Minimally Processed Foods : Fruit and Vegetables

 

Vegetable juice

 

 

In Europe, vegetable juices are not consumed in the quantity that fruit juices are. The most popular among them is tomato juice, or cocktails with tomato juice.
Like fruit juices, there are clear juices and cloudy juices that contain pulp. Also like fruit juices, the richest and healthiest are those that contain the highest proportion of the original vegetables. In addition, there are products fermented with lactic acid that address still other aspects of health.


Although the terminology for vegetable juices is not as strictly regulated by law as is the case for fruit juices, there are, in addition to fresh, not-from-concentrate vegetable juices, also pulps, raw and homogenized juices and concentrates. These are also known as semi-finished products and are prepared primarily in order that juices can be produced all year round from vegetables that are not always in season. In principle, these terms are the same as those that describe fruit juices. A homogenate is vegetables that have been precooked and pureed, possibly with water added. It could also be called vegetable mash or vegetable pulp. Mixtures of different juices are called vegetable cocktails.


In contrast to fruit juices, ingredients to enhance the flavour of vegetable juices are permitted. Among these are salt, vinegar and other edible acids, sugar, spices and herbs.

Manufacture

Only healthy, ripe, freshly harvested and unspoiled raw materials may be used to make vegetable juices. This serves not only to protect consumers from health risks; it is also intended to preclude the loss of sensory quality which might occur, for instance, if wilted vegetables were used: The enzymes they contain can alter the ingredients of the juices so that an undesired off-taste emerges or the colour changes.

With all processes for manufacturing vegetable juices it is important that they take place as quickly as possible and with maximum cleanliness, preferably in the absence of air. Vegetables are frequently exposed to many bacteria and putrefactive agents even prior to processing, and after they are harvested the danger of infestation is also great. Therefore, a particularly effective method of preservation must be used as well. In this light, the production of lactic-acid-fermented juices is relatively simple, since an acidic pH value partially curbs the growth of micro-organisms. The best-known of these juices is surely sauerkraut juice, but carrot, beetroot, celery and tomato juices are also in some cases fermented with lactic acid.

The processing steps from vegetable to juice are basically the same as for fruit. Naturally, there are additional steps for cleaning or peeling specific to each vegetable, and additional procedures for preservation.

There are two methods for producing lactic-acid-fermented vegetable juices: natural fermentation and lactofermentation. For natural fermentation, the vegetables must be cleaned and chopped. Then they are layered in a container, each layer alternating with salt, with no air allowed to remain in the spaces between the layers. The containers are then sealed so that no air can get in, and a high pressure is built up. After several days the fermentation begins by itself and is completed after a longer period of time. Following fermentation, the juice is pressed, centrifuged, deaerated and pasteurised.


Lactofermentation is more suitable for most types of vegetables. Fermentation takes place faster and under more controlled conditions. The vegetables are first washed and chopped, briefly heated in order to kill micro-organisms and inactivate enzymes, and then cooled. Instead of waiting for fermentation to begin naturally, starter cultures with lactic-acid bacteria are added. Fermentation is completed after 18 hours and the mash can be pressed. In this method the juice is also centrifuged, deaerated and pasteurised. Lactic-acid fermented juices produced in this way are low in salt and thus well-suited for dietetic purposes. Lactic-acid fermented vegetable juices can be stored and further processed throughout the year.

Ingredients

All vegetable juices are low in calories. They are also rich in many minerals and vitamins and contain many aromatic substances.
In addition, lactic-acid fermented juices have a positive effect on heart and circulatory disorders, diabetes, arteriosclerosis and other diseases.

On average, 100 ml contain:

 

Carrot juice

Beet juice

Sauerkraut juice (lactic-acid fermented)

Spinach juice

Tomato juice

Energy (kcal)

22

36

15

9

17

Water (g)

92.7

88.4

n.a.*

95.4

94.2

Protein (g)

0.6

1

1

1.4

0.8

Fat (g)

traces

traces

traces

0.1

0.1

Carbohydrates (g)

4.8

8

1

0.5

2.9

Fibre (g)

traces

traces

traces

n.a.*

0.1

Vitamin A (RE) (µg)

437

traces

3

n.a.*

150

Vitamin B1 (µg)

traces

traces

n.a.*

10

50

Vitamin B2 (mg)

traces

traces

n.a.*

80

40

Vitamin B6 (µg)

traces

traces

n.a.*

n.a.*

110

Vitamin C (mg)

4

3

8

29

17

Vitamin E (TE) (mg)

traces

traces

0.2

n.a.*

n.a.*

Folic acid (µg)

5

38

7

32

16

Niacin (mg)

traces

traces

n.a.*

0.2

0.7

Sodium (mg)

52

200

547

73

5

Potassium (mg)

219

242

267

412

230

Calcium (mg)

27

2

49

1

15

Magnesium (mg)

traces

traces

0.6

1.5

0.6

Iron (mg)

traces

traces

0.6

1.5

0.6

* n.a. = no data available, RE = retinol equivalent, TE = tocopherol equivalent

Optimal storage

The same holds for vegetable juices as for fruit juices: To avoid the loss of vitamins, colour and aroma, juice products should be kept for only a short time and in a cool, dark environment. After they have been opened they should be kept in the refrigerator and used up within several days. They should not be too cold when they are drunk, however; the aromas develop better at warmer temperatures.

 

 


 

  With the website www.the-green-pantry.com the Fritz Terfloth Foundation of Münster offers consumers independent and competent information about plant foods and their health effects. All texts are subject to German copyright law. Information about the conditions for use of the texts by third parties can be found here.