The cultivated groundnut is defined as one of four types: i.) runner: runner have become the dominant type, because of their attractive size range which makes them useful for a variety of products; ii.) Virginia: Virginias have the largest kernels and account for most of the groundnuts roasted and eaten as in-shell. When shelled, the larger kernels are sold as salted-groundnuts. They are also used in confectionery products; iii.) Spanish: Spanish type groundnuts have small kernels covered with a reddish-brown skin. They used predominately in groundnut candy, with significant quantities used for salted nuts and groundnut butter. They have a higher oil contents than others types iv.) Valencia: Valencia's usually have three or more small kernels to a pod. They are very sweet groundnut and are usually roasted and sold in the shell. They are excellent for fresh use as boiled groundnuts.

After drying, groundnut pods are graded at a prescribed moisture level in the kernels such as 9 percent. Undersized pods, chaff, inert matter, if any, is separated. The factors such as foreign material over 4 percent, moisture over 7 percent, damage over 1 percent, loose shelled kernel content, and split percent over 4 percent determines the value of the produce in the national and international markets. Seed size is another important characteristic that also determines both quality and value. The 100-seed weight may differ among genotypes from <30 g to >150 g. Size also varies within a genotype, and cultivars with more uniform seed size are desired for improved processing efficiency and marketing of groundnut products.

 Figure 19. Groundnut grader line diagram (Source: NDDB, Manual on Groundnut).

India produces two sizes of groundnut kernel, medium and small. The medium-size kernels, known as "Bombay Bolds", generally count 50/55 kernels per ounce. They can also be graded to 40/50 kernels per ounce, though availability at this size is not unlimited. The small-size kernel are called the "Java" type, is equivalent to the US "Spanish" or the South African "Red Natal". The generally traded grade of Java is 70/80 kernels per ounce. In internal trade the quality of pods and kernels is judged by a visual examination except in contract sale when the proportion of damage kernels, nooks, broken and splits, percentage of foreign matter, and moisture content is determined. The ISI has prescribed certain grades for groundnuts (kernels for oil milling and handpicked selections) produced and marketed in the country. These standards are based on the trade practices followed in the country in respect of the type and grades. The specifications are given in Table 9. A line diagram of groundnut grader is shown in Figure 19.

Table 9. ISI specification for groundnut kernels for oil milling.

For preparing export grade edible groundnut, "Hand Picking and selection" (HPS) through hired labour is still in practice. Although, in the Indian context, human endeavour is worthy of appreciation and encouragement, the need to install mechanical graders cannot be over emphasized. Use of machine for grading groundnuts will not only be faster and more reliable but hygienic also. Optical sorting machine grading is not used at present, but colour sorters are now in use in some developing countries to remove aflatoxin-infested kernels. The ISI (Indian Standard Institute) specifications for the HPS are given in the following Table 10.

Table 10. ISI specifications for groundnut kernels- handpicked selection (HPS).

Note: The groundnut kernels shall also be free from non-edible oils such as mahua, castor, neem and argemone.

2.7.2 Packaging

Pods after grading to the requisite normal size are packed in gunny bags. Seed are seldom shelled and packed because in the kernel (seed) form they lose viability quickly than in-shell (pod) form. Therefore, seed is mainly sold in the form of pods and a small pack of thiram or captan is also kept in the gunny bag with the instruction to treat the seed (kernels) at the time of sowing. Packing for the milling or seed purpose in polyethylene bags is generally recommended, as it helps in maintaining the quality during storage. Similarly in several developing countries the roasted kernels are sold loose in the market, packaging of the confectionery groundnut in polyethylene bags may add to the value and quality of the product in the local markets. Other value-added product should also be sold with proper packaging to maintain the moisture content and the crunchy and crispy nature of groundnuts (Figure 20).

 Figure 20. Confectionery groundnut available in polyethylene packages.

After filtration groundnut oil is packed in big drums or tanks, and in tins of 15 kg capacity. A part of the population in the developing countries, living below the poverty line, purchase unbottled or unpackaged groundnut oil for their consumption from the market daily. This practice boosts the risks of adulteration. Recently the Government of Gujarat has decided to make packaging compulsory for groundnut oil sold in the market. Even quantities as small as 50g of groundnut oil will require packaging before sale. This will have a major impact on the state's edible oil market, leading to a 10 to 15 percent price increase in this politically sensitive commodity. Similar regulations are desirable from other governments in the developing world.