K.Y. Cho and D.V. Radford

Lentinus edodes (shiitake mushroom) is a highly valued produce with great potential for export. In the last decade, Japan, previously a major producer of shiitake, has had to import the mushroom from overseas because of a shortage of logs of hardwood trees that are used as the substrate. The alternative "synthetic sawdust log" method widely used in developing nations is by Western standards, small scale and non-intensive. The quality of the mushroom is inferior to those using the "log method". Furthermore, the quality can vary considerably because of the difficulty of maintaining substrate consistency.

Australia, because of its unique geographical position and reputation for producing clean primary products, is well placed to compete for the highly lucrative export market. On the negative side, Australia is short of the appropriate hardwood, the natural substrate for growing shiitake. Its labour costs are also high compared to most developing countries.

The project "The optimisation of method for cultivating exotic mushrooms, with particular reference to shiitake" is an extension of an innovative method developed earlier in the University of Sydney using a novel substrate that is in plentiful supply in Australia.

The three-year study was funded by the Rural Industry Research and Development Corporation (RIRDC), Horticultural Research and Development Corporation (HRDC), the mushroom industry and the University of Sydney.

The first stage of the project was directed to the improvement of the traditional bag cultivation system by substrate formulations, strain selection, use of supplementation in cold shock treatment and the mechanisation of the cultivation process.

The second stage aimed to modify the substrate into suitable compost to allow non-aseptic conditions to be used for the cultivation process. This would facilitate bulk material handling and enable Australian mushroom growers to cultivate shiitake using a cultivation method similar to that of Agaricus bisporus.

Results obtained showed that shiitake of good quality could be grown on an alternative substrate other than the traditional log or sawdust of hardwood trees. There is a substantial saving in production costs by fine tuning the factors used in cultivation as listed earlier. Another significant finding is that the substrate can be converted into a form which allows the use of non-aseptic conditions for the cultivation process. Preliminary studies indicate that the alternative substrate is also suitable for cultivating a wide range of wood rotting mushrooms, some of which are of medicinal importance.

The University, on behalf of the granting bodies, has taken out a provisional patent. It is hoped that further trials on a bigger scale would help to realise its commercial potential on a firm basis.

The full report on this project will be published by RIRDC in the next month or so.

Dr. K.Y. Cho Department of Microbiology University of Sydney NSW 2006 Fax: (02) 935l 4571 E-mail: kcho@microbio.usyd.edu.au

DIVERSIFYING ASIAN VEGETABLE MARKETS
(Project US-153A)

Graeme Thomson

The investigation and development of domestic and export market opportunities for fresh whole, minimally processed and processed Asian vegetable products are the main objectives of this project. A rapidly expanding Asian vegetable industry in Australia is increasing its exports and Australian supermarkets have identified Asian vegetables as a new growth area. In order that the full potential of these opportunities is realised, considerable research and development is required to deliver a quality product.

This project, which is now jointly funded by RIRDC and Horticultural Research and Development Corporation, aims to diversify marketing opportunities by improving vegetable quality and expanding the available product range. As background in establishing the viability of market potential, growers' gross margins were determined for Chinese cabbage (Brassica rapa var. pekinensis), baby Shanghai pak choy (Brassica rapa var. chinensis), Chinese chives (Allium tuberosum), choy sum (Brassica rapa var. parachinensis), daikon radish (Raphanus sativus), Chinese spinach (Amaranthus gangeticus), garland chrysanthemum (Chrysanthemum coronarium), water convolvulus (Ipomea aquatica) and Japanese pumpkin (Cucurbita moschata, C. maxima). In addition, Sydney and Melbourne market prices were reviewed.

Issues of Asian vegetable quality are not well documented. Quality descriptor language manuals for five Asian vegetables (Chinese broccoli, Chinese cabbage, Chinese flowering cabbage, pak choy and Shanghai pak choy) were prepared to clarify aspects of desired quality for customers and consumers at all stages of the handling and sales chain. These documents are similar to the Australian Horticulture Corporation's Apple Product Descriptor Language. The five Asian vegetables selected were those identified as the top five Asian vegetables for supermarket requirements.

Quality is achieved when customer requirements are consistently met. This is only possible when the requirements are understood and agreed upon by both suppliers and customers. The documents prepared for this project clearly describe physical traits, product disorders and handling issues which can be used to define the customer's requirements. Each vegetable displays many variations in quality characteristics. Quality descriptor language provides the basis for the development and discussion of product specifications that are understood and accepted by everyone within the product marketing chain.

Access to markets for fresh Asian vegetables is limited by the perishable nature of these products. As soon as a vegetable is harvested it starts to deteriorate. Its water source is removed and assimilation of carbohydrates becomes restricted. The aim of postharvest research is to prolong the product's life so that the vegetable remains in top condition for use by the end consumer. This means that vegetables must survive extended periods in the handling and marketing chain, especially if they are being exported. On the domestic scene, if longer postharvest life can be achieved then marketing of the product can become more flexible and profitable.

Development of packaging and associated cooling requirements for extension of postharvest life was the main component of the project. Fresh plant products use oxygen and their food reserves during respiration to produce the energy required to keep them alive. Temperature is one of the most important factors affecting rate of respiration. Lower storage temperatures help to reduce respiration and lower consumption of finite food reserves, thereby preserving the product's life.

However, the gaseous atmosphere around the harvested plant produce can also be used to regulate respiration rates. If oxygen levels are lowered and carbon dioxide increased, the rate of respiration can be reduced. Modified atmosphere packaging (MAP) uses the product's natural production of CO2 and consumption of O2 to help create a gaseous environment wherein the respiration rate is lowered.

In combination with low temperatures and high humidity, modified atmosphere packaging was successfully used to maintain the quality of Asian vegetables during distribution and storage phases. MA packages for use at 0oC were developed for Shanghai pak choy, Chinese broccoli, choy sum and hot mint. Packaging was developed in conjunction with a commercial industry partner and package volumes reflected local supermarket needs. Compared to air, product held in a modified atmosphere stored longer, generally had superior appearance at out-turn, was greener and less affected by storage rots. Current MA work is focused on carton liners for use with snake beans, perilla, Thai basil and coriander.

The project examined product diversification by considering two means of minimal processing. Minimal processing is an innovative way of adding value to fruit and vegetables. The perception by consumers of convenient, ready to use products is making these commodities increasingly popular. There are many different fruit and vegetable preparations available in the market place. Vegetable mixes include basic stir-fry mixes but few to date have contained traditional Asian vegetables.

There is very little information available on the response of Asian vegetables to physical preparation or minimal processing and how they should be packaged and handled. Experiments in this project tested post-processing behaviour and determined packaging requirements for a range of novel Asian stir-fry mixes. MAP for a stir-fry mix with 8 vegetable components was developed for retail sale. At 4°C, shelf life is at least 8 days.

A consistent aim throughout the project has been improvement of postharvest practices to deliver fresh Asian vegetables in optimum condition to consumers. For export markets this can be difficult to achieve because long journeys by sea often necessitate the use of complex packaging and storage requirements for live, fresh product. The value of whole, fresh vegetables often does not justify the use of quicker, but far more expensive, air transit.

Processing procedures have been developed for salted Chinese cabbage, a product that is physiologically dead and therefore more simple than fresh produce to store and handle for export. It is produced by 'value-adding' and this brings additional benefits to the Australian economy.

Australia currently produces Chinese cabbage of high quality but the procedures required for processing into salted product were not previously fully elucidated. Salting trials undertaken in this project were in conjunction with a consultant from the Australian pickling industry (GeeVee Pickles Pty Ltd). Trials were needed to determine use of appropriate temperature and pressure during preparation. Quality assessment (including comment on product sent to Japan) considered appearance, taste and texture.

Temperature and pressure treatments during preparation were found to have important effects on both appearance and taste. The cultivar 'Matilda' was preferred because of its yellow coloured heart.

The salted Chinese cabbage produced by this protocol conforms to Japanese market requirements and trial export shipments were well received. The cabbage was assessed at the stage where it could be used immediately, or further processed and fermented to produce a product such as kimchi.

The salting protocol developed in this project puts the Australian food processing industry in a position to capitalise on recognised export opportunities to Asia for minimally processed, salted product.

A more detailed full report for the first stage of this work will be published by RIRDC soon.

Institute for Horticultural Development Agriculture Victoria, Knoxfield Private Mail Bag 15 Ferntree Gully Delivery Centre Victoria 3156, AUSTRALIA Tel: (03) 9210 9222 Fax: (03) 9800 3521 Email:graeme.thomson@nre.vic.gov.au

UPDATE ON RIRDC ASIAN FOODS PROGRAM -
February 1999

Jeff Davis, General Manager, Research, and Asian Foods Program Manager, RIRDC

It is pleasing to see that the Newsletter is now well into the second year. As far as I can tell most readers are very positive about the focus and format of the Newsletter. However, it is always difficult to gauge this through casual discussions with people. As a result of discussions between Mandy, Wendy and me, we have decided that it is about time to look for a more comprehensive set of readers' views. Enclosed with this Newsletter is a survey form, which we would very much appreciate it if all readers could spend a little time filling out and returning in the post paid envelope, to Mandy. We hope the results of this survey will provide us with a clearer picture of all readers' views and also whether there are some changes in emphasis or focus, which can be made to improve the Newsletter.

Several projects have recently been completed or are about to finish (some have been highlighted in this Newsletter). RIRDC have nearly finished assessing these and will shortly progress them to the publication stage. We will publicise these in the Newsletter, however, the reports are posted to the RIRDC Home page not pages as soon as the decision is made to publish them. If people are interested in advanced information they could check the home page regularly for these, the address is http://www.rirdc.gov.au/.

RIRDC has introduced an annual 'Research in Progress Report', which is provided by each project research group in about June each year. The full set of these for all 21 RIRDC R&D programs is placed on the RIRDC Home Page. In addition the Asian Foods sub-set is printed and is available free of charge. This report includes a brief summary, about 200 words, for continuing projects as at June 30, and a one-page summary of all projects completed during the previous financial year. Many people have received a copy via different workshops etc during the past few months, however, if anyone else would like a copy, please give me a call and I can arrange for one to be sent.

As I have emphasised in previous Newsletters budget cuts two years ago have had a significant lagged effect on the Asian Foods program. The last of this impact will disappear with the new project funding for the 1999/2000 financial year, that is, the set of projects we will consider during the next month. The next call for new proposals, which will occur with the release of our Program Prospectus in late July 1999, will return to the usual level of funding for new projects. I would therefore encourage those with potential good ideas for Asian Foods R&D to start thinking about these now and ensuring industry groups are also involved in the evolution of these ideas.

Finally, RIRDC has commissioned the Centre for International Economics to undertake a benefit/cost evaluation of past Asian Foods projects and to use this, plus industry focused workshops, to develop a five year R&D plan for the program. We hope that all areas of this diverse industry will be able to participate in this process. If you would like further details please do not hesitate to contact me.

Dr. Jeff Davis RIRDC PO Box 4776 Kingston ACT 2604 Tel: (02) 6272 4152 Fax: (02) 6272 5877 Email: jeffd@rirdc.gov.au Website: http://www.rirdc.gov.au/

 

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