Why Colour-Sorting Matters in Loba — and What “Uniformity” Really Costs

When a retail packer or exporter asks for “uniform” loba (alsande / cowpea / black-eyed pea), they are really specifying a discard rate. Colour sorting removes off-colour, stained, mottled, and defective seeds from the accepted lot. What leaves the yard as sorted loba is what remains after that removal. The cost of uniformity is, therefore, largely a function of how much of the incoming lot must be discarded to meet spec — and in our experience at KVM & Co., Mysore, buyers routinely underestimate this number.

What buyers actually mean by “uniform”

“Uniform” is not a single standard. In practice, when processors and packers use the word, they are usually bundling together four separate requirements:

Colour consistency

Predominantly one colour class — white / cream for white loba (karamani), or red-eye for red-eyed varieties — with off-colour seeds typically below 2–3% by count.

Broken percentage

Seeds split or missing more than a quarter of their body. Below 2% for premium lots. BIS IS 1154 (cowpea and related pulses) uses this as a principal quality parameter.

Foreign matter

Stones, soil, weed seeds, husk. Below 1% for retail or export. AGMARK Grade 1 sets the same ceiling; Agmarknet publishes the full schedule.

Weeviled seeds

Seeds with pulse beetle exit holes. Below 1% for domestic retail; export markets frequently require zero tolerance.

A lot can pass on colour and still carry 4% weeviled seeds. Uniformity is the intersection of all four — and each one costs you something.

The uniformity trade-off: what each grade discards

The table below reflects typical outcomes we observe at the yard for mixed-colour loba arrivals. Actual discard varies with crop year and source quality, but these bands are representative.

Grade	Sorting method	Typical discard	Colour pass rate	Broken & FM	Relative price vs. unsorted
Standard (minimal sort)	Destoning + winnowing only	~5%	Not guaranteed	<4% broken; <2% FM	Base
Premium colour-sorted	Hand-grading + optical sensor pass	10–15%	>97% on-colour	<2% broken; <1% FM	+₹300–500 / quintal
Export-grade ultra-sorted	Optical sort + size screen + manual top-up	20–25%	>99% on-colour	<1% broken; <0.5% FM; zero weevil	+₹700–1,200 / quintal

The discard re-enters trade as feed-grade loba at a lower price. But the lot you dispatched cannot recover that weight — that is the true cost of the spec you agreed to.

“The part you don’t see leaving the yard is often the most expensive part of a uniform lot.”

How colour sorting works at KVM

At KVM & Co., Mysore, we offer colour-based sorting as a value-added service on loba lots at APMC Yard, Bandipalya. Sorting runs in two stages:

1. Optical sensor sort. Seeds pass through a channel sorter; sensors flag off-colour seeds and ejectors remove them in real time. One pass typically reaches the premium colour-sorted band.
2. Manual top-up. For tight-spec export or retail-pack orders, hand-graders check the sorted output and remove any seeds the optical pass missed — including broken and weeviled seeds sensors are not calibrated to catch. We apply this step only where the spec genuinely requires it.

Hand-grading alone works for smaller lots with low natural colour variation. For mixed-origin arrivals or late-season loba, the optical pass is faster and more consistent.

When paying for colour sorting is worth it

• Retail-packed pulses. The consumer sees through the bag; off-colour seeds drive returns. For FMCG packers, the sorting premium is absorbed easily by the retail margin.
• Export shipments. Gulf, East Africa, and South-East Asian markets carry strict appearance norms. Import rejection on colour grounds costs far more than sorting does here.
• Food-service catering. Hotels and large caterers buying loba for whole-seed dishes treat colour and size consistency as an operational need, not an aesthetic one.

When it is not worth paying for

• Industrial grinding. Milled into besan, flour, or extrudate, whole-seed colour is irrelevant. You are paying a sorting premium and discarding it the moment the lot enters the grinder.
• Large institutional buyers cooking at scale. Pressure-cooked or mashed loba in canteens has no appearance requirement at the seed level. Broken percentage affects cook-time uniformity; colour does not.
• When the incoming lot is already clean. Single-origin, same-season loba often arrives at 94–96% natural colour consistency. One light optical pass reaches spec at 6–8% discard. Full sorting charges on a visually clean lot are worth questioning.