22 
BULLETIN 1265, U. S. DEPARTMENT OF AGRICULTURE 
Table 3. — Analyses of Stringless Green Pod string beans, before and after 
treatment. 
[Each result is the average of three samples.] 
Average constituents (per cent) . 
Treatment of material, if any. 
Mois- 
ture. 
Solids. 
Alcohol. 
Sugars. 
Poly- 
sac- 
cha- 
rides, 
as 
starch. 
Pento- 
sans. 
Nitro- 
Solu- 
ble. 
Insol- 
uble. 
Re- 
duc- 
ing. 
Nonre- 
duc- 
ing. 
Total. 
gen, 
as 
pro- 
tein. 
Xo treatment ... 
89.40 
89.60 
89.52 
90.05 
90.83 
90.43 
90.76 
10.60 
10.40 
10.48 
9.95 
9.17 
9.57 
9.24 
4.46 
4.38 
4.38 
4.15 
3.73 
3.75 
3.61 
6.14 
6.02 
6.09 
5.80 
5.44 
5.82 
5.53 
2.34 
2.39 
2.28 
2.01 
1.78 
1.97 
1.80 







2.34 
2.39 
2.28 
2.01 
1.78 
1 97 
1.80 
2.60 
2.58 
2.63 
2.52 
2.33 
2.67 
2.35 
1.15 
1.72 
Treated 4 minutes with live 
steam . ... .. 
1.71 
Treated 8 minutes with live 
steam 
1.73 
Scalded 4 minutes in boiling 
water. .. 
1.65 
Scalded 4 minutes in boiling 
water and then chilled 30 
seconds in cold water 
Scalded 8 minutes in boiling 
1.63 
1.64 
Scalded 8 minutes in boiling 
water and then chilled 30 
seconds in cold water 
1.48 
The composition of string beans is strikingly different from that 
of peas. They have considerably more moisture, relatively little 
starch, but a much smaller total of polysaccharides than peas. In- 
stead of cane sugar, as in peas, the sugars are all reducing sugars. 
Beans contain a comparatively high percentage of pentosans, which 
are of such a nature as to require long cooking to make the beans 
tender. 
Comparison of the figures for the fresh green beans and those 
that had been scalded shows that treating with live steam causes 
practically no change in the chemical composition of the beans. 
Scalding in water alters the composition somewhat, there being an 
increase in moisture content and a small loss of soluble constituents. 
Apparently, no changes occur in the chemical composition of string 
beans during scalding which would not take place anyway during 
the subsequent processing. 
Prolonged cooking gradually softens the tissues, due to the changes 
in the middle lamellae and other cell structures containing pento- 
sans. The use of sodium carbonate or other alkalis hastens this 
action, owing to the solvent action of the chemicals upon the pectic 
substances in the tissues; but, as in the case of peas, where calcium 
and magnesium compounds, or other of the alkaline earths, are 
present in appreciable quantities in the water used, the action is to 
harden the tissues rather than make them tender, due to the forma- 
tion of insoluble pectates of the alkaline earths. 
CONCLUSIONS REGARDING THE SCALDING OF STRING BEANS. 
So far as appears, the chief advantages from scalding string 
beans before canning are the reduction in bulk and increased flexi- 
bility of the beans, which make possible a full and attractive pack. 
and the desirable effect produced on internal pressure and vacuum. 
These are so important that scalding in some form seems to be of 
