Options for Storing Potatoes at Home
Options for Storing
Potatoes at Home by Lynn Woodell, Nora Olsen a nd Jim Wilson
Pota toes a re a na tura lly hea lthy food. One m edium -sized pota to is fa t free, cholesterol free, sodium free, provides 110 ca lories, is a n excellent source of vita m in C a nd a good source of pota ssium (see figure 1—nutrition la bel).
Consum ers often ha ve questions a bout storing pota toes in the hom e to m a inta in tuber qua lity. If you buy a few pota toes to use within da ys, the stora ge loca tion is not a n issue—you ca n keep them a lm ost a nywhere. But if you intend to store severa l to hundreds of pounds of pota toes for a s long a s possible, the stora ge loca tion ca n a ffect how long the pota toes rem a in usa ble.
To identify the perfect hom e stora ge loca tion in your house, first a nswer three questions: Wha t kind of pota toes a re they? How long do you intend to store them ? How do you intend to cook the pota toes—will you ba ke, fry, or boil them ?
Your a nswers will help you decide where to store pota toes a t hom e.
What are the is s ue s with s toring potatoe s at hom e ?
Even a fter ha rvest, pota toes a re still living, respiring orga nism s tha t use oxygen a nd give off ca rbon dioxide. This m ea ns pota to tubers m ust ha ve fresh a ir for prolonged stora ge. The fa ct tha t they a re a live a lso m ea ns tha t they respond to their environm ent. Wa rm tem pera tures encoura ge sprouting a nd tuber disea ses. Pota to tubers exposed to light will turn green. Tubers stored in a dry environm ent will becom e fla ccid a nd withered in a ppea ra nce. The best pla ce to store pota toes is in a ventila ted, cool, da rk, a nd hum id environm ent.
Figure 1 . USDA Nutritional Facts
University of Idaho • College of Agricultural and Life Sciences Temperature Humidity
Most hom es a re kept a t tem pera tures between
65 to 75°F—m uch higher tha n the idea l stora ge tem pera tures for a pota to (42 to 50°F). The wa rm er tem pera tures of a typica l hom e ca n eventua lly lower the qua lity of your pota toes, if they a re stored a t room tem pera ture. Wa rm tem pera tures encoura ge the growth of disea se-ca using orga nism s tha t would typica lly be inhibited a t cooler tem pera tures. Higher tem pera tures a lso encoura ge pota toes to form sprouts m ore quickly tha n lower tem pera tures. In genera l, a pota to will na tura lly begin to form sprouts 30-140 da ys a fter ha rvest, depending on the va riety. Pota toes purcha sed from a reta il m a rket m a y dela y sprouting even longer due to m ethods tha t ha ve been used to control sprouting prior to pa cka ging.
Pota toes conta in a pproxim a tely 80% wa ter a nd therefore need to be stored in a hum id loca tion to prevent them from drying out. Storing pota toes in a dry pla ce will ca use them to becom e dehydra ted. In com m ercia l stora ge fa cilities, pota toes a re stored a t 90-95% rela tive hum idity (RH), but hom e environm ents a re typica lly not this hum id.
Whe re is the be s t place to s tore potatoe s in the hom e ?
Different pota to va rieties ha ve unique stora ge requirem ents. In the United Sta tes, there ha ve typica lly been three types of pota toes: russets, whites a nd reds. Recently, other unique types of pota toes with yellow, red or blue flesh a nd/or skin ha ve becom e m ore rea dily a va ila ble in stores a nd fa rm er’s m a rkets or to grow in ga rdens. Russets a nd long whites a re used to m a ke ba ked, boiled or fried pota toes. Round white pota toes a re used for either boiling or pota to chips depending on the va riety. Red skinned pota toes a re m ostly used for boiling or sa la ds.
The newer specia lty pota toes com e in m a ny different sizes, sha pes, a nd colors a nd differ enough to be used for boiling, m a shed, ba ked or fried.
Sprouts will a lso grow a t a fa ster ra te when stored a t wa rm er tem pera tures. Sm a ll sprouts ca n ea sily be rem oved before cooking if the tuber is still turgid. If excessive sprouting occurs, tubers m a y becom e fla ccid, ha rd to peel, a nd m a y no longer be a s a ppea ling. Wa rm tem pera tures encoura ge a n increa se in tra nspira tion a nd respira tion, which in turn ca use increa sed wa ter loss a nd potentia lly less firm pota toes.
Since som e va rieties ha ve m ore tha n one culina ry use, you should decide how you intend to use your pota toes before deciding how a nd where to store them . While colder tem pera tures inhibit sprouting, they a lso tend to ca use da rkcolored fried pota toes. If you intend to fry your pota toes, you will wa nt to keep them in a slightly wa rm er pla ce (in other words, not the refrigera tor). This is beca use pota toes tha t a re stored in colder tem pera tures undergo a rea ction tha t converts sta rch into suga rs, which ca uses pota toes to turn a da rk brown color when fried. Da rk colored
French fries a nd pota to chips a re genera lly not considered a s a ppea ling a s golden colored fries a nd chips. This color cha nge will not a ppea r in pota toes tha t a re ba ked or boiled; however, to som e people, a pota to stored in cold conditions will ta ste sweeter once it is boiled or ba ked.
On the other ha nd, tem pera tures tha t a re too cold will ca use your pota toes to turn brown when fried. Freezing tem pera tures ca n ca use pota toes to turn gra y or bla ck.
Light
A pota to tuber a ccum ula tes chlorophyll when exposed to light, which turns the tuber green.
The longer the tuber is exposed to light, the m ore greening will occur. The process will not reverse—the green color will not go a wa y—if you then store the pota to in a da rk pla ce. The green color m a y be una ppea ling, but the color itself does not a ffect the ta ste of the pota to.
However, green pota toes ca n form com pounds ca lled glycoa lka loids tha t develop a long with chlorophyll form a tion. Glycoa lka loids m a y m a ke the pota toes ta ste bitter. In a ddition, glycoa lka loids a re potentia lly toxic if you ea t a lot of green pota toes a t one tim e. If a pota to ha s only sm a ll portions of green, you ca n sa fely rem ove these sections a nd ea t the pota to.
Disca rd pota toes with a high proportion of green skin.
University of Ida ho resea rchers, in coopera tion with College of Southern Ida ho a griculture cla sses, designed a study to look a t the question of where best to store pota toes in the hom e.
Students stored russet pota toes in different loca tions in their hom e, recorded a ir tem pera ture a nd hum idity, a nd wa tched for signs of greening page 2 (ta ble 1). Hom e stora ge loca tions included: 1) a bowl in a kitchen ca binet; 2) a tied, clea r, pla stic produce ba g in a kitchen ca binet; 3) a kitchen countertop; 4) a refrigera tor; 5) a pla stic box in a n unhea ted a rea ; 6) a tied, clea r, pla stic produce ba g in a n unhea ted a rea ; a nd 7) a ca binet under the kitchen sink. Pota toes were a lso stored a t the University of Ida ho Kim berly Pota to
Stora ge Fa cility in a loca tion sim ila r to a com m ercia l stora ge fa cility prior to pa cka ging (45°F,
95%RH). The clea r pla stic produce ba gs used in two of the a bove loca tions were pla stic vegeta ble ba gs a va ila ble in the produce section of m ost grocery stores. Unhea ted a rea s va ried from a n unhea ted room or closet in a hom e, to the ga ra ge, with differing a m ounts of light. ha ve m a ny sm a ll holes cut in the sides to a llow for a ir m ovem ent. Choose a hom e loca tion with high hum idity (such a s a da m p cella r); or eleva te the hum idity of your chosen loca tion by storing the tubers in pla stic ba gs with m a ny holes cut in the sides, a nd/or by pla cing la rge pa ns of wa ter in front of their a ir source. Do not store potatoes in airtight plastic containers.
Overall Recommendations
• Idea l conditions a re ventila ted, cool tem pera tures, high hum idity a nd no light.
• Store a t cool tem pera tures (42-55°F).The wa rm er the tem pera ture, the grea ter the potentia l for sprout developm ent. The cooler the tem pera ture, the grea ter the increa se in suga r concentra tion a nd the da rker the fry color.
Results for the va riety Russet Norkota h from the student’s hom e stora ge study a re shown in ta ble 1. Pota toes stored in a ba g ha d higher hum idity a nd less weight loss when com pa red with pota toes stored in the sa m e loca tion without a ba g. Stora ge a t cooler tem pera tures resulted in da rker fry color (see figure 2 a nd ta ble 1), with tubers stored in the refrigera tor a ccum ula ting the da rkest color. And fina lly, students confirm ed tha t exposure to light resulted in greening.
• Avoid exposure to light to prevent greening.
• Options include:
Purcha se in lim ited qua ntities or on a n “a s needed” ba sis to a void the need for longterm stora ge.
°
Store a wa y from light in a n unhea ted (42-
55°F) room , closet or ca binet in your hom e or ga ra ge.
°
Idea lly, pota toes should be stored in a wellventila ted, cool, da rk, a nd hum id pla ce.
Suggested hom e stora ge loca tions include a n extra refrigera tor set a few degrees higher tha n norm a l tha t you a ccess frequently; or a n unhea ted entra nce, spa re room , a ttic, ba sem ent or ga ra ge insula ted to protect the pota toes from freezing tem pera tures. It is im porta nt for pota toes to be stored in a da rk loca tion or in da rk-colored, perfora ted pla stic ba gs. The ba gs m ust
Store in a perfora ted pla stic ba g to increa se
°hum idity a nd decrea se wa ter loss. Do not tightly sea l the ba g. The goa l is to provide fresh a ir a nd to m inim ize ca rbon dioxide levels a nd disea se developm ent potentia l.
• Do not wa sh ha rvested ga rden pota toes prior to stora ge.
Table 1. The impact of home storage location on the quality of potatoes after 5 weeks
Average Average Weight Treatment humidity loss temperature Green Fry color
(°F) (%) (%)
Cabinet—in a produce bag 68 56 1.6 no light
Cabinet—in a bowl 68 39 2.9 no light
Countertop 68 38 3.0 light yes
Refrigerator no 36 44 2.5 dark no 56 56 1.7 light some 57 67 0.9 light no Under Sink 68 43 2.7 light no UI Storage Facility 45 95 0.6 light Unheated—in a plastic box
Unheated—in a produce bag
page 3
Cabinet Unheated bag bag
Countertop Under sink
Refrigerator UI Potato
Storage
Facility
Figure 2 . Fry color of potatoes stored at home locations for 5 weeks
For more information
• Ida ho Pota to Com m ission:
hopota to.com
About the authors
Lynn Woode ll is an extension support scientist with the Kimberly Research and Extension Center; Nora Ols e n is an associate extension professor with the Twin Falls Research and Extension Center at the University of Idaho; and Jim
Wils on is an associate professor of agriculture at the College of Southern Idaho.
• Pota to Prom otion Boa rd:
lthypota to.com /
• Na tiona l Pota to Council:
tiona lpota tocouncil.org
Issued in furtherance of cooperative extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Charlotte V. Eberlein, Director of University of Idaho Extension, University of Idaho, Moscow, Idaho 83844. The University of Idaho provides equal opportunity in education and employment on the basis of race, color, national origin, religion, sex, sexual orientation, age, disability, or status as a disabled veteran or Vietnam-era veteran, as required by state and federal laws.
March 2 0 0 9
© 2 0 0 9 by the Unive rs ity of Idaho