Introduction
Potato (Solanum tuberosum L.) is the single most important non-cereal crop grown in about 150 countries. India ranks second for potato production globally.
Potatoes are mostly consumed as fresh and about 68.5% goes as table consumption in India. However, it is 31% in case of major developed countries, remaining being used for making frozen French fries (30%), chips (12%) and other dehydrated products (12%).
As compared with developing countries, Indian food processing industry merely uses about 4% of total potato produced. Processed potato food product market is increasing day by day but due to changed habit of consumer preference towards storability, taste, texture of finished product, more attention has been given to the quality of fried and dehydrated products.
Varieties of ready-to-cook, ready-to-eat and heat-and-eat products are accessible in the market in huge quantity for the consumers. Potatoes can be used for making diversified products such as fries, chips (dehydrated chips also), dice, cubes, papads, flakes, potato starch, granules and potato flour.
In India, potato chips attract all sections of society, which makes 85% of total Rs 2,500 crore salty snacks business. This sector is still in nascent stage and is expected to rise at least upto 3.55 MT by 2050. Indian potato snacks have a huge range and widely accepted because of their flavour and taste.
Fate of food is determined by its taste. Hot oil as a medium of frying is a deciding factor for texture and taste of fried products. Various processing methods give different flavours and textures to potato products, which in turn decide the product acceptability.
Both, volatile and non-volatile compounds are responsible for flavour of potatoes. Umami compounds are major non-volatile compounds responsible for flavour to potatoes. As we know, Umami is fifth basic taste. Glutamate and aspartate and 5' nucleotides viz. adenosine 5' monophosphate (AMP) and guanosine 5' monophosphate (GMP) are major umami compounds. Flavour of potato products depends upon potato variety (cultivar) and method of processing. Umami compounds are responsible for meaty and savoury flavour. Sugars, RNA, lipids act as flavour precursors in raw potatoes. They react and produce Maillard reaction compounds while degradation products of lipids, RNA and sugars are responsible for final product flavour.
Glutamate and guanosine 5' monophosphate contribute majorly to flavour among other umami compounds. Sodium, potassium and magnesium salts enhance the intensity of umami compounds. People have used Guanosine 5' monophosphate and inosine 5 monophosphate with Monosodium glutamate synergistically to produce food products with enhanced flavours.
Saltiness in food products are increased by using umami compounds. Potato tubers contain 5 ribonucleotides in large amounts as flavour precursor. During cooking, 5 ribonucleotides are released by enzymatic hydrolysis of RNA.
Potato has characteristic bland flavour due to which it has widespread acceptance. This bland flavour helps to make different food products for diversified population. Potato variety, soil mineral composition, fertilisation are responsible for raw potato volatile composition which affects potato flavour.
Potato chip is very popular potato-based snack product containing various volatile compounds such as aldehydes (e.g., acetaldehyde, propanal, butanal, hexanal), hydrocarbons (e.g., heptanes, nonane, decane), pyrazines and acids. During storage, pleasant aroma forming ethanol and diacetyl reduce with increase in propanal, hexanal, pentanal, 2-pentanone, 2-propanone, 2-heptanal, and 2-octenals.
Pyrazine, 2-ethyl-3,6-dimethylpyrazine responsible for potato chips aroma along with other 16 pyrazines and 2 pyridines and methional, 3-methylbutanal, phenylacetaldehyde, and 2,4-decadienal. French fries are also one of the popular potato snacks. Flavour to the French fries results due to oil used for frying and potato variety. During frying, volatile fatty acids from oil migrated to the product surface causing change in fatty acid profile of French fries.
Extrusion cooking is well known method to manufacture low fat potato snacks. During extrusion, various reactions such as oxidation, hydrolysis occurs in the barrel along with Maillard reaction responsible for the development of the characteristic colour and flavour to the final product.
Benzenemethanethiol, methional, 2-acetyl-1-pyrroline, butanal, and phenylacetaldehyde compounds are responsible for flavouring in extruded snacks. After extrusion, drying step is most crucial for resulting texture, crunchiness, golden colour with full flavour. Potato granules can also be used to manufacture low fat snacks with better flavour profile as per studies.
It can be concluded that potato varieties and the processing methods develop the characteristic flavours of potato processed products. Addition of salts helps to develop a desirable flavour in snacks.
(Dr Singh is Assistant Professor at Department of Food Science and Technology, Chinchkar is research scholar at National Institute of Food Technology Entrepreneurship and Management (NIFTEM), Sonipat. They can be contacted at anurag.niftem@gmail.com)