11. Post-harvest equipment

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11.1. Basic equipment for practical field use and troubleshooting

Specialists and extension workers are often required to assist growers and marketing organizations by making decisions about crop maturity and produce storage or distribution. At other times, these same workers will need to conduct investigations into how and why various problems have occurred in the field or during preparation and distribution of the produce.

These advisory and troubleshooting activities are a vital part of the development of the fresh produce industry in the Eastern Caribbean, but seldom do the extension workers and specialists have any tools other than their own experience and intuition to come up with the answers so badly needed and needed immediately as far as the farmer is concerned.

Recently, the FAO Inter-Island Trade Project (PFL/RLA/001/PFL) obtained 15 portable post-harvest equipment kits for use by trained individuals in each of the eight independent countries in the Eastern Caribbean. The portable kits are intended for use by extension workers and specialists working in the field measure produce temperature, humidity and temperature of air in stores or ambient conditions, sugar concentrations in fruits approaching maturity, as well as monitoring temperatures during storage and distribution.

Below, is a list of such equipment and possible suppliers together with their names, addresses and other contact details. It must be stressed that the particular suppliers listed are not in any way recommended and others exist which may also be appropriate. Whenever considering purchase of any equipment, it is advisable to request quotations from as many suppliers as possible because fluctuating currency exchange rates and varying rates for freight and insurance for delivery will significantly alter the final price. Many suppliers may consider discounts of as much as 10 per cent or more on purchases of ten or more units at a time.

11.2. Equipment and possible suppliers

(i) Hand-held Refractometers

These are durable and very reliable (when used properly) field instruments for measuring sugars or soluble solids in fruits such as melons, citrus, pineapple and others. Some refractometers measure per cent sugars directly, while others measure soluble solids in Brix units which need conversion to per cent sugars.

The 'Atago' type refractometer is self-compensating for temperature differences (but for a higher price of course!) but other units need to refer to temperature compensation tables. In practice, readings taken at ambient in the Eastern Caribbean region will be approximately 0.5 to 0.75 per cent low than actual sugar per cent.

Possible suppliers include:

Bellingham and Stanley Ltd., Longfield Road, North Farm Industrial Estate, Tunbridge Wells, Kent. TN2 3EY. England. Telephone: 892-36444 Telex: 95453 (REFRAC G) Fax: 892-43115

McCormick Fruit Tech., 6111-A Englewood Avenue, Yakima, Washington 98908 USA. Telephone: 966-3999 No telex/fax details!

(ii) Humidity Measurement

Humidity measurement in stores or of ambient air can be made either electronically or by the wet and dry bulb thermometer principle. Static wet and dry bulb thermometers are far too slow in measuring humidity but in the form of a whirling hygrometer or sling psychrometer are a very reliable, cheap and rapid method for humidity measurement. Whirling hygrometers come in several designs and makes and choice should be based on price and durability for field use. Do not forget when ordering, to request spare thermometers (they get broken when misused!) and wicks for the wet bulb.

Possible suppliers include:

McCormick Fruit Tech. (see above for details) ELK International Ltd.,. Eastman Way, Hemel Hempstead, Hertfordshire HP2 7HB England. Telephone: 442-218355 Telex: 825239 (ELELTD G) Fax: 442-52474

There are various types of portable electrical equipment capable of rapid measurement of humidity but these are generally more expensive than the whirling hygrometer and often take longer to equilibrate to ambient conditions which are changing in humidity. Most electronic humidity measurement devices also give air temperature measurement at the flick of a switch, thus giving two pieces of equipment for the price. However, the same instrument cannot be used for measuring produce temperature which is a far more important indicator of produce condition and market or store life.

Possible suppliers include:

ELE International Ltd. (see above for details) McCormick Fruit Tech. (see above for details) Kane-May Ltd., Swallowfield, Welwyn Garden City, Hertfordshire, AL7 1JP England. Telephone: 707-331051 Telex: 25724 (KAMAY G) Fax: 707-331202

(iii) Temperature Measurement

Air temperature measurement can often be reliably measured using an accurate mercury thermometer such as the dry bulb thermometer in a whirling hygrometer, or a static Maximum/Minimum thermometer of the 'Taylor' type which is usually only seen in a Stephenson Screen with other weather recording instruments.

Max/Min thermometers are also very useful in registering the extremes of air temperature experienced in a store and will thus give a good indication of when things go wrong with refrigeration. Many different suppliers exist, including all of those already listed except for Bellingham and Stanley, and Kane and May.

Measurement of produce temperature is actually far more crucial when storing, ripening, or distributing produce and requires insertion of a reinforced glass pulp thermometer or a thermister type metal probe linked to an electronic metering device. For nearly all purposes, the electronic type with a solid chisel-type thermister probe are preferred, and can usually be obtained relatively cheaply. The electronic types usually have a digital display and run off of small batteries. They are very durable and generally very fast and accurate in their response. The advantage of the probe is that produce temperatures, hydrocooling or dip-tank temperatures and even air temperatures can all be measured with one piece of equipment.

Possible suppliers include:

Kane-May Ltd.
ELK International Ltd.
McCormick Fruit Tech. (see above for details)


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