Joywhite

[CHARACTERISTICS] Skin is light yellow; flesh is white. Spindle shaped with a swollen upper end, or spherical. Shape tends to be slightly irregular. Contains hardly any beta-amylase; sweetness is not increased by cooking. In terms of the starch whiteness, "Joywhite" is superior to "Koganesengan," but the two are equal in terms of blackening when steamed, polyphenol content, and polyphenol oxidase activity. When used as a material for shochu (distilled spirit), gives a nice flavor. Seen as a very promising material for shochu. [APPLICATIONS] Processed foods and shochu [EXAMPLES OF PROCESSED FOODS] Imojochu having a natural fruity flavor

Data of Characteristics

　

1. Advantages	2. Disadvantages
Especially high suitability for Shochu brewing High protein yield Strong resistance to root-knot nematodes Good storability	Slightly inferior to the Koganesengan in yield Moderate resistance to black-spot disease

3. Characteristics comparison

Characteristics		Joywhite	Koganesengan	Satsumahikari
Tuber shape		Spindle shaped	Spindle shaped, with a swollen lower part	Long and spindle shaped
Tuber skin color		Faintly reddish white	Yellowish white	Red
Tuber flesh color		White	Yellowish white	Yellowish white
Tuber appearance		Better	Medium	Better
Steamed sweetpotato	Brix (%)	2.2	4.4	2.3
	Polyphenol content	51mg%	47mg%	40mg%
	Blackening	Medium	Medium	Slightly weak
Resistance to diseases and insect pests	Black rot disease	Medium	Slightly weak	Medium
	Root-knot nematode	Strong	Slightly weak	Strong
	Root-lesion nematode	Slightly strong	Slightly weak	Medium
Storability		Somewhat easy	Somewhat difficult	Medium

4. Harvest findings

	Joywhite		Satumahikari		Koganesengan
Cultivation area characteristics (year)	Harvest kg/a(%)	Starch yield(%)	Harvest kg/a(%)	Starch yield(%)	Harvest kg/a(%)	Starch yield(%)
Cultivation area (1989-1993)
Standard cultivation	187	25.3	171	20.9	226	22.6
Early-harvest cultivation	150	24.0	134	19.0	195	21.2

5. Brewing test

Fiscal year 1990	Joywhite	Comprehensive evaluation 1.55	Fruity, light, sweetness, sweet flavor, splendid aroma
	Koganesengan	Comprehensive evaluation 1.80	Mellow, light, thin, clean, ester, starchy smell
Fiscal year 1991, 1992	Joywhite	Short comment	Sweet flavor, unique flavor, sweetness, natural, clear, agreeable to drink.

[Note] Comprehensive evaluation: Average value of 1 for good, 2 for average and 3 for poor.