Fruit hardness is the universally accepted measure of fruit ripeness. The fruit Penetrometer accurately measures fruit hardness by measuring the force required to push a plunger tip (of a certain size) into fruit and vegetables.
The GY series of Penetrometers are ideal for testing a wide range of fruits and vegetables. The force measurement provides the necessary information for growers to determine the best picking time, and to monitor fruit ripening and softening during storage.
Naturally, different fruits and vegetables will vary: varieties, geographical location and climate will all affect the appropriate firmness for picking a particular fruit. Recommended measurements are used as a guide, the growers using their experience and expertise to establish the precise firmness value applicable to their particular variety and environment.
| The importance of measuring the firmness of fruit for testing maturity. |
| To talk about the maturity of fruit, its important to distinguish between physical maturity and commercial maturity. Physiological maturity can only transpire while the fruit is still on the plant and is the last moment when the fruit can be picked to be sold. Commercial maturity occurs later, and indicates the best time to consume the fruit, when its colour, flavour and texture are ideal for the consumer. In the case of the climatic fruit, the commercial maturity of the fruit can occur sometime after it has been picked.
While fruit is maturing, important changes occur inside, such as changes in colour, form and texture. It’s important to have objective values available with those that evaluate the changes in the fruit as it matures, to allow for decisions to be made as to when the fruit should be picked and processed (to determine the quality of fruit from the moment it becomes a product to its final consumption). The firmness of the fruit, measured by the penetrometer, one of the most objective parameters in relation to the fruits maturity and as such is one of the most common techniques used in testing. Other methods are to determine the colour or the content of soluables using a refractometer (this technique is proportional to measuring total sugar and thus the sweetness of the fruit). If you are looking for refractometers to measure the sugar content of fruit, you can see them at this link. Generally, the firmness or hardness of fruit measured by a penetrometer decreases as the maturity process occurs. Of course, you have to take into account that the firmness of the same fruit can vary, in general terms such as fruit variety or the region where it is cultivated, or due to its size or the temperature of the fruit when it is being measured by the penetrometer (the higher the temperature, the less firm the fruit is). |
Penetrometers are used by fruit growers worldwide to help determine the harvest times for plums, navel oranges, nectarines, kiwifruit, peaches, and other varieties or stone or pome fruit. This penetrometer is the standard used by fruit growers for decades.
The plunger of the unit is pressed against the fruit and measurements of the rupture pressure can be seen on the gauge. Different varieties will have different rupture points. Can be used hand held or can be mounted on a drill press for additional accuracy.
Each unit comes with appropriate tips, a foam lined carrying case, a protective splash plate, a fruit peeler, a manual and recommended pressure test readings for specific fruits are including with each penetrometer. All units come with a one year “unconditional warranty.”
Vegetable hardness is a very important index in the quality control process. The main advantage of this instrument is that it is non-destructive. This means it has these advantages:
- The maturation level of fruit can be monitored throughout the plant’s entire growth cycle;
- Measurements can be carried out on the products where the classic fruit pressure tester (a destructive instrument) do not give acceptable results.
The instrument is very simple to use: once taken the instrument, place the plunger against the fruit and progressively press until the fruit is completely against the grey basement of the plunger.
For a more meaningful control it is necessary to take various samples of fruit. Two measurements must be carried out on each piece of fruit – on the opposite side of the fruit.
The determined value, average of the two measurements, is expressed in Shore degrees, range of reference for the hardness of a material.
