On the market, there are many different types of fruit juices.
Their differences can be in the type of raw material, composition, fruit content, packaging method.
Simply described, juice are poly disperse system that differ from each other in terms of fruit particle size and their solubility in water [1].
According to the current legal "Regulations on fruit juices and nectars and related products" (NN 48/2013), fruit juices are divided into:
Product that can ferment, but is unfermented. It is produced from the edible part of a fruit that is healthy, fresh or preserved by cooling or freezing one or more types mixed together and has a color, aroma and taste characteristic of the fruit juice from which it originates.
It is produced by reconstituting concentrated fruit juice with drinking water that meets the criteria prescribed by the Ordinance on the Healthiness of Drinking Water. The soluble matter content of the final product must meet the minimum Brix value for reconstituted juices.
It is produced from the fruit juice of one or more types of fruit by physically removing a certain amount of water. If the product is intended for the final consumer, the amount of water removed should be at least 50%.
It is produced by diffusion with water from:
– the pulp of the whole fruit whose juice cannot be extracted by any physical process, or
– dehydrated whole fruit.
It is produced from the fruit juice of one or more types of fruit by physically removing almost all of the water.
It is produced with the addition of a certain amount of water and sugar and/or honey.
Chemical compostion of fruit-based drinks is very important and it is controlled by checking the dry matter content.
Content of dry matter is measured using optical device, a refractometer. It is the amount of soluble ingredients.
The bottom limit is prescribed and if there are no changes in the content of all components it can be assumed that the product has its original properties.
Minimum content of dry matter:
- for fruit juices 12%,
except for apple 10% and grape 15% - concentrated fruit juice 45%,
except concentrated lemon, strawberry and raspberry juice 32%
An exception is made for concentrated lemon, strawberry and raspberry juices:
– for lemon due to the high content of acids, which at higher concentrations have a negative effect on the composition;
– strawberries and raspberries, instead, contain very sensitive colored substances so, when heated for a long time, they lose its color during concentration.
The sugar content, which makes up the largest part of the dry matter, is also an indicator quality [table 1]:
| Common name of the fruit | Botanical name of the fruit | Lowest value of Brix degrees |
|---|---|---|
|
Apple
|
Malus domestica Borkh. |
11,2 |
|
Apricot |
Prunus armeniaca L. |
11,2 |
|
Banana |
Musa x paradisiaca L. (izuzev bananica) |
21,0 |
|
Blackcurrants |
Ribes nigrum L. |
11,0 |
|
Cherry |
Prunus cerasus L. |
13,5 |
|
Grape |
Vitis vinifera L. ili njihovih hibrida Vitis labrusca L. ili njihovih hibrida |
15,9 |
|
Grapefruit |
Citrus x paradisi Macfad. |
10,0 |
|
Guava |
Psidium guajava L. |
8,5 |
|
Lemon |
Citrus limon (L.) Burm.f. |
8,0 |
|
Mango |
Mangifera indica L. |
13,5 |
|
Orange |
Citrus sinensis (L.) Osbeck |
11,2 |
|
Passion fruit |
Passiflora edulis Sims |
12,0 |
|
Peach |
Prunus persica (L.) Batsch var. persica |
10,0 |
|
Pear |
Pyrus communis L. |
11,9 |
|
Pineapple |
Ananas comosus (L.) Merr. |
12,8 |
|
Raspberry |
Rubus idaeus L. |
7,0 |
|
Strawberry |
Fragaria x ananassa Duch. |
7,0 |
|
Tomato |
Lycopersicon esculentum, Mill. |
5,0 |
|
Tangerine |
Citrus reticulata Blanco |
11,2 |
Table 1 – Minimum values of Brix degrees for reconstituted fruit juices and reconstituted fruit pules
Determination of Brix value in berries
Use of refractometer
Refractive Index is an optical characteristic of a substance and the number of dissolved particles in it.
Refractive Index is defined as the ratio of the speed of light in empty space to the speed of light in the substance.
A result of this property is that light will “bend”, or change direction, when it travels through a substance of different refractive index. This is called refraction.
When passing from a material with a higher to lower refractive index, there is a critical angle at which an incoming beam of light can no longer refract, but will instead be reflected off the interface.
Refractometer can convert the refractive index of a food sample to % brix.
The procedure is as follows; sample, a few drops are placed on the designated spot on the digital refractometer and the result is read.
A refractometer is required every time before measurement, test with distilled water whose percentage of dry matter is equal to zero.
HI96801
Digital Refractometer for Brix Analysis in Foods
The HI96801 is a rugged, portable digital refractometer for food products designed to report the sugar content of aqueous solutions as % Brix with an accuracy of ±0.2% Brix.
The operation of the meter is simplified with only two buttons: one button is to calibrate with distilled or deionized water and the other to take a measurement.
All readings are automatically compensated for temperature variations according to the ICUMSA Methods Book standard and displayed within a 1.5 second response time.
The sealed flint glass prism and stainless steel well are easy to clean. Just wipe with a soft cloth in preparation for the next sample.
- Sample size as small as 2 metric drops (100 μl)
- Sealed stainless steel well with high-grade optical prism made of flint glass
- Fast 1.5 second response time for temperature compensated readings
Have questions?
Contact a Hanna Technical Specialist at [email protected] or using our contact form.
Author:
Tajana Mokrović
mag.nutr.
- Ashurst, P., Hargitt, R. (2009): Soft Drink and Fruit Juice Problems Solved, Woodhead Publishing, Cambridge.
- Pravilnik o voćnim sokovima i nektarima te njima srodnim proizvodima, Narodne Novine, br. 152/05.
- Tetra Pak (2009): From fruit to the packaged product, Tetra Pak Magazine, 97, 26-34.
- Pravilnik o voćnim sokovima i njima sličnim proizvodima namijenjenim za konzumaciju, Narodne Novine, br. 48/2013
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