Thursday, February 17, 2005

Acai Study Continued

4. Sugars

The assimilatable sugar content in Açai fruit is generally normal, with sucrose (present mainly in pineapple, pears, citrus fruit and bananas) and the glucose monomers and fructose (mainly present in kiwis, cherries, apples, plums and grapes) constituting the forms most commonly found. These sugars come from progressive starch degradation, normally abundant before maturity (Kader & Barrett, 1996).

The detailed analysis of these sugars by liquid chromatography shows the presence of glucose and fructose (1.55% and 1.36% respectively in relation to dry matter). The glucose and fructose contents do not present any significant difference among trees, shoots and conditions (p > 0.05). Sucrose is almost absent from the product (0.05% of the D.M.). The presence of starch was not detected.

5. Fibers

The fiber content varies widely from one fruit species to the other. In the case of Açai, the total food fiber concentration is notably high (25.22% of dry matter on an average) (Table 2) and make them the second largest quantity of compound in cabbage palm after lipids. Part of these fibers can easily be seen by optic microscope. The fibers do not present any significant difference of content for the factors trees, shoots and conditions (p > 0.05).

Fibers play a very important role in regulating the consumer’s intestinal transit, as well as participating in the prevention of colon cancer. The daily recommended intake of total food fibers is 35g per adult. Therefore, Açai may really be considered to be an excellent source of fibers. Further studies should be developed to characterize these fibers.

6. Vitamins and Minerals

6.1. Vitamins

Costa (1953), for the first time, showed the presence of vitamin B in Açai, using it to1 enrich the feed for pigeons that lacked this vitamin . Vitamin B (0.25 mg/100g D.M.) is 2 frequently present in significant amounts in oleaginous plants.

6.2. Major Mineral Elements

Potassium is the most abundant mineral in the Açai (990 mg/100g D,M.). High contents of this mineral in foods are frequently associated with an easily growing acidity and/or an improved color.

2 - For man, extreme lack of vitamin B, causes beriberi, a disease characterized by cardiac and nervous disturbances, muscular atrophy and edemas (Domart & Bourneuf, 1981)

The weak sodium content (76 mg/100 g D.M.) finds its origin in the richness in potassium.

Calcium is the second most abundant mineral in the Açai and is associated with the cell wall structures (Kader & Barrett, 1996).

The magnesium found in fruits originates in the chlorophyll present before maturity. On an average, the content is of 178 mg/100 g D.M.

With regard to phosphorous, it is a citoplasmatic and nuclear constituent of proteins and plays an important role in carbohydrate metabolism and energy transfer (Kader & Barrett, 1996). The mean quantities of this mineral in Açai are 147 mg/100 g D.M.

6.3. Oligo-elements

The copper content is very high for a fruit (1.38 mg/100 g D.M.) and the Açai may therefore, be considered to be an excellent source of this oligo-element. In effect, the daily recommended consumption is 1.1 mg for an adult (CNNB, 1996).

The manganese content (32.3 mg/100 g D.M.) is excessive in relation to the daily required quantity (10 times more) but does not get to be toxic, as the manganese causes disorders at much higher concentrations (above 200 mg/day) (Belitz & Grosch, 1992).

The zinc content (1.73 mg/100 g D.M.) is below the values found by other authors (2

-7 mg/100 g D.M.) and should, in all cases, be considered as low for a food.

The cadmium (460 ppm of D.M.), and boron (1.58 mg/100 g D.M.) and nickel (203 ppm of D.M.) had never been dosed before.

It is also mentioned that Almeida & Valsechi (1966) dosed the aluminum and obtained a value of 2.6 mg/100 g of dry matter, normal for this type of food.

The Anthocyanines

The mean content is 440 mg/kg of fruit (Table 2). Expressing the anthocyanine content in 100 g of dry extract, a mean value of 1.02 g is obtained, which means to say that around 1% of the dry matter is made of these powerful anti-oxidants. It was seen that other products contain comparable contents (Table 5).

Table 5 Concentration of anthocyanines in various foods

Common name
Scientific name
Concentration

Açaí
Euterpe oleracea
440mg/100g fruit

Cranberry
Vaccinium corimbosum x V. macrocarpon
330-535mg/100g

Cherry
Prunus cerasus
43.6mg/100g

Red cabbage
Brassica oleracea var. capitata
25mg/100g

Strawberry
Fragaria chiloensis
15-35mg/100g

Raspberry
Rubus idaeus
40mg/100g fruit

Gooseberry
Ribes nigrum
145mg/100ml

Black beans
Phaseolus vulgaris
213mg/100g

Juçara
Euterpe edulis
134.7/100g fruit

Mulberry
Rubus occidentalis
345mg/100g fruit

Red onion
Allium cepa
9-21mg/100g

Apple (skin)
Malus pumila
0.03mg/cm2

Plum (skin)
Prunus domestica
29.5mg/100g fruit

Black grapes
Vitis vinifera
65-140mg/100g

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