Chilli used as a spice has agricultural and marketing specifications and also food standards in national regulations since chilli is a food, a food supplement or a food adjunct. Concerns on quality and safety emerge on account of occasional aberrations of adulteration, contamination and pollution. Relatively stable pollutants of air, water and soil get to this plant product engendered by all these three. Needless to say, adulteration is intentional and contamination incidental. The latter exceeding the limits of good agricultural and manufacturing practices changes to adulteration even if not intentional. This chapter deals with adulteration in the whole, in the form of powder and paste of chilli. The details include microscopic detection of adulterants, estimation of carotenoids and non-volatile ether extract of extracted chilli and that influenced by addition of edible oils. Contaminants specially in respect to irradiation and added colors are included. Pollutants include trace metals, pesticides, mycotoxins and microbes. Insect-infested and insect-damaged chilli may not be rare in tropical regions.
Chilli is not an esoteric spice and is not very costly either. Even then, it attracts its own moderate share of adulteration, which by all means requires to be taken into consideration. Both for cheapness and a very pronounced sensory bite it is utilised extensively by common and poor people specially in the developing countries. High incidence of pungency, as revealed by high Scoville units (factor of manifold dilution, which still retains pungency), is responsible for tickling the taste buds of pungency making even a bland or insipid food gastronomically acceptable. This is the first choice from the spices among poor people who consume mostly chilli in absence of multiple dishes or varieties and hence its turnover is considerable. It is the spice of the people. Even though adulteration, contamination or pollution in chilli is not extensive, it is duly surveilled for quality control during harvesting and post-harvest processing, commercial transaction and trade, and activities towards food and flavor regulations. The powder or the paste of chilli is more vulnerable to adulteration as foreign substances can go into it visually undetected.
Adulteration in chilli
The following points of adulteration may be considered:
1 Extraneous matter including calyx pieces, loose tops, dirt, lumps of earth, stones and mould growth, etc. If the mould or the sprouted spores are identified as those producing toxins, e.g. Aspergilli or Penicillia, the apprehended mycotoxins should be looked for.
2 Extraneous coloring matter (), coating of mineral oils () or other facing and coating liquids or powders.
3 Insect-damaged foods and related matters.
4 Harmful substances.
The items are analysed as usual. While in whole chilli insect damage is estimated by refraction, that in powder or paste is estimated by colorimetry of uric acid () and by chromatography techniques ().
Powdered (or paste) chilli
1 Excessive moisture, dirt, dust, mould growth, insect infestation, fermentation, extraneous matter, and added coloring and flavoring agents are the main adulterants.
2 It is claimed that a small amount of edible oil is used for post-harvest processing of whole chilli and powdering or pasting chilli. Hence, Indian standard specification allows a maximum of 2% of such oils in chilli powder with the following labelling declaration “Chillies in this package contain an admixture of not more than 2% of … (name of the edible oil)” (Food Regulations, 1955).
3 Microscopic detection of adulterants: Microscopic structure of chilli powder or paste has been worked out (). Thus, aleurone, chloroplasts, cuticle, cuticle grooves, endocarp, endosperm, exocarp, giant cells, hairs, hypodermis, mesocarp, oil drops, phloem, fibre, seed coat, spiral vessels, stone cells, vascular bundles, xylem fibres, etc. have been recognised and documented. It is possible for any foreign matter to be recognised by the presence of uncharacteristic structures or by detection of well-known foreign microscopic structures like different starches. Chilli powder is not known to have starch granules, though acid hydrolysed and diastase () treated cell contents can provide reducing equivalents not of glucose but of pentoses from pentosans and hemi-celluloses. Powdered calyces and pedicels if present in excess in chilli powder or paste will constitute adulteration.
4 Chilli is cheap and even though at present there is no major market for capsaicin, the pungent principle of chilli, or its derivatives, it will soon be in great demand due to its preservative, antioxidant and medicinal properties. There is a possibility that chilli (whole or powdered) can be partially extracted of capsaicin. Such samples can be deemed adulterated as anything abstracted or added without labelling constitutes adulteration. This deficiency can be detected by estimating the pungency in Scoville units (International Standards Organisation, 1977) and its deficiency from usual and undisputed concentration of capsaicin or from the lowest concentration as permitted in the standard specification. It is possible that capsaicin is taken as a parameter along with others for grading chilli. The deficiency will decrease the non-volatile ether extract of chilli, which is an important analytical parameter of authenticity of a sample of chilli.
Detection and estimation of carotenoids can also be carried out in normal and extracted chilli (). If the normal value is established by analysing a large number of any particular variety, then the deficiency in the extracted samples can be detected.
5 It is possible that the non-volatile ether extract of chilli can be fraudulentally boosted by oils. This can be ascertained by detecting if mineral oil is added () or by estimating iodine value of lipids extracted from chilli powder. Chilli seed oil has an iodine value of 126, which will be increased or decreased according to the extraneous oil added.
The possible contaminants are agricultural and biological residues, fungi, rodent hair and excreta, radioactive and radioiytic products (as chilli powder specially the old specimens can be irradiated by ionising radiations if national legislation permits), insect ova and pupa, etc.
All these contaminants will call for specific analytical exercises. While refraction will answer for visible contaminants physically present and microscopy for ova and pupa, the invisible rodent excreta of urea is detected by TLC ().
If chilli samples are to be preserved or protected by exposure to ionising radiation, it has to be done in conformity with the statutory provision in force (Food Regulations, 1955). The dosage for chilli is 6, 14 and 10 kGy as minimum, maximum and overall average, respectively.
Colors are not added or allowed to be added in whole chilli or its powder and paste. If colors are added, the samples can be condemned as misbranded or as adulterated. The relevant analyses () rely on color change in ether and alcoholic extracts with 3:1 or 4: 1 HC1 and on reversed-phase chromatography of alcohol (90%) extract of chilli wherein the natural and synthetic colors are resolved. While the natural colors vanish in a day or two in the chromatogram, the added synthetics are stable. Banerjee et al. () isolated fat-soluble colors by extraction with hexane, partition by dimethyl formamide and water and chromatography on activated alumina. The isolated colors were separated and identified by thin layer chromatography and differentiated from natural colors.
The main environmental pollutants in whole chilli are toxic trace metals from agronomic sources particularly agricultural, chemical and processing operations. As per regulation (Food Regulations, 1955) the maximum allowable concentration in ppm of some metal pollutants in chilli is given below:
|Metal||Maximum allowable concentration (ppm)|
Pesticide residue can also be a class of pollutants as in other agricultural commodities, and at times it could be under surveillance as provided in regulations. When the history of use and names of pesticides in a sample of chilli are not known, the generalised methods for the particular class of pesticides can be used followed by specific tests for the individual pesticides (). However, the presence or qualitative detection to be determined within a short time if standardised well will be welcome; if positive it can be followed for pinpointing and quantitation of the pesticide present. Suitable insects can be utilised for the screening for only the presence of pesticides in general (). These authors showed a possibility of laboratory rearing of an insect for preliminary detection of the presence of any pesticide.
Mycotoxins particularly aflatoxins are sometimes looked for. Our laboratory had continuous monitoring of market samples of food for aflatoxin pollution. As no positive cases on chillies came to light, no firm conclusions could be made in this regard. The usual limit of aflatoxins in chilli is 0.03 ppm.
This laboratory looked for microbial spores in chilli powder among others but no significant case with potential of microbial spoilage or toxicosis was however reported (). Antimicrobial effect of chilli, though mild, could help inhibit some microflora of the foods, but, on the other hand, spices are known to (it is possible that chilli too) stimulate the growth of lactic acid bacteria. This is reportedly a result of their manganese content.
If the microbial content is even moderate and if the chilli is not sterilised the food may be contaminated and to the extent spoilage will occur. Needless to say the number of thermophilic flat sour spores and thermophilic types not producing hydrogen sulphide should be low if the spice is to be used in canned products like canned curry and meat. Such type of organisms do not have the same importance in non-canned products.
Chillies showing very high microbial counts are likely to be of low sanitary quality and indicative of none-too-well hygienic practices in the production and handling. These counts can be used as a guide for judging contamination and designing uses.