Module 4. Pulse processing

Lesson 16

ROASTED, GERMINATED, FERMENTED AND CANNED LEGUME PRODUCTS

16.1  Introduction

Pulses are consumed in its dehusked and split form which is termed as dal. Pulse milling (dal milling) is accomplished in three major steps namely: loosening of husk, dehusking and splitting of pulses. Pulses are generally consumed in the form of Dal. Processing of pulses is important in improving their nutritive value. The processing methods used are soaking, germination, decortications, cooking and fermentation.

16.2 Processing Methods

16.2.1 Soaking

Soaking in water is the first step in most methods of preparing pulses for consumption. Soaking reduces antinutritional factors present in pulses. Soaking reduces the oligosaccharides of the raffinose family, which are responsible for flatulence after pulse consumption. Soaking also reduces the amount of phytic acid in pulses.

16.2.2 Fermentation

The processing of food pulses by fermentation increases their digestibility, palatability, and nutritive value. Soybean is very valuable pulse whose protein approaches the quality of animal protein. However, it cannot be directly used as food because of the anti-nutritional factors present in it. The anti-nutritional factors can be eliminated by fermentation process. The common examples of fermented product are idli and dosa (blend of fermented black gram and rice). This fermentation process improves the availability of essential amino acids.

16.2.3 Germination

Germinated legumes are also occasionally used as traditional legume foods. Sprouting causes partial breakdown of starch and proteins and contributes to the better digestibility. Sprouting also improves flavour of the legume. Sprouted legumes can also be used as a ready-to-use marketable product. Sprouting causes hydrolysis of the oligosaccharides, also responsible for causing flatulence of legumes.

16.2.4 Puffing

Puffed legumes are cheap and popular food for the common man. Puffing and toasting of pulses is practiced all over the country. The flavour and light texture of the product makes it popular among all age groups. These products are traditionally used as snacks. Puffing is effected by manual or mechanical roasting of conditioned legumes in hot sand. The increase in size is 1.5 to 2 times of its original size.  Bengal gram and peas are best suitable for puffing. The puffing expansion during roasting is maximum in Bengal gram which is most popular for puffing.

The grains are first soaked in water for short duration (1-3 minutes), mixed with sand heated to 250ºC and toasted for 15-25 seconds with agitation. After sieving off the sand, the grains are dehusked between a hot plate and a fast rotating rough roller. The yield of puffed product is about 65-70% by weight.

16.3 Legume Products

16.3.1 Canned legume products

Many pulses are required to be cooked soft for consumption. The cooking time needed for softening is long (15-45 min.). Instant or quick cooking pulses is necessary for modern urban consumers. Retort processed pulses in cans are now available in the super markets.

16.3.2 Besan manufacture

Besan is made from chana dal (Bengal gram). Its production involves three major steps namely size reduction, sieving and packaging. Besan is made in rural areas and at home scale level in burr mills (atta chakki). Capacities of such machines vary in between 50-100 kg per hour.

Some manufactures employ Pulverizers (hammer mill) along with reel sieves (recovery of besan is 98%). The reel sieve is generally fitted with a fine nylon cloth (112 mesh). It has a blower rotating on its axis at 350 rpm. This helps in blowing out the fine powder out of the reel which is collected at one end by auger. The coarse powder discharged at other end is fed back to hammer mill by a bucket elevator.

16.3.3 Papad manufacture

Papad is a thin round rolled sheet of dried papad flour. Papad flour is made by combining few pulses flours like urad, moong etc. In some papad flours, gram pulse is also added. Rolling papad is generally a manual operation done by women folks. The papad flour along with spices like black pepper, jeera, baking soda and salt is tightly kneaded with water and then rolled.

CFTRI has developed a papad mill where kneaded papad flour is pressed in round thin sheet by keeping the dough in between two polyethylene sheets and placing it in between two parallel discs. One disc is pressed against other with the help of foot through a lever. The capacity this machine is about 500 papad an hour.