Phenolics in sugar cane juice : potential degradation by hydrogen peroxide and Fenton's reagent

The presence of colour in raw sugar plays a key role in the marketing strategy of the Australian raw sugar industry. Some sugars are relatively difficult to decolourise during refining and develop colour during storage. A new approach that might result in efficient and cost-effective colour removal during the sugar manufacturing process is the use of an advanced oxidation process (AOP), known as Fenton oxidation, that is, catalytic production of hydroxyl radicals from the decomposition of hydrogen peroxide using ferrous iron. As a first step towards developing this technology, this study determined the composition of colour precursors present in the juice of cane harvested by three different methods. The methods were harvesting cane after burning, harvesting the whole crop with half of the trash extracted and harvesting the whole crop with no trash extracted. The study also investigated the degradation at pH 3, 4 and 5 of a phenolic compound, caffeic acid (3,4–dihydroxycinnamic acid), which is present in sugar cane juice, using both hydrogen peroxide and Fenton’s reagent. The results show that juice expressed from whole crop cane has significantly higher colour than juices expressed from burnt cane. However, the concentrations of phenolic acids were lower in the juices expressed from whole crop cane. The main phenolic acids present in these juices were p-coumaric, vanillic, 2,3–dihydroxybenzoic, gallic and 3,4–dihydroxybenzoic acids. The degradation of caffeic acid significantly improved using Fenton’s reagent in comparison to hydrogen peroxide alone. The Fenton oxidation was optimum at pH 5 when up to ~86 % of caffeic acid degraded within 5 min.

Phenolics in sugar cane juice : potential degradation by hydrogen peroxide and Fenton’s reagent

The presence of colour in raw sugar plays a key role in the marketing strategy of the Australian raw sugar industry. Some sugars are relatively difficult to decolourise during refining and develop colour during storage. A new approach that might result in efficient and cost-effective colour removal during the sugar manufacturing process is the use of an advanced oxidation process (AOP), known as Fenton oxidation, that is, catalytic production of hydroxyl radicals from the decomposition of hydrogen peroxide using ferrous iron. As a first step towards developing this technology, this study determined the composition of colour precursors present in the juice of cane harvested by three different methods. The methods were harvesting cane after burning, harvesting the whole crop with half of the trash extracted and harvesting the whole crop with no trash extracted. The study also investigated the degradation at pH 3, 4 and 5 of a phenolic compound, caffeic acid (3,4–dihydroxycinnamic acid), which is present in sugar cane juice, using both hydrogen peroxide and Fenton’s reagent. The results show that juice expressed from whole crop cane has significantly higher colour than juices expressed from burnt cane. However, the concentrations of phenolic acids were lower in the juices expressed from whole crop cane. The main phenolic acids present in these juices were p-coumaric, vanillic, 2,3–dihydroxybenzoic, gallic and 3,4–dihydroxybenzoic acids. The degradation of caffeic acid significantly improved using Fenton’s reagent in comparison to hydrogen peroxide alone. The Fenton oxidation was optimum at pH 5 when up to ~86% of caffeic acid degraded within 5 min.

Dancing between diversity and consistency : refining assessment in postgraduate degrees in dance

This publication is the culmination of a 2 year Australian Learning and Teaching Council's Project Priority Programs Research Grant which investigates key issues and challenges in developing flexible guidelines lines for best practice in Australian Doctoral and Masters by Research Examination, encompassing the two modes of investigation, written and multi-modal (practice-led/based) theses, their distinctiveness and their potential interplay. The aims of the project were to address issues of assessment legitimacy raised by the entry of practice-orientated dance studies into Australian higher degrees; examine literal embodiment and presence, as opposed to cultural studies about states of embodiment; foreground the validity of questions around subjectivity and corporeal intelligence/s and the reliability of artistic/aesthetic communications, and finally to celebrate ‘performance mastery’(Melrose 2003) as a rigorous and legitimate mode of higher research. The project began with questions which centred around: the functions of higher degree dance research; concepts of 'master-ness’ and ‘doctorateness’; the kinds of languages, structures and processes which may guide candidates, supervisors, examiners and research personnel; the purpose of evaluation/examination; addressing positive and negative attributes of examination. Finally the study examined ways in which academic/professional, writing/dancing, tradition/creation and diversity/consistency relationships might be fostered to embrace change. Over two years, the authors undertook a qualitative national study encompassing a triangulation of semi-structured face to face interviews and industry forums to gather views from the profession, together with an analysis of existing guidelines, and recent literature in the field. The most significant primary data emerged from 74 qualitative interviews with supervisors, examiners, research deans and administrators, and candidates in dance and more broadly across the creative arts. Qualitative data gathered from the two primary sources, was coded and analysed using the NVivo software program. Further perspectives were drawn from international consultant and dance researcher Susan Melrose, as well as publications in the field, and initial feedback from a draft document circulated at the World Dance Alliance Global Summit in July 2008 in Brisbane. Refinement of data occurred in a continual sifting process until the final publication was produced. This process resulted in a set of guidelines in the form of a complex dynamic system for both product and process oriented outcomes of multi-modal theses, along with short position papers on issues which arose from the research such as contested definitions, embodiment and ephemerality, ‘liveness’ in performance research higher degrees, dissolving theory/practice binaries, the relationship between academe and industry, documenting practices and a re-consideration of the viva voce.

Development of descriptor tools for the characterization of Australian sugar mill evaporator scale

Cleaning of sugar mill evaporators is an expensive exercise. Identifying the scale components assists in determining which chemical cleaning agents would result in effective evaporator cleaning. The current methods (based on x-ray diffraction techniques, ion exchange/high performance liquid chromatography and thermogravimetry/differential thermal analysis) used for scale characterisation are difficult, time consuming and expensive, and cannot be performed in a conventional analytical laboratory or by mill staff. The present study has examined the use of simple descriptor tests for the characterisation of Australian sugar mill evaporator scales. Scale samples were obtained from seven Australian sugar mill evaporators by mechanical means. The appearance, texture and colour of the scale were noted before the samples were characterised using x-ray fluorescence and x-ray powder diffraction to determine the compounds present. A number of commercial analytical test kits were used to determine the phosphate and calcium contents of scale samples. Dissolution experiments were carried out on the scale samples with selected cleaning agents to provide relevant information about the effect the cleaning agents have on different evaporator scales. Results have shown that by simply identifying the colour and the appearance of the scale, the elemental composition and knowing from which effect the scale originates, a prediction of the scale composition can be made. These descriptors and dissolution experiments on scale samples can be used to provide factory staff with an on-site rapid process to predict the most effective chemicals for chemical cleaning of the evaporators.

Fouling of tubular ceramic membranes during processing of cane sugar juice

This paper examines the fouling characteristics of four tubular ceramic membranes with pore sizes 300 kDa, 0.1 μm and 0.45 μm installed in a pilot plant at a sugar factory for processing clarified cane sugar juices. All the membranes, except the one with a pore size of 0.45 μm, generally gave reproducible results through the trials, were easy to clean and could handle operation at high volumetric concentration factors. Analysis of fouled and cleaned ceramic membranes revealed that polysaccharides, lipids and to a lesser extent, polyphenols, as well as other colloidal particles cause fouling of the membranes. Electrostatic and hydrophobic forces cause strong aggregation of the polymeric components with one another and with colloidal particles. To combat irreversible fouling of the membranes, treatment options that result in the removal of particles having a size range of 0.2–0.5 μm and in addition remove polymeric impurities, need to be identified. Chemical and microscopic evaluations of the juices and the structural characterisation of individual particles and aggregates identified options to mitigate the fouling of membranes. These include conditioning the feed prior to membrane filtration to break up the network structure formed between the polymers and particles in the feed and the use of surfactants to prevent the aggregation of polymers and particles.

Green cane impact on sugar processing : ISSCT process workshop 2008

The ISSCT Process Section workshop held in Réunion 20–23 October 2008 was attended by 51 delegates from 10 countries. The theme was Green cane impact on sugar processing. The workshop provided a valuable and timely opportunity to review and discuss the impact on factory operations and performance from a green cane supply that could include significant levels of trash. It was particularly relevant to those mills that were considering options to boost their biomass intake for increased co-generation capacity. Several of the speakers related their experiences with processing ‘whole of crop’ cane supplies through the factory. Speakers detailed the problems and increased losses that were incurred when processing cane with high trash levels. The consensus of the delegates was that the best scenario would involve a cane-cleaning plant at the factory so that only clean cane would be processed through the factory. The forum recommended that more research was required to address the issues of increased impurities in the process streams associated with high trash levels. Site visits to the two factories and a cane-delivery station were arranged as part of the workshop.

Formation of thermodynamically unstable calcium oxalate dihydrate in sugar mill evaporators

Calcium oxalate (CaOX) is the most intractable scale component to remove in sugar mill evaporators by either mechanical or chemical means. The operating conditions of sugar mill evaporators should preferentially favour the formation of the thermodynamically stable calcium oxalate monohydrate (COM), yet analysis of scale deposit from different sugar factories have shown that calcium oxalate dihydrate (COD) is usually the predominant phase, and in some cases is the only hydrate formed. The effects of trans-aconitic, succinic and acetic acids, all of which are present in sugarcane juice, and ethylenediamine tetraacetic acid disodium salt (EDTA) on the growth of CaOX crystals have been examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA). trans-Aconitic acid, which constitutes two-thirds of the organic acid component in sugarcane juice, in the presence of sugar resulted in the formation of COD and COM in a 3:1 ratio. EDTA was the most effective acid to promote the formation of COD followed by trans-aconitic acid, then acetic acid and lastly succinic acid.