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The present Australian method of providing economic incentive for maintenance or expansion of her dairy industry could easily lead the New Zealand Government to include her amongst the countries charged with dumping butter on the United Kingdom market. The two-pool scheme would greatly reduce the likelihood of this charge. The same scheme has previously been advocated as the best way of reconciling the interests of the Australian producer and consumer.
When tinned surfaces are electrically coupled to bare copper in milk handling equipment cleaned with orthodox detergents not only does the tin corrode more readily than when there is no coupling with copper but there is a marked increase in the build-up of milkstone deposits on the surface of the tin. Evidence is produced for the view that electrolytic action is important in the formation of milkstones in milking machinery.
Cheddar cheese had developed a "fermented" flavour defect after 6 months' storage contained elevated levels of ethanol, ethyl acetate and ethyl butyrate. This cheese was also high in moisture (39%) and contained high levels of Candida sp.
A bacteriological scheme for evaluating and comparing standards of hygiene at cheese factories is proposed. The scheme entails the application of simple bacteriological tests to samples obtained from each cheese factory. An advisory standard is set for each test and points are allotted to samples according to their compliance with this standard. Quality indices, representing the total score obtained by each sample, are then calculated. An overall factory index is then calculated and report forms, containing the results and appropriate advisory remarks, are sent to the factory.
The key innovation that was to define the commodity cheesemaking industry for decades, not only in New Zealand but also world-wide, occurred from 1960 onwards, when the essentially manual cheesemaking industry was mechanised and automated. Driven by the need to reduce cost, increase scale and reduce labour inputs and the need for greater product uniformity and consistency, the cheesemaking process underwent significant changes with respect to the equipment and processes used. Those changes maximised milk processing capacity and minimised labour input while maintaining, and in many cases enhancing, product quality. As a consequence of this revolutionary approach to cheesemaking, cheese plants in New Zealand became larger and fewer, and the companies that operated them amalgamated.
Although the past 40 years have not seen the same magnitude of change in technology that defined the mechanisation of the cheesemaking process in the decade preceding 1970, continued innovation has seen significant refinements in the way in which cheese is made by the mechanised process that have led to further reductions in cost, increased scale efficiencies, greater product uniformity and consistency and fewer labour units being required. Recent published literature and patent applications would suggest that the next innovative steps in the evolution of cheesemaking in the 21st Century will be the development of new ways of making cheese together with the continued refinement of the traditional processes that we have seen to date.
As an example, in February 2008, the New Zealand dairy industry commercialised an innovative mozzarella process that is an alternative approach to traditional mozzarella manufacture. Unique to New Zealand, this process produces a functionally acceptable product in a shredded format directly off the line in less time than the traditional process.
Authors: R.J. Marschke, D.E.J. Nickerson, W.D. Jarrett and J.R. Dulley
The addition of Maxilact, a commercially available β-galactosidase extract of the yeast Kluyveromyces lactis, to cheese milk resulted in increased proteolytic breakdown in the cheese. Mild heat treatment of the Maxilact completely inactivated the β-galactosidase but had no effect on contaminating protease(s) which exhibited maximum activity at about pH 6.0. This heat treated extract caused a similar increase in protein degradation in cheese to that caused by untreated Maxilact. Maxilact caused no change in starter numbers with Streptococcus cremoris ML1 or E8, while the growth of S. Cremoris AM2 and EB6 was considerably inhibited. The heat-treated Maxilact caused some acceleration in the ripening rate of cheese, with no detrimental effect on cheese composition or flavour development.
A method of analysis of the volatile components from cheese was developed to reflect the natural profile of its aroma. This involved an effective sample collection technique to trap the volatiles, using liquid nitrogen, prior to gas chromatographic analysis and mass-spectral identification. Optimum conditions for volatile component collection were determined. Reproduceability was good. Calibration of the system showed a linear relationship between log peak area and log concentration for selected compounds across the gas chromatographic profile. The method was used to examine volatile components from cheddar cheese stored for twenty months. The method is easy to use, efficient, accurate and faster than other analysis techniques such as distillation and subsequent gas chromatography.
A collaborative trial involving 13 dairy laboratories was conducted to determine the total organic nitrogen (TN) content of samples of skim milk powder with a view to using such a material as a protein reference. A dry basis reference value of 6.61% TN with confidence limits of 0.10% TN (reproducibility) and 0.054% TN (repeatability) was obtained for the Kjeldahl-based instruments. Comparison of this value with a value determined from limited data using the Dumas technique was made. A higher mean value for the Dumas method was found. The methodology can be used to develop reference materials for a variety of protein-rich dairy products.
A continuous commercial-scale cheddaring machine is described. It consists of a drainage vat and a system of conveyors for converting granular curd into fused slabs. On the last conveyor the slabs are subjected to compression which causes the curd to flow and ensures a pronounced fibrous structure. The machine is made almost entirely of stainless steel and is hydraulically driven. It has a throughput of about 6,000 lbs of cheese per hour. Trials with commercial-size batches of curd have shown that the machine will produce well cheddared curd within a wide range of required compositions.
Authors: M.P. Thomas, M.C. Broome, A.J. Hillier and G.R. Jago
The pathway forming acetate from pyruvate was saturated at lower levels of acetate in Streptococcus lactis subsp. Diacetylactis in Str. lactis C10 or Str. cremoris HP. The activity of the enzyme forming acetate was compared in Str. lactis C10 and Str. lactis subsp, diacetylactis DRC2, and it was shown that pyruvate decarboxylase, lipoate acetyl transferase and acetate kinase were more active in Str. lactis C10 than in Str. lactis subsp. diacetylactis DRC2. These differences are discussed in terms of the ability of Str. lactis subsp. diacetylactis to produce more acetoin and diacetyl than Str. lactis or Str. cremoris.
A comparison has been made of the effects on cheese quality of using paired single strain starters as against a commercial mixed starter in use in many Queensland cheese factories. The grading results, at 3 weeks and at two months, for sixteen paired batches of cheese showed that the single-strain cultures produced the better cheese. Grading results from a factory which made each day one of two vats of cheese with the mixed culture and one vat with single strains confirmed this finding. The starter flora survived longer in the experimental cheese than in cheese made under commercial conditions. Streptococcus diacetiactis was the predominant lactic species surviving in experimental cheese made with mixed culture. This species outlived Streptococcus cremoris. All the experimental cheese manufactured showed little contamination by yeasts, moulds and lactobacilli. There did not appear to be any relation between the total number of organisms (on nutrient agar or T.Y.L.B. agar) and the cheese grades. In the cheese made with single strains a low concentration of bacteriophage for one or other strain was always present.
Fourteen films consisting of cellophanes, low and high density polyethylenes and polypropylenes were evaluated in an accelerated storage trial as alternatives to vegetable parchment for wrapping butter. The storage conditions were chosen to simulate those prevailing in the export situation.
The results showed that the grade of the surface of the butter was adversely affected in a number of cases in comparison with a parchment control. With some films, however, the grade of the butter was equal to or better than that with the parchment. The loss in grade was not due to surface oxidation and none of the films tested promoted surface oxidation as measured by Peroxide Value.
With most of the films tested there was an increase in mould count of the butter during storage but in only one case was this statistically significant. With two films the increase in mould count was accompanied by visible mould spots.
Authors: J.M. Scott, L.O. Smith, D.G. Dunsmore and E. Belinda Dettmann
Three systems designed for cleaning refrigerated farm bulk milk tanks were compared in a field trial. These were an automatic cleansing-in-place (CIP) unit, a high-pressure spray unit and manual cleaning. The efficiency of the systems was compared by bacteriological examinations of rinse samples, by visual assessment of the deposits using an ultra-violet light, and by economic and practical assessments.
Bacteriological performance of the three cleaning systems was satisfactory, with automatic CIP and manual cleaning showing slightly superior performance to high pressure cleaning. Visual inspections showed a similar result, more soil accumulating with high pressure cleaning than with other systems.
The automatic CIP unit tested was found to save considerable labour resources and is a satisfactory substitute for manual cleaning of refrigerated farm bulk tanks. However, the economic results show that labour saving advantages of both mechanical systems were largely offset by the capital costs involved.