Module 9. Paneer

Lesson 22

RECENT DEVELOPMENTS IN PANEER MANUFACTURING, YIELD, COMPOSITION, FACTORS AFFECTING QUALITY, PACKAGING AND SHELF LIFE

22.1  Use of Ultra Filtration in Paneer Manufacturing

Ultrafiltration(UF) in paneer making offers the advantages like adaptation to mechanization, uniform quality, improved shelflife, increased yield and nutritionally superior product. In this process milk after standardization and heating is passed through UF membrane where lactose, water and some minerals are removed as permeate.

The concentrated mass which has about 40% total solids is cold acidified to get the desired pH. Upto this point the product is flowable and can be easily dispersed into containers with automatic dispersing machines. The filled containers can then be subjected to texturization by passing through microwave tunnels. The resulting product has typical characteristics of normal paneer. The yields increase by about 25% which is due to the retention of good quality whey proteins and slight increase in moisture content (moisture about 70%) yield is about 25%.

22.2  In-package Long Life Paneer Like Product

A fully mechanized process was developed which yields a long shelf life paneer like product. In this process, standardized buffalo milk is concentrated partly by vacuum concentration and partly by UF to a T.S. content of 30%. Acidified using GDL – Glucono Delta Lactone. After packaging in metallized polyester pouches, the product is formed by texturizing process at 115°C for 5 min which permits concomitant sterilization. The yield of paneer is more due to retention of whey solids and the shelf life is 110, 80 & 47 days at 25, 35 and 45°C respectively.

22.3  Continuous Manufacture of Paneer

A continuous paneer-making system was developed at NDRI, Karnal by Agarwala (Fig. 22.1). In this system, the unit operations involved in paneer making have been mechanized. The continuous paneer making machine is designed to manufacture 80 kg paneer per hour by employing twin-flanged apron conveyor cum filtering system for obtaining the desired moisture content and texture attributes.

Fig. 22.1  Schematic diagram of continuous paneer manufacturing unit

1. Feed tank, 2. On-line filter, 3. Feed pump, 4. Plate heat exchanger, 4a. Regeneration system, 4b. Heating system, 5. Holding tube for heated milk, 6. Hot water, 7. Acidulant tank, 8. Acidulant pump, 9. Flow control, 10. Flow diversion valve, 11. Rotameters, 12. Temperature indicators (T1 and T2), 13. Transverse jet mixer-reactor, 14. From TJM-R, 15. Primary whey drainage. 16. Entrance of curd pressing zone, 17. Upper conveyor, 18. Lower apron conveyor, 19. Scrapper, 20. Paneer outlet, 21. Wet scrubber, 22. Fixed conveyor shaft, 23. Adjustable conveyor shaft, 24.Whey outlet, 25. Adjustable support, 26. Spray nozzles (Source: Agarwala, 2006).

The milk heating unit consists of a plate heat exchanger with provision of heat regeneration, heating of milk from 25^oC to 90±2^oC holding for two minutes and cooling to 70±2^oC. Other accessories in this unit are balance tank, pump, flow meter, temperature indicator and auto thermal control unit, etc.         

The continuous dewatering and matting unit consists of twin apron conveyer to carry out primary and secondary filtration in the same machine. The lower conveyor is flanged type while the upper one is unflanged type. The flanged unit has perforations for drainage. The additional fine filter of appropriate size is placed over the conveyor to prevent the solids loss. The linear speed of the conveyor is designed to provide optimum residence time required for adequate dewatering. Flexibility in the motion is incorporated through a variable speed drive, giving 5-8 min of residence time. Increasing the width of conveyor can increase capacity of this unit. 

22.4  Frozen Paneer

This is most commonly adopted method in dairy industry. Paneer slabs are cut into small cubes of about 1cm³ or 1.5 cm³ and then cubes are kept in deep freezer or pass through freezing tunnel to freeze them to-18°C or below. These frozen cubes are packed in a metalized laminates and vacuum packed.  Advantages of this method are;

· Less time consumption while thawing

· After thawing one can directly use for preparation of various dishes

· Quickly freeze to -18°C or below

22.5 Yield

The yield of paneer is dependent on the fat and solid not fat(SNF) content of raw milk, as well as the moisture, fat and protein retained in the paneer. Co precipitation of casein and whey proteins is the simplest way of recovering whey proteins and thus increasing the yield of paneer. Heat treatment of milk to 90°C is necessary to achieve good yield. Generally a yield of 20-22 kg is obtained from buffalo milk and 16-18 kg from cow milk.

22.6 Factors Affecting Quality and Yield of Paneer

22.6.1 Type of milk

Paneer prepared from buffalo milk possess desirable frying properties, body and texture as compared to cow milk. The cow milk paneer is soft, weak and fragile and during cooking it tends to disintegrate. However, cow milk and buffalo milk mixed in equal quantity yields better product than cow milk. Paneer made from skim milk has chewy and rubbery texture and hard body.

22.6.2 Quality of milk

Milk must be fresh and free from off falvour. Growth of psycrotrophic organisms should be minimized to restrict the off-flavour development. Acidic milk having a titratable acidity of more than 0.20% lactic acid yields a product of inferior quality. Milk with COB positive and low acidity (sweet curdling) is not suitable for paneer making. Paneer made from such milk has weak body and texture, more moisture, acidic smell and not safe for human consumption.

22.6.3 Type, strength and temperature of coagulant

Product yield and moisture retention are directly influenced by the type and concentration of the acid and the mode of delivery and blending into the hot milk. Citric acid is generally used as a coagulant. Lemon or lime juice or vinegar imparts a typical flavour to the product. 1% solution of citric acid yields good quality of paneer. Sufficient acid is added gently but quickly blended with the milk (within one min) to reach optimum pH of coagulation. Normally 1.8 to 2.0 kg citric acid is required for coagulating 1000lit of milk. High acid concentration imparts acidic flavour, hardness and causes greater solids loss. Whey cultured with Lactobacillus acidophilus at a level of 2% and incubated overnight at 37°C can be used as a substitute for citric acid. However acidic whey must be heat treated to destroy these lactic organisms before use to prevent loss of shelf life of paneer.  Coagulation temperature influences the moisture content of paneer. It is reported that an increase in temperature from 60°C to 86°C decreases the moisture content from 59 to 49%. However, optimum coagulation temperature for best organoleptic and frying quality product is 76°C.

22.6.4 Heat treatment of milk

This is one of the technological requirements of the process which affects the sensory and microbiological quality of paneer. The objective of heating milk is to prepare it for rapid iso-electric precipitation, control the moisture content, develop typical body and texture, create conditions conducive to the destruction of pathogenic and other microflora present in milk and ensure safety as well as keeping quality of the final product. The milk is heated to 90°C without holding or 82°C for 5min in order to maximize the total solids recovery. Whey proteins especially β-lactoglobulin and α-lactalbumin form a complex with Қ-casein and retained with the curd thus increasing the yield of the product. The high heat treatment imparts desirable cooked flavour by controlled liberation of sulphydryl compounds.

22.6.5 Coagulation temperature

It influences the moisture content of paneer. An increase in temperature from 60°C to 86°C decreases the moisture in paneer from 59 to 49%. At 70°C, paneer made from buffalo milk has the best organoleptic and frying quality in terms of shape retention, softness and integrity.

22.6.6 pH of coagulation

The optimum pH of coagulation of milk at 70°C is 5.30-5.35 for better product quality and maximum recovery of solids when made from buffalo milk. The moisture retention in paneer decreases with the reduction in pH and consequently the yield also decreases. At pH more than 5.35 the paneer is very soft with fragile and crumbly body. Optimum pH for paneer preparation from cow milk is 5.2.

22.7 Composition

Following table depicts the proximal chemical composition of paneer.

Table 22.1 Composition of paneer

Parameter	Percentage
Fat	23.41(50.84 on dry matter basis)
Protein	18.23
Lactose	2.40
Ash	1.90
Total solids	46.04

22.8 Packaging and shelf life

Polyethylene pouches, cryovac films, co-extruded laminates and retort pouches, are being used for paneer packing. Vacuum packaging of paneer in laminated pouches increases the shelf life to about 30 days at 6°C. Paneer packaged in laminate (EVA/EVA/PVDC/EVA) under vacuum and heat treated at 90°C for one minute increases the shelf life upto 90 days under refrigeration. Paneer packed in tins along with water/ brine and sterilized in an autoclave at 15 PSI for 15min lasts for 4 months. The product can be stored under frozen conditions (below ‑18°C) for more than one year without any deterioration in its quality and used after careful thowing. Paneer dipped in 5% brine solution lasts for about 22 days at 8-10°C. The salting at the time of dipping into chilled water can be used in extending the shelf life of paneer. Dipping in benzoic acid (1200 ppm) increases the shelf life of paneer to 40 days at refrigerated temperature and 20 days at 37°C. By adding sorbic acid to milk (0.15%) and subsequent wrapping of paneer in sorbic acid coated waxed paper, the shelf life of paneer can be increased to 36 days at room temperature.

Reference

Agarwala, S.P. 2006, Equipment for paneer making, Lecture compendium on developments in traditional dairy products, a short course organized by CAS from Dec. 10-30, 2006: pp-132-137.