At the end of the day, it doesn’t matter how big the fruit or how perfect the skin if the passionfruit doesn’t taste good. Testing the eating quality of your fruit should be a critical part of your Quality Assurance program.
How can you assess the flavour?
- Taste-test your fruit on a regular basis so you can assess how the flavour and sweetness changes over time
- Taste fruit from different parts of your orchard side by side so you can determine any major flavour differences which can highlight a nutrition shortfall in parts of your orchard
- Use a refactometer to objectively assess the Brix or dissolved solids in your fruit
Where can you buy a refractometer?
- The simplest option is to buy one online from a mass retail site like eBay or Amazon
- Your farm supplies retailer may also be able to provide one, although this is likely to be a more expensive model than those found online
How does a refractometer work?
- When light enters a liquid it changes direction; this is called refraction
- Refractometers measure the degree to which the light changes direction, called the angle of refraction
- A refractometer takes the refraction angles and correlates them to refractive index (nD) values that have been established
- Using these values, you can determine the concentrations of solutions. For example, solutions have different refractive indexes depending on their concentration
- The prism in the refractometer has a greater refractive index than the solution
- Measurements are read at the point where the prism and solution meet
- The % Brix Scale shows the concentration percentage of the soluble solids content of a sample (water solution)
- The Brix scale is calibrated to the number of grams of cane sugar contained in 100 g of water
- When measuring a sugar solution, the % Brix reading should perfectly match the actual concentration