Paneer Yield Collapse in a Small Dairy Unit
A small dairy unit converts 150 L of cow milk containing 4.0% fat and 8.5% SNF into paneer. The milk is pasteurised at 72°C for 15 s, cooled to 75°C, and coagulated with a 2% citric acid solution added slowly until the whey pH is 5.0. The curd is cooked at 80°C for 15 minutes, stirred vigorously, drained in muslin, and pressed for 20 minutes under a 5 kg weight. The batch yields 17 kg of paneer with a crumbly, rubbery texture, a sour taste and 48% moisture. The owner expected 24 kg and complains that 'the milk is poor'. The unit sells paneer at ₹320/kg; milk costs ₹34/L, and the previous batch from the same milk gave 23 kg when the final pH was 5.4 and the curd was pressed for 60 minutes.
1. Calculate the expected yield range and assess whether the 17 kg result is mainly a process loss.
Read the worked answer
For cow milk of this composition, a reasonable paneer yield is about 15–18% of milk weight, or 22.5–27 kg from 150 L. The previous batch at 23 kg (15.3%) confirms that the milk can reach the lower part of that range. The present 17 kg is only 11.3%, a shortfall of 5.5–10 kg against the expected range. At ₹320/kg, the missing paneer is worth ₹1,760–3,200. The milk itself cost 150 × ₹34 = ₹5,100. At 17 kg the sale value is ₹5,440, leaving only ₹340 before labour, energy, coagulant and packing; at 24 kg the value is ₹7,680, leaving ₹2,580. The comparison shows that the loss is not a marginal accounting issue but the difference between a viable and a barely viable batch. Because the same milk previously gave 23 kg, the milk supply is not the main explanation; the change in process conditions must be examined first.
2. Diagnose the likely causes of the low yield and poor texture.
Read the worked answer
The final pH of 5.0 is too low for paneer. At that acidity, casein loses calcium, the curd contracts strongly and becomes crumbly, and soluble proteins are lost in the whey; the sour taste is consistent with over-acidification. Heating to 80°C and holding for 15 minutes, followed by vigorous stirring, shatters the curd into fines that pass through the muslin and are lost with the whey. That explains both the rubbery, crumbly texture and the low solids recovery. The 20-minute press is short for good fusion, but the 48% moisture is not the main cause of low yield; it indicates that the curd has been dehydrated by the high cook temperature, so the loss is solids, not water. The previous batch used pH 5.4 and a 60-minute press and gave 23 kg, which supports pH and curd handling as the controlling factors. Before blaming the milk, check the acid concentration and addition rate, the actual milk pH, the cook temperature and the amount of fines in the whey.
3. Recommend process changes and simple checks the owner should use in the next batch.
Read the worked answer
Standardise and test the milk first, then pasteurise and cool to about 70–75°C. Dilute the citric acid more fully, add it slowly with gentle agitation, and stop at pH 5.3–5.4, checking with a calibrated pH meter rather than by eye. Allow the curd to rest for 5–10 minutes before draining, cut and handle it gently, and avoid vigorous stirring at high temperature. Press for 45–60 minutes under a properly sized weight, then measure the yield and moisture of the finished paneer. Record milk volume, fat, SNF, pH at coagulation, cook temperature, pressing time and yield for every batch so that a change can be traced. Keep the whey to see whether fines are escaping; a cloudy whey means lost solids. Do a simple cost check after each batch: milk cost, yield in kg, sale value and margin per kg. If the next batch still gives below about 20 kg after pH and handling are corrected, then investigate the milk composition and coagulant quality.