Microbiology of Retail Asian Stirfry Packs

Sonja Winkler, IHD Knoxfield, (03) 9210 9222

Handling and processing of fresh horticultural produce increases the risk of microbial contamination and changes to the products' natural microflora. Concerns for the food safety of prepared salad and vegetable mixes resulted in the microbiological evaluation of an Asian stirfry mix during its shelf-life.

Processing was conducted at 4°C using commercial handling procedures. The processed vegetables were sanitised in a 100ppm chlorine solution (pH=8; calcium hypochlorite 650g/kg active ingredient) for 5 minutes and rinsed in potable water for 5 minutes. The washing solutions were cooled to 4°C. The produce (350g) was packaged into modified atmosphere bags and stored at 4°C or 8°C for 10 days to determine the microbiological status at temperatures normally encountered during distribution and marketing. Produce was assessed on days 0, 3, 7 and 10 for total plate count (aerobic bacteria) and the presence of yeast and moulds.

At all assessment times, total plate counts were greater for packages stored at 8°C than those stored at 4°C. The differences between the two temperatures and between removal times were significant. Unacceptable levels of aerobic bacteria were only observed after 10 days storage at 8°C. Yeast and mould counts did not increase with storage temperature or time.

The results highlight the need for good hygiene practices and temperature management throughout distribution and marketing to ensure product quality and safety for consumers.

This project was funded by Oriental Merchant and the Rural Industries Research and Development Corporation.

Bamboo in Victoria

Ross Clarke, DNRE Agribusiness Initiative, (03) 9210 9222

There has been a growing interest in recent times in the possibility of developing a bamboo industry in Victoria. An addition to this interest was an offer from the Hiroshima prefecture of Japan of "moso" seeds to Victoria as a goodwill gesture. "Moso" is grown mainly for shoots in Japan. According to the Victorian Government Office in Japan, the domestic production of "moso" bamboo has been on the decline for the last twenty years. It declined from 44,160,000 bundles in 1985 to 14,711,000 in 1997. There has been an increasing amount of imported shoots from China, Taiwan and Singapore.

There are a few Victorian growers that are already growing moso and other bamboo types to supply domestic market needs. They are looking to expand their communication networks and to investigate markets to grow the industry. In recent discussions, it was decided that "moso" (a spreading type of bamboo) was well suited to Victorian production as opposed to the clumping varieties grown in the northern states. The industry would be keen to work in with the National Bamboo Project (Queensland) and key industry associations.

For further information, contact Mandy Chew (03) 9210 9222.

Taro (Colocasia esculenta)

Taro also known as "wu tau" in Chinese and "khoai môn" in Vietnamese is a perennial herbaceous plant growing 1-2m tall with underground tubers. Its leaves are light green, elongated and heart shaped 30-50cm long borne on long petioles from the ground.

The edible portion of the plant is the tuber. Depending on the variety, the tubers vary in shape but are roughly spherical from 2.5-23cm in diameter. They are brown in colour. The hairy skin has fine, dark rings that encircle it at regular intervals. When cut, the white flesh is flecked with purple.

These tubers contain nearly: 20-35% starch 0.59-0.17% calcium 1.5-3% protein 0.113-0.274% phosphorus 0.47-0.68% fat 0.0042-0.005% iron

Production
Taro requires high temperatures (25-35°C), a season of a minimum of 200 days and lots of water during growth. It is frost sensitive.
Sow tubers into 15cm deep trenches, 40cm apart and cover with 5-8cm soil. Plant cuttings can also be used. It is often grown alongside irrigation ditches or at the edge of fields and plots. Harvest occurs when the leaves yellow and are almost dead. Stem cuttings can also propagate taro. The average 1997 yield around the world is 6.2 tons/ha.
Taro is grown commercially in NSW, Qld and the NT. Melbourne is supplied from Qld and Fiji.

Preparation
Small taro may be baked or boiled whole. Larger ones should be peeled and chopped. Handle with gloves if necessary.

Cooking
All parts of the taro contain calcium oxalate which can cause allergic reactions in some people in its raw form. It must therefore be cooked before it can be eaten safely. Taro starch is extremely fine grained and the texture is smoother and creamier than other roots, tubers and grains. The Cantonese say taro affects the stomach. In moderation, it aids digestion but too much causes indigestion. Each individual has to find his/her own limit!
Taro can substitute for potatoes in any recipe. It can be boiled, baked, braised, mashed, sautéed, deep-fried or stewed.
Leaves and stems are edible and considered to be more nutritious and better flavoured than the tuber. Leaves are best eaten when young and should be boiled twice discarding the water to remove the acrid flavour. They can be puréed like spinach. Stems can be cut into pieces, peeled and boiled.

Website
Asian Vegetables Thesaurus
Agriculture Victoria, IHD Knoxfield
http://www.dpi.vic.gov.au/trade/asiaveg/thes-62.htm

Pick from the RIRDC book shelf

Food Distribution in China and Hong Kong - Market Profile and Directory Kelvin Fahey, SIRA International
RIRDC Research Paper 94/6
$60 ($6 p&h) 194 pages

Outlines the food distribution structure of China and Hong Kong, basic statistics on food market indicators, a summary of government food import regulations and customs procedures, and a directory of major food wholesalers and importers.

The book can be purchased from
Rural Industries Research and Development Corporation (RIRDC)
P.O. Box 4776, Kingston, ACT 2600, Phone: (02) 6272 4819, Fax: (02) 6272 5877
Webpage: http://www.rirdc.gov.au/

For more RIRDC publications see our first 'Asian Foods' Newsletter.