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Even though India has been in the forefront for export of spices for several centuries, it was not until the mid-80s that the word 'quality' assumed importance. The imposition of quality standards by importing countries resulted in efforts for quality assurance. The steps were taken by the Spices Board to develop and inculcate good post-harvest management right from the stage of harvesting—particularly in seed spices.
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The right stage of harvest decides the quality, viz., size, colour, fibre content, volatile oil, chewing quality (fennel), splitting (coriander), etc. Clean drying. proper winnowing to remove dirt, chaff, plant parts, birds' droppings, rat excreta, hair, etc., followed by storage in hygienic and well-ventilated godowns ensures a good product. At the international level there is a stringent quality standard which has to be met by exporting countries. The specifications of American Spices Trade Association (ASTA) and the International Organisation for Standardisation (ISD) guidelines, with mutually agreed terms are followed.
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Japan and many other countries use the ASTA specifications; India, Malaysia, Spain, Indonesia, Sri Lanka and Hungary have their own quality standards for exporting spices. ASTA specifications are for unprocessed spices imported into the USA, and they regulate the cleanliness of these spices. ASTA specifications place limits on extraneous matter (insects, insect excrement, stones, stems, sticks, moulds, etc.) and set standards in sampling and testing procedures. Imported spices not meeting these specifications are reconditioned at the port of entry, while local spices need to be reconditioned (using fumigants) before they are processed for use in a product.
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The US Federal Specifications establish quality standards for whole and ground spices. Specifications include total ash, acid-insoluble ash, volatile oil, moisture, colour and granulation, and these are standardized for the major spices. These specifications have maxima or minima values that differ considerably between importing countries. Standards for defective spice (stalks, stems or other contaminants) are also established. The ISO has specifications for most spices, such as extraneous matter, moisture content, total ash, acid-insoluble ash and other chemical characteristics. Based on the ISO, Britain and Canada have established their own standards. Spices that are irradiated, reheated with ethylene oxide or contaminated with aflatoxin are prohibited under the Japanese Sanitation Law.
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In India, quality standards are established for unprocessed and processed spices that particularly regulate moisture content, volatile oil, total ash, acid-insoluble ash, starch and extraneous matter. Grades are also established with specifications. Many spices, such as turmeric, black pepper, ginger and chilli peppers, have individual grade specifications that differentiate them from similar spices. Even curry powders are graded based on the amount of spices and salt they contain. Similar specifications are established for spices in many other countries.
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Grinding and sterilizing procedures decrease the volatile oils in spices. Excessive heat volatilizes and dissipates the essential oils in ground spices, and high humidity tends to cake them. Exposure to light, humidity variations, air and certain metals can discolor many spices such as paprika, turmeric or the green leafy spices. Dry, ground chilli peppers turn from a natural green or red colour to an olive or dirty reddish-brown colour when exposed to light. Flavour and aroma losses, as well as insect and rodent infestation, occur when spices or spice extracts are stored in tightly closed containers in cool, dark, dry conditions below 4.4°C and 60% humidity.
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Some spices need storage at low temperatures of about 2-5°C to prevent mould infestation (capsicum peppers), colour deterioration (paprika) and to avoid rancidity (in high fixed oil seeds, such as sesame seeds). Colder temperatures also help preserve the volatile oil flavour and aroma, freshness and sanitary quality; refrigeration slows microbial growth. Whole spices tend to have better shelf life than ground spices. Ground spices for minimally processed foods such as salad dressings, condiments or 'sprinkle on' seasonings should be well cleaned and sterilised.
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High levels of moisture in ground or whole spices indicate mould and microbial growth. During storage, insects breed on spices in varying degrees, depending upon storage conditions, where they are harvested, transportation contamination and the extent of cleaning. Filth levels include foreign materials such as insect fragments (moths, mites, beetles), small stones, metal fragments and glass pieces. Insects and mould growth can change the colour and, to some extent, the flavour of the spice.
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Microbiological requirements for 'clean' spices include counts for total bacteria, yeast, mould, coliforms and food pathogens such as Eschersia coil and Salmonella. High microbial counts are caused by contamination during growing and post-harvest handling. Spore- forming bacteria, such as the Bacillus species or Aerobacter aerogenes found in the soil can be transferred to the spice during the drying process, particularly to 'under the ground' spices such as turmeric, ginger, galangal or garlic. The type and amount of moulds and bacteria on a spice depends upon the type of spice and the conditions under which it is harvested and dried. Staphylococcus and Streptococcus species of bacteria predominate, but pathogenic bacteria tend not to exist on spices.
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Spices that show strong antimicrobial properties tend to have low counts of microbes. Moulds, such as Aspergillus, that produce the toxin Aflatoxin and Penicillium, are found on certain species including red pepper, fenugreek and ginger, so there are specification limits for these toxins. Moulds tend to multiply during the drying process and storage. The control of insects and microbes is important in receiving quality spices. Spices need to be free of microbes so as to reduce the initial bacteria or mould content in processed foods. Spice extractives and sterilised spices tend to meet these objectives. Organic foods are becoming more popular, and for food to be labelled as organic, irradiation is not permitted. Spices that are not sterilised can be potent sources for microbial contamination and growth.
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