a follow-up study, from March to May 2013 among cassava/corn millers in Lubumbashi, Democratic Republic of Congo, in which 365 millers age-matched to 365 civil workers anonymously answered a questionnaire.ResultsOverall incidence of hand–arm musculoskeletal complaints was 25.8% in millers (vs. 5.2% in civil workers; p < 0.001). The risk of experiencing musculoskeletal symptoms was seven times higher in millers [vs. civil workers; odds ratio (OR) = 7.10; 95% confidence interval (CI): 4.03–12.50; p < 0.0001]; 2.4 times higher in smoking millers (vs. smoking civil office workers; OR = 2.36; 95% CI: 1.42–3.88; p < 0.001); 3.6 times higher in millers with longer daily exposure (> 8 hours; vs. those working ≤ 8 hours; OR = 3.56; 95% CI: 1.93–3.61; p = 0.026); and 7.4 times higher in young millers (vs. older millers, OR = 7.39; 95% CI: 1.29–75.52; p < 0.001). Smoking, number of cigarettes, and daily exposure duration were positively correlated with musculoskeletal complaints.ConclusionThis study revealed a relatively high incidence of musculoskeletal complaints among African cassava and corn millers. The use of anti-vibration protective equipment and the regulation of this hazardous occupation may reduce the burden of musculoskeletal disorders in millers.

Energy Potential and Greenhouse Gas Emissions from Bioenergy Cropping Systems on Marginally Productive Cropland

Low-carbon biofuel sources are being developed and evaluated in the United States and Europe to partially offset petroleum transport fuels. Current and potential biofuel production systems were evaluated from a long-term continuous no-tillage corn (Zea mays L.) and switchgrass (Panicum virgatum L.) field trial under differing harvest strategies and nitrogen (N) fertilizer intensities to determine overall environmental sustainability. Corn and switchgrass grown for bioenergy resulted in near-term net greenhouse gas (GHG) reductions of −29 to −396 grams of CO2 equivalent emissions per megajoule of ethanol per year as a result of direct soil carbon sequestration and from the adoption of integrated biofuel conversion pathways. Management practices in switchgrass and corn resulted in large variation in petroleum offset potential. Switchgrass, using best management practices produced 3919±117 liters of ethanol per hectare and had 74±2.2 gigajoules of petroleum offsets per hectare which was similar to intensified corn systems (grain and 50% residue harvest under optimal N rates). Co-locating and integrating cellulosic biorefineries with existing dry mill corn grain ethanol facilities improved net energy yields (GJ ha−1) of corn grain ethanol by >70%. A multi-feedstock, landscape approach coupled with an integrated biorefinery would be a viable option to meet growing renewable transportation fuel demands while improving the energy efficiency of first generation biofuels.

Influência da granulometria da matéria-prima na expansão de extrusados de milho

Na produção de extrusados de milho, a indústria usualmente emprega o grits, que consiste no milho limpo, degerminado e moído em granulometria média. Entretanto, visando à redução dos custos de produção, fabricantes de snacks extrusados de milho vêm utilizando o fubá em substituição ao grits, devido ao menor custo apresentado por este. O objetivo deste trabalho foi verificar a influência da granulometria do milho sobre o índice de expansão dos snacks, sua textura e aceitação sensorial. Para isso, foram utilizadas três diferentes granulometrias do milho moído, sendo: grits, fubá mimoso e fubá mimoso fino. O índice de expansão radial foi analisado pela razão entre o diâmetro médio do snack e o diâmetro da matriz utilizada, a textura foi analisada em texturômetro, modelo Texture Analyser TA-XT Plus (Stable Micro Systens). A partir dos resultados obtidos, houve a confirmação da influência da granulometria nos parâmetros físicos, entretanto, não ocorreu alteração na aceitação do produto, indicando, desta forma, ser viável a substituição do grits pelo fubá na produção de snacks sob o ponto de vista do produto final.

찰옥수수쌀의 품종별 이화학특성 및 취반특성

ABSTRACT Consumption of waxy corn is steadily increasing due to consumer preference for natural food. However, availability of waxy corn is limited because most of them are used for steamed waxy corn. It is therefore important to create new demands of waxy corn using food processing technology. There is little prior research about characteristics of milled kernel in waxy corn. This study examined the physicochemical and cooking properties of milled kernel using nine waxy corn hybrids. Colored hybrids (Heukjinju, Miheukchal, and Eolrukchal1) showed high milling yield and low change of grain length after milling process compared to other hybrids. The total starch content ranged from 62.1 to 68.4% and the gelatinization temperature of starch was lowest in Yeonnong1 (69.9℃). The breakdown viscosity of Yeonnong1, Miheukchal and Heukjinju was higher than those of tested hybrids, whereas setback viscosity of those hybrids was lower. In cooking properties of milled waxy corn, water absorption and volume expansion rate were high in Yeonnong2 (84.9, 219.3%), Miheukchal (85.9, 211.4%), and Heukjinju (80.9, 203.7%). In the sensory test, the overall preference was significantly higher in Heukjinju and Miheukchal. Thus, Heukjinju, Yeonnong2, and Miheukchal showed good scores in milling yield, cooking properties, and the preference of sensory test. These results will provide fundamental information to extend milled waxy corns usage.Keywords : corn, milling corn, physicochemical, cooking quality

Improvement in commercial scale dry mill corn ethanol production using controlled flow cavitation and cellulose hydrolysis

During commercial-scale dry-mill ethanol production from corn, as much as 6 % of the starch and all of the cellulose remain unconverted. In this study, two methods to improve ethanol production during commercial-scale corn ethanol production were tested that release and hydrolyze these unconverted carbohydrate fractions; controlled flow cavitation (CFC) and enzymatic cellulose hydrolysis. Corn slurry samples were collected from a 379 million liter per year ethanol plant in which a full-scale CFC unit was installed. Samples collected before and after the CFC unit, and after the jet cooker, were compared on three separate occasions. Results showed that CFC reduced the particle size, led to qualitative changes in cell structure, increased total sugars, and reduced total solids after liquefaction. It also led to significant increases in ethanol production and solids conversion during subsequent simultaneous saccharification and fermentation. The effects of CFC alone were greater than those of CFC plus jet cooking, possibly due to the formation of unfermentable products during jet cooking. On average, ethanol production from cavitated samples was 2.2 % greater than from uncavitated samples. Cellulase addition to uncavitated and cavitated samples led to significant 3.2 and 4.3 % increases in ethanol yield, respectively. The electrical energy used for CFC was 1/16th of that in the additional ethanol produced and the ethanol value was more than 38 times the cost of the additional electricity used. This indicates that CFC can both efficiently increase corn ethanol yields and reduce the amount of energy needed to produce it.

A comparison of commercial ethanol production systems from Brazilian sugarcane and US corn

AbstractGlobal biofuels production grew rapidly from 2007 to 2012, led by the United States and Brazil, the world's two largest fuel‐ethanol‐producing systems. In this paper we provide insights into the characteristics of mature Brazilian sugarcane and maturing US dry mill corn ethanol industries. Both systems continue to improve as measured by life cycle data such as total renewable energy produced per unit of fossil energy consumed [renewable energy ratio (RER)]. Sugarcane self‐benchmarking systems showed RER values of 7.0 in 2002 to 9.4 in 2009 as the industry started to switch to mechanized harvesting. The average US RER improved from 1.1 to 1.7 from 2000 to 2010. RERs of 4.4 to 5.5 are observed in corn ethanol plants employing natural gas or corn stover combined heat and power. Ethanol systems configured to produce ethanol and electricity had similar net energy balances (a ratio of net energy produced to energy contained in the fuel). One measure of greenhouse gas (GHG) emissions reductions (biomass use efficiency) compares the effectiveness of displacing carbon from combustion of fossil fuels with renewable carbon. Advanced corn ethanol systems reach higher GHG emission reduction levels compared to sugarcane ethanol by displacing coal‐based electricity. Sugarcane systems achieve double the GHG emissions reductions per unit of harvested land relative to corn ethanol because sugarcane and corn are grown as perennial and annual crops in tropical and temperate climatic zones, respectively. Carbon dioxide capture and storage systems could offer additional GHG emission reductions for both corn and sugarcane ethanol systems. © 2013 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Composition, Rheological and Extrusion Behaviour of Fractions Produced by Three Successive Reduction Dry Milling of Corn

The composition, rheological and extrusion behaviour of three fractions, i.e. coarse (>500 μm), medium-coarse (300–500 μm) and fine (<300 μm), obtained from three successive reduction dry milling of corn was studied. Fractions from different reduction stages vary in composition, pasting and structural characteristics. All the fractions from third reduction stage had higher protein, lipid, ash and b* value while with lower crystallinity and L* value. These fractions also showed higher pasting temperature and lower breakdown viscosity than the fractions from first and second reduction stages. The characteristics of extrudates varied with the composition as well as particle size of the fractions. The fractions with higher lipid and protein content resulted into extrudates with lower water solubility index (WSI) and expansion; however, fine fractions resulted into extrudates with higher WSI and expansion.

Use of Corn Germ Meal in Diets for Pond‐Raised Channel Catfish, Ictalurus punctatus

AbstractCorn germ meal (CGM) is a by‐product of corn milling. On the basis of its nutrient composition and digestibility values, it appears to be a suitable ingredient for use in channel catfish, Ictalurus punctatus, diets. A study was conducted to examine the use of various levels of CGM in diets for pond‐raised channel catfish. Four 28% protein diets containing 0, 15, 25, and 35% CGM were evaluated. Fingerling channel catfish (mean initial weight: 71 g/fish) were stocked into 24, 0.04‐ha ponds at a rate of 14,826 fish/ha. Fish were fed once daily to apparent satiation for a 167‐d growing season. No significant differences were observed in total amount of diet fed, diet consumption per fish, net yield, weight gain, feed conversion ratio, survival, fillet yield, and fillet protein, fat, and moisture concentrations among fish fed diets containing various levels of CGM. Carcass yield decreased linearly as dietary CGM levels increased. Depending on prices, CGM can be used interchangeably with corn gluten feed in channel catfish diets as replacements for corn, wheat middlings, and soybean meal to reduce feed cost.

Fundamental studies on water-washing of the corn ethanol coproduct (DDGS) and its characterization for biocomposite applications

Distiller's dried grains with solubles (DDGS), the main coproduct in the dry mill corn ethanol industry, is finding its way toward a reinforcing filler in polymeric composite applications. In such a journey, thermal stability of DDGS is a critical factor affecting both temperature window of DDGS melt-compounding with polymers and the properties of the final biocomposite material. In this study, DDGS thermal stability was enhanced by washing with water and then used to fabricate biocomposites with Poly(1, 4-butanediol succinate) (PBS). The thermal degradation of DDGS, before and after washing, was studied with thermogravimetric (TG) and derivative thermogravimetric (DTG) analyses, showing up to 50 °C improvement in degradation onset temperature of DDGS after washing. Also, the degradation activation energies for water-washed DDGS were smaller than the respective values for as-received DDGS. Compositional analysis and infrared spectroscopy showed that the water-washed DDGS was higher in protein and fiber content compared to as-received DDGS. As a result of improved thermal stability of DDGS after water-washing, the DDGS burning during melt processing was highly prevented and the biocomposites processed at 160 °C and 190 °C showed constant tensile properties. On the other hand, for as-received DDGS biocomposites the tensile properties decreased as the processing temperature increased. Moreover, the increased fiber content of DDGS after water-washing resulted in biocomposites with higher tensile strength and modulus compared to as-received DDGS biocomposites.

Production, Economic and Financial Results in Vaslui County Agriculture (Case Study at S.A. Agroind Berezeni, Vaslui County, after 20 Years of Activity)

S.A. Agroind Berezeni, Vaslui County was established under the Low nr. 36/1991,according with the Court decision No. 2 from 04.11.1991. Administrative, the company is fromBerezeni Commune located just 5 km from the river Prut, border with Moldova Republic. It was thefirst agricultural unit from Vaslui County with private capital (4.3 billion lei) and second in Moldova,with the activity object: crop production, animal husbandry, processing and capitalization of agrozootechnicalproducts. Based on a good management, the main goal of the company was to design aproduction structures unit that meet the requirements of market economy, aiming to exploit theagricultural potential of the area, both by developing vegetable farms, and those of breeding, puttingemphasis on cattle and sheep for milk and meat. S.A. Agroind Berezeni belonging to the Associationof Cattle Breeders Association Birlad and Husi Eastern Group Association, which unites over 50companies in the agriculture of the county of Vaslui. The unit has a total of 686 associates and has anagricultural area of 3727 hectares, of which arable land 3250. The strategy of development andefficiency of the unit was based on the integration process, by increasing investment both from ownsources and from other sources (loans and attracting European funding by projects), so that currently,is technical and material developed and modernized, appearing new sectors such as: irrigation sector,processing sector for wheat and corn (corn and wheat mill, bakery), milk processing sector, drying andstoring grain sector, dairy sector farm and mechanization modernization, etc. Based on this case study,the authors have proposed to highlight the development opportunities and improvement of agriculturalunits, based on practice an advanced management and marketing, leading to performance andefficiency.

Solvent retention capacity for different wheats and flours evaluation

The baking quality in the sets of both commercial and variety wheat samples (80 and 18 items) and wheat composite flour (standard and 25 blends) was evaluated in terms of the Solvent retention capacity method (AACC 56-11). Composites were prepared from a commercial fine wheat flour and commercial bio-wholemeal flour prepared by milling of common wheat, rye, oat, barleys and corn at substitution levels of 10, 20, 30, 40, and 50%. The commercial wheat quality testing ANOVA revealed the major effect of the sample tested form; the data measured for grain and flour proved to be correlated. Besides, the harvest year affected the baking quality to a greater degree than the growing locality. Within the variety wheat set, the harvest year factor dominated over that of the wheat cultivar one with the exception of the sodium carbonate retention capacity. In the case of the wheat flour substitution by bio-cereal flour types, the added amount of the alternative flour supported only the quantitative change caused by the incorporated cereal in all four retention capacities. &amp;nbsp;

Use of a corn milling product in diets for dairy cows to alleviate milk fat depression

Various diet formulation strategies were evaluated to alleviate milk fat depression using a corn milling product (CMP) that contained approximately 28% crude protein, 34% neutral detergent fiber (NDF), and 12% starch (dry basis). The control diet comprised mostly corn silage, alfalfa silage, corn grain, and soybean meal and contained approximately 22% forage NDF (fNDF), 28% total NDF, and 33% starch. Another diet included 25% CMP that replaced corn grain and soybean meal and contained 27% starch and 33% NDF. Two other diets included 25 or 40% CMP that replaced forage and concentrate and contained 19 and 17% fNDF, 31 and 32% total NDF, and 30 and 28% starch, respectively. Diets were fed to 16 mid-lactation Holstein cows in 4 replicated 4 × 4 Latin squares. Milk fat percentage was low for the control diet (2.9%) but increased to 3.5% when cows were fed the diet with 25% CMP that replaced concentrate. Cows fed diets with 25 or 40% CMP that replaced forage and concentrate also had low milk fat percentages (3.0 and 2.9%, respectively). Intake was lowest for cows fed the control diet. Milk yield was reduced when CMP replaced only concentrate but because of the substantial increase in milk fat, the yield of energy-corrected milk was greater. Calculated energy use (maintenance+milk+body weight change) divided by dry matter intake was similar for the control and for the diet in which CMP replaced only concentrate, but it decreased linearly as increasing amounts of CMP replaced both forage and concentrate. A quadratic equation using the ratio of dietary starch to fNDF was the best predictor of milk fat percentage (ratios >1.4 were associated with reduced milk fat). Overall, CMP was effective at alleviating milk fat depression when it replaced corn grain but not when it replaced forage and concentrate.

Use of dry-milling derived thin stillage for producing eicosapentaenoic acid (EPA) by the fungus Pythium irregulare

This study was to explore the use of thin stillage, a major byproduct in dry milling corn–ethanol plants, for production of eicosapentaenoic acid (EPA) by the fungus Pythium irregulare. Thin stillage contains various compounds that were ideal for fungal growth. Thin stillage concentration and temperature played important roles in fungal growth and EPA production. When 50% thin stillage was used in a stepwise temperature shift culture process, the cell density reached 23g/L at day 9 with EPA yield and productivity of 243 and 27mg/Lday, respectively. The fungal biomass contained 39% lipid, 28% protein, 30% carbohydrate, and 3% ash. The fungal culture also generated a nutrient-depleted liquid by removing organic compounds in the raw thin stillage. The results collectively showed a new use of thin stillage by feeding to the fungus P. irregulare for producing omega-3 fatty acids.

Future Testing Opportunities to Ensure Sustainability of the Biofuels Industry

For the soil and plant analysis community, development and expansion of biofuels will create many opportunities to provide a wide variety of analytical services. Our objective is to explore potential areas where those services could be marketed to support sustainable development of biofuels. One of the first is to provide soil fertility and plant nutrition information for sustainable feedstock production. Chemical, physical, and biological indicators of soil quality should also be monitored and interpreted using tools such as the soil management assessment framework (SMAF) to ensure soil resources can continue to meet global food, feed, and fiber demands as well as the new demands for biofuels. Feedstock sugar profile information will be needed to help manage conversion processes, calculate economic drivers such as the minimum ethanol selling price (MESP), and determine suitability for other bioproducts. There will also be an increasing need to evaluate a variety of coproducts created by corn (Zea mays) milling, soybean (Glycine max Merr.) processing, and the fledgling lignocellulosic conversion processes. For coproducts produced from wet or dry corn milling and dry grind ethanol production, accurate and efficient analysis and digestibility of fiber components [neutral detergent fiber (NDF), acid detergent fiber (ADF), and total dietary fiber (TDF)], amino acids (lysine, trypotophan, and methionine), fatty acids, and minerals (phosphorus and sulfur) will be needed. In addition, a capacity to accurately and rapidly detect contamination by mycotoxins such as aflatoxin, zearalenone, and fumonisisn or the presence of antibiotics such as penicillin or virginiamycin could potentially be important. For the biodiesel industry, methanol concentrations in crude glycerin must be reduced to meet Food and Drug Administration guidelines and quantified to ensure this coproduct is safe for use in livestock feeds. Finally, monitoring for several processes and coproducts associated with pyrolysis, a thermochemical platform for biomass conversion to bio-oils, biochar, and other products will be needed. We conclude that sustainable development of biofuel industries will have many positive benefits for soils, plant, and animal production systems and the analysts who will provide analytical services for monitoring all aspects of the biofuels industry.

Utilization of Corn Hominy as a New Source Material for Thermoplastic Starch Production

Corn hominy or ampok (in local language) is a by-product from corn milling industry. It is about 35% in weight of dry milled kernel. Corn hominy contains a small amount of fibre (7.26%), protein (10.2%), fat (8.12%), and a large amount of starch (63.21%) which could be used as an alternative source for making starch based thermoplastics (STP), hence reducing the use of starch. The aim of this research is to investigate the effects of weight ratio of tapioca to corn hominy as well as the glycerol content in formula compositions on mechanical properties, i.e. tensile strength and elongation at break and thermal properties (Tg and Tm) of corn hominy based thermoplastic. The ratio of tapioca to corn hominy composition varied from 0:100; 25:75; 50:50; 75:25 and the glycerol content varied from 25% to 35 wt%. The blends were melt processed using counter rotating twin screw mixer with the barrel temperature of 120, 130 and 120°C at 60rpm for 5min. It has been observed that using corn hominy as a sole material for making thermoplastic was not feasible. The tensile strength, elongation at break, and glass transition point (Tg) were greatly affected by increasing the tapioca content. Thermoplastics starch produced by extruder was then pressed by a hydraullic press, and this showed good characteristics which signaled by homogenous surface of SEM images. The surface morphology of thermoplastic starch was unchange by increasing the glycerol content and corn hominy ratio. However, higher corn hominy ratio gave smoother surface morphology at the cross section of thermoplastic starch.

The effect of sieve agitators and dispersing agent on the method of determining and expressing fineness of feed materials by sieving

Research in both swine and poultry continue to investigate the optimal particle size for growth and gut health. Although researchers have reported the methods used to determine the particle size of the grain in a study, most reports have not provided details of the actual procedure. Although the standard method suggested adding both agitators and dispersing agents to facilitate the flow of material through the sieves there has been limited research as to whether these modifiers significantly change the particle size value. Researchers, laboratories, and feed mills that analyse samples without sieve agitators or a dispersing agent could overestimate the particle size and underestimate the distribution of the particles of a sample. Two experiments were conducted to determine the effect of adding sieve agitators and dispersing agent to the ANSI/ASAE S319.3 FEB03 ‘Method of Determining and Expressing Fineness of Feed Materials by Sieving’. The first experiment evaluated the effect of sieve agitator use and dispersing agent use on the geometric mean diameter (dgw) and geometric standard deviation (Sgw) of hammermill and roller mill corn samples. Whole corn was ground to produce samples that were classified as either coarse, medium, or fine. The second experiment evaluated the effect of sieve agitators, a dispersing agent, and the combination of agitators with a dispersing agent on dgw and Sgw of hammermill ground corn, wheat, and sorghum. The results of Expt 1 indicated that a decreased (P &lt; 0.01) dgw resulted when agitators were added to the hammermill ground samples while a further decrease (P &lt; 0.01) was observed due to the addition of the dispersing agent. The largest decrease in dgw was observed due to the addition of the dispersing agent. The addition of agitators to the roller mill samples only decreased the dgw of the medium grind sample. The dispersing agent decreased (P &lt; 0.01) the dgw of roller mill samples. The addition of a dispersing agent consistently decreased the dgw of all the ground corn samples as compared with the standard method without modifiers. The results of Expt 2 were consistent with those of Expt 1 in that the addition of the dispersing agent and agitators decreased dgw values and appeared to have an additive effect in both corn and sorghum samples. The addition of a dispersing agent facilitated the flow of product through the sieves. The wider distribution (Sgw) indicated that a greater percentage of material flowed to the smaller sieves. The results of the experiments clearly showed the benefit of adding sieve agitators and a dispersing agent to facilitate the flow of material through the sieves, so that a better estimate of the micron diameter and particle size distribution could be achieved.

The Hawton Gypsum Mill and Developments in 19th-Century Grinding Technology

Hawton Gypsum Mill was formerly part of an extensive complex of gypsum extraction and processing plants that extended over a considerable acreage of south-western Newark in Nottinghamshire (Mill and quarry site, GR SK8014 5070). The sites were interlinked by a standard-gauge tramway, worked by steam locomotives, enabling the output of the quarries to be matched to the capacities of the mills.The Hawton Mill was attached to its own quarry, the later of which appears to have been in production since the 1840s. Although the evidence is inconclusive, there may have been a processing mill on the site from the beginning. However, the present mill was probably completed in the second half of the 19th century, possibly after Messrs Cafferata became owners of the site.The brick building that enclosed the milling machinery followed the local vernacular tradition of industrial buildings. The plant contained within the building, although specifi cally intended for gypsum reduction, consisted of an installation characteristic of corn milling. This adoption of corn milling technology to refi ne gypsum is a particularly signifi cant development in the gypsum industry's history, and there were several similar plants in operation locally until the closing decades of the 20th century.In addition to the interest that attaches to the use of such machinery for gypsum processing, the mill machinery embodies two further important features of wider consequence for the study of stone milling technology. It represents a type of milling plant that had become virtually standard throughout the cereal milling trade after about 1830. This was the layshaft mill, which used a horizontal main drive shaft carrying several sets of bevel gearwheels, each driving an individual pair of stones. The arrangement of the stones was thus linear as opposed to the circular confi guration of stones driven by the great wheel and its upright shaft, the pattern commonly adopted in the 18th century.The newer type of mill was built entirely of iron, the product of the engineering works, whereas the older upright shaft mill was a traditional millwright's construction, fabricated on site, largely from timber. The engineer-built, all-iron mill lent itself to modular construction. Increasingly, agricultural and other engineering firms offered such mills as catalogue products available as single stone units or multiples thereof. Hawton was clearly of this form with standard elements bolted together in series to create a twin line each of eight stone sets.The mill with its machinery survived until recently and was surveyed in the year 2000 by Structural Perspectives Ltd, acting as subcontractors to the Archaeology Service of Nottingham County Council. As it stood at the time of the survey, the Hawton Gypsum Mill was reduced to a single block standing isolated at the edge of the recently filled quarry. The building had been heavily vandalized and fire damaged but nevertheless remained substantially intact. The associated ancillary process and other buildings shown on earlier maps and photographs had been recently demolished.

John Rennie, mechanical engineer

While John Rennie is now remembered as the leading civil engineer of his day, his contributions to mechanical engineering are largely forgotten. With his iron gearing and shafting, he had probably developed corn milling as far as was possible until the advent of roller milling in the 1880s. We have few details of the machinery he installed at places such as Kirkstall forge and the dockyard at Copenhagen and few drawings of his mechanical inventions have survived to enable us to judge them and compare them with others. If they had, perhaps Rennie might be remembered alongside his contemporaries such as Joseph Bramah and Henry Maudslay. Archives show that he was extensively involved in this industry but few details of his work remain. This, sadly, is also true of so much of his mechanical engineering and prevents his work in this field becoming better recognised. His major achievement in mechanical engineering was his use of steam power in so many applications for civil engineering.