Some compelling cases for food processing: Part III, Dried Milks

Some compelling cases for food processing: Part III, Dried Milks

A case for any processing becomes ‘compelling’ when its advantages far outweigh its disadvantages. In fact, processing of all kinds has expanded simply by picking such cases of large value-addition, enhancing it further and mitigating the negatives. Improving the standard of living of millions of farmers spread all over India thru increased milk production by them and availability of a variety of nutritious products to consumers, is one such compelling general case. In this arena, concentrating milk, partly to condensed milk and fully to milk powder, is a specific case whose detailing is interesting and useful.

Unsweetened condensed milk as ‘partially concentrated milk’: Fluid milk is concentrated to a dense, viscous condensed milk by evaporation of a large part of its water. This happens progressively and continuously under vacuum by heating milk efficiently on a large scale in a plant. This happens faster and at lower temperatures than at home where it is done in an open vessel, in a batch, releasing water vapour to atmosphere. Home process uses more fuel for comparable evaporation in a plant and causes more colour darkening and nutrition loss.

In a plant, such condensed milk is the input to production of spray dried milk powder and hence, barring minor adjustments of water-content, a ‘side stream’, tapped off from the pipe going for spray drying, delivers condensed milk as product. It reconstitutes or dilutes better than milk powder and is popular in the West. (In India, sweetened fluid milk is concentrated to the widely available and popular ‘sweetened condensed milk’.) Obviously, ‘fluid milk to condensed milk to milk powder’ represents increasing concentration, value-addition and cost, and shrinking volume.

India’s sweetened condensed milk can be used in many innovative ways at home (in combination with milk and milk powder) as described later. Here are a few ways in which we Trivedi’s have used  it:

(i) As a topping/dressing for fruit platters. (ii) As a spread for toasted and buttered bread slices with or without chopped berries and pineapple. Sweet condensed milk, mixed with finely chopped strawberries / pineapple / mango between two bread slices and our proprietory multipurpose powder makes a great grilled sandwich. (iii) In eggless, soda-less cake formulations in combination with pulped banana or mango where its viscosity helps incorporate air and gives relatively dense but delicious, and most importantly, healthier cakes. (Remember the importance of avoiding soda?) (iv) In ice-cream and kulfi premixes in a judicious mixture with fluid milk. (v) For making quick rabadi for ‘shahi tukda’.

Milk powder as ‘fully concentrated’ spray-dried milk: Large volumes of milk – an essential, watery, nutritious and perishable commodity – shrink to small volumes of shelf-stable milk powder on full drying.

(Sterile milk in tetrapacks has unrefrigerated shelf-life of months which makes it a ‘kirana’ product. It is an attractive option for whitening tea and coffee in absence of daily milk. Its negatives: 1. Higher cost than daily milk – comparable with equivalent milk powder. 2. It needs to be used fast, (though not as fast as daily milk) after opening the carton and the first ‘emergency use’,  till it is exhausted in a few days. 3. It is available in skimmed or ‘low fat’ version and hence may not be found rich enough for direct drinking and sweet making.)

Since a milk flood is already growing in India, milk powder, along with a few other products, is expected to force itself on domestic and export market requiring innovative use-cases. Thus, the implications of increased production of such milk products and their uses in further processing, are important. One such application of milk powder, deliberately of the home variety, is presented here.

A  DETAILED LOOK AT MILK POWDER, ITS NATURE AND ITS USES

  1. Prelude: All the logic behind making milk powder notwithstanding, reversal of such drying i.e. reconstitution of milk from the powder is always unsatisfactory, at least to the Indian palate. The persistent popularity of the powder stems, not from its use as a milk-replacer, but the fact that most Indian style sweets do require drying of milk to various extents. Such sweets are never powder-dry and hence, combining the powder with water or milk or condensed milk to create various versions of ‘rabadi’ or khoya/mawa sweets is an exciting prospect which deserves detailed analysis in terms of the implications. (When using sweetened condensed milk available in India, don’t forget to account for the sugar in it.)

Industrial milk powder can give sweets with whiter tones – an Indian preference – than home-made khoya or mawa. The latter has a distinct brownish tone and  slight ‘burnt’ flavor that can interfere with colouring and flavouring. This feature of powder-made sweets allows them to be coloured and flavoured extensively; the attractive array of sweets at large halwai shops is the proof. We will talk about totally safe and even nutritious colouring and flavouring of home-made sweets some day.

2. Making of milk powder: We will look at this process in detail later but it essentially entails removal of remaining water from hot, unsweetened condensed milk which is fine-sprayed in a  tower with an upward air current. And hence the name: spray-dried milk powder. All milk powder meant for the FMCG market is ‘instantized’ by an elegant manipulation in the spray drier itself which makes it easily dispersible in water. Do share your experiences on how ‘instant’ you find your milk powder; we will respond by explaining your experience.

  1. Understanding the nature of milk powder: Milk is essentially a mixture of water, milk-fat and non-fat solids. Hence, milk powder is simply a mixture of milk-fat and solids and, like most natural things forcefully separated from water, it tends to absorb water from the atmosphere to form lumps in an apparent attempt to go back to being milk! Such lumping or ‘caking’ becomes pronounced above about 5% moisture and hence moisture-content of milk powder is usually restricted to below 4 % and isolated from atmospheric moisture. Hence, it can be treated as practically composed of only milk fat and non-fat solids.

If made from fat-less (or ‘skimmed’) milk, it is called Skimmed Milk Powder (SMP) which is essentially non-fat milk solids. A formulation close to milk powder is ‘Dairy Whitener’ which is nothing but a free-flowing version with some additives so that it ‘whitens’ hot and cold, tea and coffee by direct addition. This happens millions of times daily in the West and on airplanes.

As an alternative, fluid milk in tiny circular cartons as whitening ‘dose’ for each cup, is not uncommon. Note the co-existance of fluid and dried milk for the same application and mull the reasons behind this fact. This author has seen a variety of non-dairy milks and powdery whiteners in the US, aimed mainly at countering lactose-intolerance.

  1. The common utility of milk powder: (i) The dairy whitener is popular in western markets and on airplanes.

Image by <a href="https://www.freepik.com/free-photo/arrangement-natural-spa-sand-bowls-top-view_10753463.htm#query=protein%20powder&position=19&from_view=keyword&track=ais_user&uuid=95f608fd-6f59-4bb7-aefa-38ef4e6a7c78">Freepik</a>(ii) Marketers routinely exploit its inherent nutritive value and abundant availability to increase the nutritive profile of commercial high-protein powders. Some day, we will look at how to make such a product at home.

(iii) It is similarly used to formulate brown, cocoa-based beverage powders – their main nutrition contributor – which make tall claims about what they can do for children.

(iv) Sweetmeat-makers (halwai’s) use it extensively in sweet-making to reduce the evaporation loads and hasten up production. Pedhe, barfi’s, halwa’s, kaju katli, gulab jamuns, kala jamun, kala kand and generally all mawa-based sweets exploit milk powder. In fact, ‘instant gulab-jamun premixes’ are nothing but milk powder with some baking soda and refined flour or semolina or suji. (After a few years of making Gulab Jamuns with milk powder, we have now embraced the Gulab of health by avoiding it.)  This explains the shortage of milk powder in consumer packs in the market as Diwali approaches.

( Note: The aforesaid white khoya reconstituted from milk powder and milk will quickly convert to brownish home-made khoya simply by lightly roasting it with a pinch of sugar in a pan. When using sweetened condensed milk for this, skip the sugar. Though limited, such brownish sweet khoya with a slight burnt flavor has its own market.)

Let us now take up some simplified cost-benefit analysis of using milk powder at home with the express purpose of introducing the concept of ‘environmental cost of processing’.

Next post: Replacing milk with milk powder in home cooking

Introducing: the environmental cost of food processing

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