Building a crunchy shell on nuts
A crunchy nut is a nut delivering the crunch of a light biscuit in addition to the nut itself. Having the appearance of baked biscuits results in fact from a panning and roasting process.
The core is a nut – typically a peanut. Small-size nuts are preferred as coating increases substantially the overall size of the nut.
Different bites can be offered : a hard but shallow coating or a light and thick coating depending of the expansion of the biscuit.
The raw nuts are first coated with a slurry acting as a glue.
This slurry is simply water or a glue made of hydrocolloids which have filming and adhesive properties such as:
- Glucose syrup
- Gum Arabic
Then a flour mix is added to build up the biscuit layer. It is composed of:
- Taste enhancers such as glutamate, yeast extract
- Native flours such as rice, maize, or wheat to give body
- Pre-cooked or modified starch to promote the expansion of the biscuit
- After frying, the coated nuts receive a flavouring mix.
How does it work?
The process is typically a wet panning process where layers are successively built on the centre. Roasting removes the moisture and cook the starch. Dry flavouring completes the product. The process and the ingredients may vary to provide a different aspect and taste : Japanese, Lebanese coated nuts. For example, Lebanese-style coated nuts are first roasted then coated with a suspension of starch, the residual heat cooks the starch and extracts the moisture; spices and flavours can be added in the process.
The coating process runs as follows
Introduction of the nuts in a rotating pan
Application and dispersion of the slurry on the nuts by the rotating motion
Application of the flour mix on the wet nuts and dispersion. The thichness of the coating biscuit is increased by repeating the 2nd and 3rd steps
Transfer into a hot air roaster or an oil fryer which completes the coating operation, cooking the flour and expanding the biscuit
Transfer into a pan where various flavours are applied in smaller batches.
The successive liquid and powder applications occur in a rotary pan or drum.
The slurry is simply dripped over the nuts and dispersed by the motion.
The flour mix is dosed.
Depending of the size of the batches, the liquid and powder applications are done manually or mechanised with pump and feeder respectively.
As the powder tends to set quickly on the wet surface and form agglomerates, it is recommended to disperse the powder finely and progressively over the nuts.
Cooking may be done in batch or continuously.
Depending on the throughput and frequent recipe changes, there are many options. Coating pans are generally used, from small to large sizes. They come with baffles to enhance the tumbing motion of the products. Mechanical liquid and powder dosing devices are added, possibly automatized.. The most advanced solution consists in a tumbling system where nuts are processed continuously. The design displays sections, through which the nuts progress, where liquid or powder can be successively applied. Illustration : CN300 continuous nut coater, courtesy of Kuipers Food Processing Machinery NL
How do you measure your success?
Key quality features
The product is a combination of features
Peanut is a standard. Small and even size is used. Not split
Crunchy as biscuit, holding firmly to the core
Adheres to the coating
Key quality parameters
Some aspects of this type of coating are critical
Surface tension and viscosity are critical to offer a sticky layer to the powder
Adhesive and expansion properties of the flour mix; flours provide a better expansion when previously cooked or modified
Timely and quantitative control of the liquid and powder addition to prevent excessive humidity, agglomeration, ingredient losses