The weight of potatoes in water: Further studies on the relation between the dry matter and starch content
Tóm tắt
The weight in water (m
u
) of 100 g air-free potatoes multiplied by the dry matter factor (K) equals the percentage dry matter (m
t
) in the tubers. The weight in water is unaffected by the water in the potatoes but is reduced by air in the intercellular spaces and must be corrected for this by a constantk. From the specific gravity of the dry matter the factorK is estimated as 2.50. From the weight in water and the percentage of dry matter estimated by oven-drying of 5.413 samples between 1937 and 1964.K is also estimated as 2.50. The amount of air in potatoes varies. In 1.911 samples examined between 1937 and 1948 air reducedM
u
on average by 0.8g, therefore,m
t
(m
u
+0.8)·2.5 orm
t
·m
u
2.5–2.00., In 2,732 samples examined between 1952 and 1964 the reduction was 0.6 g therefore,m
t
—(m
u
—0.6) 2.5 orm
t
·m
u
·2.5+1.5. The percentage dry matter can be calculated more exactly from the weight in water of potatoes from which the air has been evacuated by immersing the tubers in water in a closed container and subjecting to vacuum (50–20 mm Hg) for about 30 minutes.
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