carbon dioxide concentration in commercial potato storages and its effect on quality of tubers for...

1990) 121

CARBON DIOXIDE C O N C E N T R A T I O N IN C O M M E R C I A L POTATO STORAGES AND ITS EFFECT ON Q U A L I T Y

OF TUBERS FOR PROCESSING

G. Mazza and AJ. Siemens 1

Abstract

Commercial potato storage bins were monitored over two storage seasons for carbon dioxide content of the atmosphere and for reducing sugars, sucrose and chip color of the tubers. Concentrations of carbon dioxide in the storages tested ranged from 0.06 to 3.2 %. Values higher than 1% were found in about 50% of the storages in 1986-87 but in none in 1987-88. The highest carbon dioxide levels occurred primarily during the suberization period and during application of the sprout inhibitor, CIPC. Reducing sugars and sucrose contents ranged from 0.06 to 0.85% and from 0.2 to 3.1 mg/g of fresh tuber, respectively. Increases of reducing sugars and sucrose, and darkening of the chips made from the tubers generally occurred immediately after rises in carbon dioxide concentration. In most cases, the detrimental effect of high levels of carbon dioxide on the color of the fried products was temporary.

Compend io

Durante dos temporadas de almacenamiento de papa se efectu6 un estudio de dep6sitos comerciales, para hacer un seguimiento del conteni- do de di6xido de carbono en la atm6sfera y de azdcares reductores y sacarosa en los tub6rculos, as~ como de las variaciones en el color de las frituras a la inglesa de los mismos. Las concentraciones de didxido de carbono en los almacenes estudiados variaron de 0.06 a 3.2%. En 1986-87, se encon- traron valores mayores de 1% en aproximadamente 50% de los almacenes, pero en ninguno en 1987-88. Los niveles m~s altos de di6xido de carbono se presentaron principalmente durante el periodo de suberificacidn y durante la aplicaci6n del inhibidor del brotamiento, CIPC. Los conteni- dos de azdcares reductores y de sacarosa variaron de 0.06, a 0.85 % y de 0.2 a 3.1 mg/g de tub6rculo fresco, respectivamente. Inmediatamente despu~s del aumento en la concentraci6n de di6xido de carbono se regis- traron incrementos en azdcares reductores y en sacarosa, y se observ6 el obscurecimiento de las papas fritas a la inglesa. En la mayorfa de los ca-

1Research Scientist and Research Associate, Food Research Laboratory, Agriculture Cana- da, Research Station, Morden, MB, R0G 1J0, Canada. Accepted for publication September 29, 1989. ADDITONAL KEY WORDS: Carbon dioxide concentration, potato storage, potato quality, sucrose, reducing sugars, dry matter, storage temperature.

122 AMERICAN POTATO JOURNAL (Vol. 67

sos, el efecto negativo de los.altos niveles de di6xido de carbono sobre el color de las frituras producidas, fue temporal.

Introduction

In recent years there has been increased interest in the influence of carbon dioxide (CO2) on storability and quality of potatoes for processing. As a result, carbon dioxide has been correlated with or shown to influence disease incidence (6, 10, 18), sugar accumulation (20, 21), chip color (15), malate content (15) and greening of potatoes (11).

Factors affecting production of carbon dioxide by potato tubers of different cultivars at differences stages of maturity and under various storage conditions have also been studied (13, 14). The results of these efforts are, however, often contradictory and most of the determinations have been carried out in laboratories where disturbance of the water balance and changes in the rate of respiration of the tubers are often unavoidable.

This study was carried out to determine the concentration of carbon dioxide in commercial potato bins and to attempt to relate its effect on color of potato chips, sucrose and reducing sugars, and dry matter content of Russet Burbank, Norchip, Kennebec and Monona potatoes.

Materials and Methods

During the 1986-87 storage season, 18 commercial potato storage bins, located on farms in southern Manitoba, each containing 500 to 2500 tonnes of Russet Burbank (12 bins), Norchip (4 bins), Kennebec (1 bin) and Mo- nona (1 bin) potatoes were monitered for carbon dioxide content of the storage atmosphere and for quality of the tubers as expressed by content of sucrose and reducing sugars and color of potato chips. During the 1987-88 season, 15 bins of Russet Burbank, 6 bins of Norchip and 1 bin of Mono- na potatoes were sampled. All bins were equipped with a proportioning air handling and distribution system consisting of a main fan, a plenum chamber, a main duct, lateral or distribution ducts, a damper or door ar- rangement, and an exhaust fan(s). In all cases, the bins were either par- tially or completely controlled manually by experienced operators. In 1986, sampling was started after the suberization period when the temperature was lowered to about 10~ and relative humidity was about 90%. In 1987, sampling began at harvest time and all bins were monitored from the time they were filled to the time they were emptied. During the 1-2 week suberization period, pile temperatures ranged from 13-18~ and relative humid- ities ranged from 85-95%. All potatoes were sprout inhibited with CIPC (isopropyl-N(3-chlorophenyl)-carbamate, active ingredient) applied as an aerosol in December-January.

Air samples were taken from each storage bin every 25-30 days during the n.ormal storage period and every 1-2 days during the suberization and sprout inhibition periods. Air samples were taken on top of potato piles,

1990) MAZZA AND SIEMENS: CARBON DIOXIDE C O N C E N T R A T I O N 123

at 2-4 locations using 130 ml screw cap septum bottles evacuated prior to sampling of the air in the storage bin. The evacuated bottles were opened for 1-2 min. at the predetermined location in the bin and then resealed for transport to the laboratory where a sub-sample of air was taken from the sealed bottle with a gas syringe and analyzed for concentration of carbon dioxide by the infrared method of Clegg, et al. (4). All air samples were taken from the top of the potato pile when the ventilation system of the storage was in operation, and in all cases, the fans were on for at least 20 min. pri- or to sampling.

With each sample of air, a corresponding sample of tubers was also taken and analyzed for contents of dry matter, sucrose and reducing sugars and for chip color. Temperature and relative humidity of the storage were also recorded. The dry matter content of the tubers was calculated from specific gravity values, obtained by weighing samples of potatoes in air and immersed in water, using the following equation proposed by Sim- monds (16):

Dry matter (% F.W.B.)=2.2+49.1 U, where U=(5G-5) /G and G= specific gravity

The sucrose and reducing sugars were determined by the anthrone colorimeter method of Sowokinos (17), and by the 3, 5-dinitro salicylate method of Ross, (12), respectively.

Potato chips were obtained by slicing the peeled tubers into 1 mm thick slices with a Hobart slicer (The Hobart Manufacturing Company, Toron- to, Ont.). The slices were rinsed in cool water, the excess water being re- moved by shaking, and then fried in hydrogenated vegetable oil at 190~ in a thermostatically controlled Garland deep fat fryer. The end point of frying was determined by cessation of bubbling.

Chip color was measured with a Model E-5F Agtron color meter in the X1 scale. This allowed readings to be taken in the 0-100% green to infrared reflectance ratio mode. Values of fifty-two units or more represent- ed acceptable chip colors, and thirty or more units an acceptable French fry color. Agtron readings can be converted to United States Department of Agriculture color units (19) by multiplying the Agtron units by -0.09 and adding 5.16 (8).

Data were analyzed using descriptive statistics and linear correlation packages available from SAS (Cary, NC). The results must be interpreted cautiously because the data were collected from commercial storages in which the potatoes were stored and managed under a wide range of conditions.

Results and Discussion

Changes in concentration of carbon dioxide and temperature of the atmosphere of a commercial Russet Burbank potato bin, together with chip


color and contents of sucrose, reducing sugars and dry matter of tubers are shown in Fig. 1. The patterns for chip color, sucrose, reducing sugars and dry matter are similar to those reported by Mazza and coworkers (7, 8) for potatoes grown and stored in Alberta, and show that throughout the

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Storage Period

FIG 1. Changes in concentration of carbon dioxide and air temperature of a commercial storage bin atmosphere and associated changes in chip color, reducing sugars, sucrose and dry matter of Russet Burbank potatoes during the 1987-88 storage season.

1990) MAZZA AND SIEMENS: CARBON DIOXIDE CONCENTRATION 125

storage period there were shifts in these quality attributes of potatoes. The plot of concentration of carbon dioxide in the atmosphere of the storage bins vs. storage time displayed two major peaks coinciding with the suberization or wound healing period and the sprout inhibition period. The suberization or wound healing period, which corresponds to the first 1-2 weeks after harvest, is characterized by a high rate of respiration (14). There- fore, high concentrations of carbon dioxide in the storage atmosphere were expected. The large increase in carbon dioxide concentration at the time of sprout inhibition, however, was not expected as Boe, et al. (1) reported that Russet Burbank potatoes treated with CIPC dust showed less respiration than the control. The substantial increase in carbon dioxide observed in this study was believed to be caused by the reduction of fresh air intake, for a period of 8-48 hours, depending on the storage management practices, during the application of CIPC as aerosol. A third CO2 peak was noted in May and June. This peak is probably due to reduced air intake as the outside temperature increased. As senescence approached, (June and July) CO2 levels continued to climb.

Throughout the two storage seasons, the concentration of carbon dioxide in the storage bins was well above the ambient level of 0.03 %, and varied considerably between bins and time of sampling (Tables 1 and 2). The highest concentration of carbon dioxide was 3.2 + 0.02 % and this was measured in a storage bin containing 2500 tonnes of potatoes which re- quired over 3 hours to apply the sprout inhibitor. In the 1986-87 season, the mean carbon dioxide level during the sprout inhibition process was 1.11 _ 0.74%, and the relatively high carbon dioxide levels during this period lasted from 2 to 5 days. During normal storage conditions and after sprout inhibition, carbon dioxide content remained in the range of 0.13 to 0.46% (Table 1). During the suberization or wound healing period in 1987-88, which lasted from 8 to 14 days, the carbon dioxide concentration of the storage atmosphere in the storage bins ranged from 0.09 + 0.01 to 0.63 -+ 0.09% (Table 2). After suberization, the carbon dioxide level in the 22 storage bins tested in 1987-88 averaged 0.18 + 0.10%. This was lower than the value of 0.23 -+ 0.15% measured in the 1986-87 season, and significantly lower than the values reported in the literature (13). The levels of carbon dioxide during the sprout inhibition period were also lower in 1987-88 than in 1986- 87, and the reduction reflected changes in storage management practices, specifically a shorter time without intake of fresh air after the application of the sprout inhibitor. Generally, storage bins filled with Norchip potatoes had lower carbon dioxide levels than those filled with Russet Burbank potatoes, and this was probably due to differences in maturity and degree of bruising of the potatoes at harvest, as well as differences in size and operation of the storage bins, especially lower storage temperature and larger storage bins for Russet Burbank potatoes. Because only one storage bin of Kennebec and two storage bins of Monona potatoes were monitored over


TABLE 1 . - Carbon dioxide concentration in the storage atmosphere of commercial potato storages in Manitoba during the 1986-87 season.

Bin Carbon dioxide concentrations (%)

Number AS 1 SI 2 ASP SEN 4

1 RB 5 0 . 1 5 _ + 0 . 0 1 6 1.24_+0.10 0.19_+0.05 -- 2 RB 0.18_+0.02 0.80_+0.18 0.18_+0.03 -- 3 RB 0.21_+0.05 0.95-+0.09 0.24-+0.16 -- 4 RB 0.41-+0.08 -- 0.22+0.11 -- 5 RB 0.27_+0.15 0.40_+0.05 0.21-+0.08 0.19_+0.01 6 RB 0.46-+0.37 1.20_+0.10 0.19_+0.07 -- 7 RB 0.19_+0.13 3.20_+0.02 0.23_+0.12 0.12_+0.03 8 RB 0.29_+0.19 1 . 7 1 _ + 0 . 0 6 0.18_+0.07 -- 9 RB 0.25_+0.13 0.57_+0.12 0.19_+0.06 0.19_+0.06

10 RB 0.23_+0.07 0.40_+0.08 0.17_+0.08 -- 11 RB 0.26_+0.10 0.82_+0.07 0.23_+0.09 -- 12 RB 0.25_+0.15 0.72_+0.16 0.23_+0.11 -- 13 N 0.16_+0.01 0.31_+0.03 0.16_+0.03 -- 14 N 0.13_+0.05 0.23_+0.03 0.15+0.04 0.16-+0.02 15 N 0.18-+0.11 2.05_+0.13 0.17_+0.07 0.25_+0.02 16 N 0.18_+0.09 1.09_+0.08 0.16+_0.02 -- 17 M 0.17_+0.08 1 . 2 2 _ + 0 . 0 1 0.19___0.06 -- 18 K 0.16-+0.10 1.32---0.06 0.18_+0.06 --

Mean 0.23_+0.15 1.11_+0.74 0.19_+0.08 0.18_+0.04

IAfter suberization period and before initiation of sprout inhibition process. 2Peak CO2 levels obtained during sprout inhibition process. 3After sprout inhibition and when normal ventilation practices resumed. ~Time when senescence detected by an increase in sucrose rating. 5RB, Russet Burbank; N, Norchip; M, Monona, K, Kennebec. 6Standard deviation, n~>3.

the two seasons o f the s tudy, no r e l i a b l e c o n c l u s i o n can be d r a w n a b o u t these two cultivars; however, the l imi ted c a r b o n d ioxide d a t a collected suggest t ha t these two c h i p p i n g p o t a t o cu l t iva r s b e h a v e d m o r e l ike N o r c h i p t h a n R u s s e t B u r b a n k p o t a t o e s (Tables 1 a n d 2).

Sucrose , r e d u c i n g sugars a n d d r y m a t t e r con t en t s o f po ta toes , as well as co lo r o f chips m a d e f r o m t u b e r s t a k e n f rom each s to rage b i n at the t i m e a n d l o c a t i o n o f a i r s a m p l i n g , v a r i e d ove r the s to rage t ime , as i l l u s t r a t ed in F ig . 1, a n d b e t w e e n s to rage b ins , seasons a n d cu l t iva rs (Tables 3 a n d 4). Gene ra l l y , con t en t s o f sucrose a n d r e d u c i n g sugars in p o t a t o e s t e n d e d to i n c r e a s e 10-20 days a f te r f ogg ing o f b in s w i th C I P C , a n d co lor o f ch ips t e n d e d to get d a r k e r a t t ha t t ime . C h u b e y (3) h a d p r e v i o u s l y shown tha t sucrose i nc reased m a r k e d l y in r e sponse to C I P C t r e a t m e n t . However , du r - ing this s torage per iod, all Norchip , M o n o n a and K e n n e b e c pota toes y ie lded ch ips w i th co lor va lues g r e a t e r t h a n 52 A g t r o n uni t s , a n d thus were c o m - m e r c i a l l y ' a c c e p t a b l e . By c o m p a r i s o n , less t h a n 30% of the 25 s to rage b i n s


TABLE 2 . - - Carbon dioxide concentration in the storage atmosphere of commercial potato storages in Manitoba during the 1987-88 season.

Bin Carbon dioxide concentrat ions (%)

N u m b e r & Cul t ivar PS 1 S 2 AS 3 SI ~ ASI 5 SEN 6

1 RB 7 0.20+0.008 0.27+0.08 0.10+0.02 0.44_+0.03 0.20+0.05 -- 2 R B 0.14-+0.00 0.21-+0.00 0.16+0.02 0.40-+0.12 0.17-+0.02 -- 3 RB 0.20___0.00 0.09_+0.00 0.13_+0.05 N/A 0.21_+0.00 -- 4 R B 0.23_+0.00 0.35+_0.05 0.18_+0.18 0.98_+0.02 0.20_+0.10 0.22_+0.01 5 RB 0.18-+0.02 0.44_+0.05 0.23_+0.09 0.46_+0.01 0.19_+0.11 0.42_+0.25 6 R B - - -- 0.08+0.01 0.41_+0.02 0.18___0.07 -- 7 RB 0.40-+0.21 0.40-+0.09 0.13+0.06 0.50___0.01 0.22-+0.06 -- 8 RB 0.12-+0.02 0.50-+0.01 0.18-+0.07 0.70_+0.00 0.21_+0.00 -- 9 RB 0.26+0.03 0.42-+0.05 0.14-+0.03 0.37_+0.02 0.18_+0.00 --

10 RB 0.08_+0.01 0.09_+0.02 0.23_+0.02 0.37_+0.02 0.47_+0.20 0.47-+0.39 l l R B 0.17-+0.01 0.63-+0.09 0.26_+0.06 0.51+0.07 0.20_+0.07 1 2 R B -- 0.21_+0.02 0.20_+0.08 0.33_+0.00 0.19_+0.01 -- 1 3 R B -- 0.15+0.02 0.21_+0.06 0.35_+0.00 0.20+_0.02 0.26-+0.00 1 4 R B -- 0.20-+0.01 0.21_+0.08 0.38_+0.00 0.18_+0.05 -- 15 RB 0.10_+0.02 0.50+0.10 0.29_+0.17 -- -- -- 16 N 0.13___0.01 0.24-+0.05 0.12-+0.03 -- -- -- 1 7 N 0.20-+0.09 0.31_+0.11 0.12_+0.02 0.20_+0.00 0.14• -- 18 N -- 0.25_+0.03 0.13-+0.03 0.23+0.01 0.17_+0.04 -- 1 9 N -- -- 0.14_+0.00 0.14_+0.00 0.17_+0.06 0.15_+0.05 20 N -- -- 0 .18+0.02 0.36_+0.02 0.19+0.09 0.32_+0.02 21 N 0.35_+0.09 0.47-+0.04 0.14+0.02 -- -- -- 2 2 M -- -- 0.17_+0.01 0.59_+0.10 0.25_+0.06 0.27_+0.06

M e a n 0.20_+0.10 0.33_+0.16 0.18_+0.10 0.44-+0.19 0.21-+0.11 0.32-+0.24

1Air samples taken immediately after filling and closing of b in and before peak CO2 levels obtained dur ing the suberization period. 2Peak levels of CO2 obtained dur ing suberizat ion period. 3After suberizat ion period and before init iat ion of sprout inhibi t ion process. *Peak CO2 levels obtained dur ing sprout inhibi t ion process. 5After sprout inhibi t ion and when normal ventilation practices resumed. 6Time when senescence detected by an increase in sucrose rating. 7RB, Russet Burbank; N, Norchip; M, Monona . 8Standard deviation, n~>3.

o f R u s s e t B u r b a n k p o t a t o e s a s s a y e d y i e l d e d a c c e p t a b l e F r e n c h f r i e s a n d

n o n e o f t h e s e p o t a t o e s y i e l d e d a c c e p t a b l e p o t a t o c h i p s . T h e d i f f e r e n c e i n

c h i p c o l o r b e t w e e n R u s s e t B u r b a n k a n d t h e c h i p p i n g p o t a t o c u l t i v a r s ( N o r -

ch ip , K e n n e b e c a n d M o n o n a ) is c o n s i s t e n t w i t h t h e h i g h e r levels o f r e d u c i n g

s u g a r s i n R u s s e t B u r b a n k p o t a t o e s ( T a b l e s 3 a n d 4) a n d a g r e e s w i t h p r e v i -

o u s s t u d i e s w h i c h h a v e s h o w n b e t t e r p r o c e s s i n g q u a l i t y o f p o t a t o e s c o n -

t a i n i n g low leve ls o f r e d u c i n g s u g a r s (5, 8, 9, 17). S u c r o s e level i n t h e t u b e r s

i n c r e a s e d 10-14 d a y s a f t e r a p p l i c a t i o n o f C I P C b y 5 - 1 0 0 % i n 5 o f t h e 8 s to r -


TABLE 3.--Sucrose, reducing sugars and dry matter content and chip color of commercially stored potatoes 2 Weeks after sprout inhibition in the 1986-87 season.

Bin Number & Sucrose Reducing sugars Dry matter Chip color Cultivar (mg/g) (%) (%) (Agtron units) 3

1 RB 1 0 .93- - -0 .072 0.22_+0.01 22.3+0.7 36.0_+3.1 2 RB 0 . 7 1 _ + 0 . 3 9 0.26_+0.06 21.9+0.7 33.9_+2.9 3 RB 0.55_+0.13 0.57_+0.09 24.5_+0.7 23.8_+4.6 4 RB . . . . 5 RB 1.43+_0.07 0.58-+0.03 22.9_+0.2 19.7_+4.1 6 RB 1.03+_0.10 0.61-+0.06 22.9-+0.7 16.7_+2.9 7 RB 1.86_+0.46 0.63+0.12 22.3+1.0 23.2_+1.4 8 RB 2.25+0.08 0.50_+0.04 24.4_+0.4 19.5_+2.5 9 RB 0.95_+0.33 0.44_+0.09 22.6_+0.8 30.0_+0.8

10 RB 0 . 8 4 _ + 0 . 0 5 0.46_+0.22 24.0_+1.0 26.4_+3.3 11 RB 1.22_+0.04 0.45_+0.06 23.1+0.6 27.1-+5.5 12 RB 0.83+0.18 0.39-+0.06 23.6-+1.2 28.4-+5.8 13 N 0.95+_0.12 0.10_+0.01 22.1_+0.5 56.9+5.8 14 N 1.58_+0.32 0.10-+0.02 22.1_+0.4 53.8_+6.3 15 N 1.53_+0.01 0.09_+0.01 22.8_+0.4 58.3___1.2 16 N 2.38_+0.15 0.09_+0.15 22.8_+0.6 60.1_+2.2 17 M 1.25_+0.18 0.09_+0.01 21.2_+0.3 56.2_+1.0 18 K 0.59_+0.20 0.12_+0.02 23.2_+0.7 55.3_+5.6 Mean 1.25-+0.58 0.38-+0.22 22.8+1.0 35.7+_16.4 1RB, Russet Burbank; N, Norchip; M, Monona, K, Kennebec. 2Standard deviation, n~>3. 3Higher Agtron readings indicate lighter chip color.

age bins containing Norchip potatoes and in only 10 of the 24 storage bins containing Russet Burbank potatoes. This agrees with earlier observations (8) and suggests distinct cult ivar differences with regard to accumul t ion of sucrose in the tubers following storage stresses such as increased carbon dioxide levels resulting from the application of sprout inhibitor and reduction of fresh air intake dur ing this operat ion. T h e da ta presented in Tables 3 and 4 also reveal that growing/storage season had little effect on chip color and sucrose, reducing sugars and dry ma t t e r levels in the tubers which had been in storage for 3-4 months . Storage bin m a n a g e m e n t , especially t im- ing and volume of fresh air intake in the bin seem much more impor tan t .

Significant correlation coefficients between carbon dioxide of storage a tmosphere , chip color, sucrose, reduc ing sugars and dry ma t t e r contents of tubers and storage tempera ture for the 1986-87 and 1987-88 storage seasons are given in Tables 5 and 6, respectively. Relatively low but highly significant coefficients with ca rbon dioxide were obta ined for chip color, sucrose, reducing sugars and storage t e m p e r a t u r e of Russet B u r b a n k and


TABLE 4.--Sucrose, reducing sugars and dry matter content and chip color of commercially stored potatoes 2 weeks after sprout inhibition in the 1987-88 season.

Bin Number & Sucrose Reducing sugars Dry matter Chip color Cultivar (rag/g) (%) (%) (Agtron units) 3

1 RB 1 0 . 4 1 + _ 0 . 0 1 2 0.48+_0.09 23.4+_1.0 31.9_+6.9 2 RB 0.73+_0.26 0.34_+0.04 23.8+_0.3 34.1_+5.8 3 RB . . . . 4 RB 0.77+_0.18 0.30+_0.06 24.4+_0.6 47.8+_10.8 5 RB 0.83_+0.17 0.52+_0.09 23.2_+0.4 21.8+_5.0 6 RB 0.80+_0.40 0.39+_0.02 23.3___1.1 28.5+_3.3 7 RB 1.16+_0.27 0.59+0.27 22.4+_0.4 15.4+_0.6 8 RB 0.74+_0.20 0.39+_0.03 21.9+_1.5 34.3_+1.5 9 RB 1.07_+0.02 0.59+_0.05 24.0+_0.5 18.7+_3.7

10 RB 0.74+_0.36 0.56+_0.04 23.2+_0.8 21.1+_2.3 11 RB 1.95+_0.50 0.68+_0.02 24.6+_0.4 19.2_+2.1 12 RB 1.14_+0.65 0.46_+0.02 23.8_+0.5 27.7_+1.4 13 RB 1.68+0.59 0.72+_0.20 23.8+_1.2 16.6+_8.0 14 RB 1.30+_0.00 0.42+_0.00 23.5+_0.0 28.1+_1.0 15 RB -- -- -- " -- 16 N . . . . 17 N 2.34+_0.66 -- -- -- 18 N 1.46-+0.22 0.17-+0.02 22.1_+0.6 62.2+_1.3 19 N 1.45_+0.10 0.15+_0.00 22.0+_0.5 59.0+_7.8 20 N 1.68_+0.46 0.13+_0.00 20.9+_0.4 64.1_+2.9 21N . . . . 22 M 0.79+_0.11 0.79+_0.11 20.3+_0.4 68.4+_3.2 Mean 1.13+_0.58 0.41+_0.18 22.7_+1.4 34.5+_17.4

1RB, Russet Burbank; N, Norchip; M, Monona. 2Standard deviation, n>~3. 3Higher Agtron readings indicate lighter chip color.

N o r c h i p po ta toes s to red in 1987-88. I n 1986-87, however , on ly sucrose a n d s to rage t e m p e r a t u r e o f b o t h R u s s e t B u r b a n k a n d N o r c h i p p o t a t o e s were s ign i f i can t ly c o r r e l a t e d w i th c a r b o n d iox ide . I n b o t h seasons , c o r r e l a t i o n s o f c a r b o n d iox ide a n d s to rage t e m p e r a t u r e wi th qua l i t y p a r a m e t e r s of N o r - chip tubers were genera l ly h igher t han those of Russe t Burbank . T h e posit ive s igns o f the coeff ic ients i nd ica t e t ha t i n c r e a s e d levels o f c a r b o n d i o x i d e cor- r e s p o n d to d a r k e r ch ip co lo r a n d i n c r e a s e d c o n c e n t r a t i o n o f sucrose a n d r e d u c i n g sugars in the tubers . T h e co r r e l a t i on coeff ic ients b e t w e e n c a r b o n d i o x i d e a n d s to rage t e m p e r a t u r e was gene ra l l y low, b u t a lways h i g h l y sig- n i f i can t a n d posi t ive . T h i s ag rees w i t h the resul ts o f n u m e r o u s s tud ies on r e s p i r a t i o n o f p o t a t o e s w h i c h have s h o w n tha t in the r a n g e o f 0 - 2 0 ~ in- c reases in s to rage t e m p e r a t u r e cause inc reases in the r a t e o f r e s p i r a t i o n w h i c h in t u r n causes i n c r e a s e in t e m p e r a t u r e (2, 14). A c c o r d i n g to B u r t o n

130 AMERICAN P O T A T O JOURNAL ( V o l . 67

TABLE 5.--Significant correlation coefficients among storage and quality parameters of Russet Burbank, Norchip, Kennebec and Monona potatoes

stored commercially in Manitoba, Canada in the 1986-87 season.

Quality/storage Chip Reducing Cultivar parameters color Sucrose sugars Dry matter

Russet Burbank Carbon dioxide -0.118 *a 0.216"*** - - Chip color 0.169" -0.691"*** -0.291"*** Sucrose - - Reducing sugars 0 .403 ' * * * Dry matter

Norchip Carbon dioxide - 0 .460 ' * * * - - Chip color - -0.565**** 0.303* Sucrose - - Reducing sugars -0.307" * * Dry matter

All cultivars Carbon dioxide - 0.237 * * * * - - Chip color 0.206**** -0.884"*** -0.437**** Sucrose -0.217"* - Reducing sugars 0.503" * * * Dry matter

Storage temperature

0.113" 0.523**** 0.126"*

-0.390**** -0.242****

0.212"* -0.239** 0.360**** 0.404****

0.110"* 0.514"*** 0.212"***

-0.509**** -0.328****

a'p_<0.10; **p--<0.05; ***p--<0.01; ****p--<0.001.

TABLE 6 . - -S ign i f i c an t correlation coefficients among storage and quality parameters of Russet Burbank, Norchip, Kennebec and Monona potatoes

stored commercially in Manitoba, Canada in the 1987-88 season.

Quality/storage Chip Reducing Storage Cultivar parameters color Sucrose sugars Dry matter temperature

Russet Carbon dioxide -0.170 ****a 0.136 '*** 0.255**** - 0.195"*** Burbank Chip color 0 .220****-0.762**** 0.228**** 0.439****

Sucrose -0.161"** 0.252**** 0.313"*** Reducing sugars - -0.176"*** Dry matter -0.131 * *

Norchip Carbon dioxide -0.187" 0.385**** 0.172" - 0212"* Chip color -0.335**** -0.405**** 0.235* - Sucrose 0.373**** -0.300*** 0.298*** Reducing sugars - -0.348" * * * Dry matter

All Carbon dioxide -0.197"** - 0.272**** - 0.157"*** cultivars Chip color 0.306**** -0.845'*** -0.388**** 0.391"***

Sucrose -0.257**** ~ 0.364**** Reducing sugars 0 .349 ' * * * -0.257" * * * Dry matter

a'p_<0.10; **p_0 .05 ; ***p_<0.01; ****p--<0.001.


(2), for every g ram of carbon dioxide produced in respiration about 10 kJ of energy are released in the form of heat.

The results of this study have indicated: (a) carbon dioxide concentrations in commercial potato storage bins vary considerably between storage bins and with time of sampling; (b) cultivar, storage season and storage managemen t affect concentrat ion of carbon dioxide in storage bins; (c) chip color and contents of sucrose and reducing sugars of tubers are affected by concentration of the carbon dioxide of storage atmosphere, but the affect is only temporary.

A c k n o w l e d g m e n t s

The authors thank Jeff Friesen for his technical assistance, members of the Keystone Vegetable Producers Association for their cooperation and the Canada-Mani toba Agri-Food Program for the financial support of AJS.

Literature Cited

1. Boe, A.A., G.W. Woodbury and T.S. Lee. 1974. Respiration studies on Russet Bur- bank potato tubers: effects of storage temperature and chemical treatments. Am Potato J 51:355-360.

2. Burton, W.G. 1978. The physics and physiology of storage. In: The Potato Crop, P.M. Harris (Ed.), Chap. 14, Chapman and Hall Ltd., London, England.

3. Chubey, B.B. 1981. Sucrose rating proving a good measure at harvest. Chipper/snacker, February, pp. 33-34.

4. Clegg, M.D., C.Y. Sullivan and J.D. Eastman. 1978. A sensitive technique for the rapid measurement of carbon dioxide concentrations. Plant Physiol 62:924-926.

5. Iritani, W.M. and L.D. Weller. 1976. Relationship of specific gravity to sugar accumulation in stored Norgold and Russet Burbank potatoes. Am Potato J 53:57-65.

6. Lund, B.B. and G.M. Wyatt. 1972. The effect of carbon dioxide concentration on bacterial soft rot of potatoes. I. King Edward potatoes inoculated with Erwinia carotovora vat. atroseptica. Potato Res 15:174-179.

7. Mazza, G. 1983. Correlations between quality parameters of potatoes during growth and long-term storage. Am PotatoJ 60:145-159.

8. Mazza, G., J. Hung and M.J. Dench. 1983. Processing/nutritional quality changes in potato tubers during growth and long term storage. Can Inst Food Sci Technol J 16:39-44.

9. Miller, R.A., J.D. Harrington and D.G. Kuhn. 1975. Effect of variety and harvest date on tuber sugars and chip color. Am Potato J 52:379-386.

10. Nielsen, L.M. 1968. Accumulation of respiratory CO2 around potato tubers in rela- tion to bacterial soft rot. Am Potato J 45:174-181.

11. Poapst, P.A. and F.R. Forsyth. 1974. The role of internally produced carbon dioxide in the prevention of greening in potato tubers. Acta Hortic 1:277-290.

12. Ross, A.G. 1975. Dinitrophenol method for reducing sugars. In: Potato Processing, 3rd edition, W.F. Talburt and O. Smith (Eds.). p. 696. AVI Publishing Company, Inc., Westport, CT.

t3. Schaper, L.A. andJ.L. Varns. 1978. Carbon dioxide accumulation and flushing in potato storage bins. Am Potato J 55:1-14.


14. Schippers, RA. 1977. The rate of respiration of potato tubers during storage. I. Re- view of literature. Potato t~es 20:173-180.

15. Sherman, M. and E. Ewing. 1983. Effects of temperature and low oxygen atmospheres on respiration, chip color, sugars and malate of stored potatoes. J Amer Soc Hort Sci 108:129-133.

16. Simmonds, N.W. 1977. Relations between specific gravity, dry matter content and starch content of potatoes. Potato Res 20:137-140.

17. Sowokinos, J.R. 1978. Relationshipofharvest sucrose content to processing maturity and storage life of potatoes. Am Potato J 55:333-345.

18. Tabak, H.H. and W.B. Cooke. 1968. The effects of gaseous environments on the growth and metabolism of fungi. Bot Rev 34:126-252.

19. USDA Processed Products Standardization and Inspection Branch. 1972. United States Standards for Grades of Frozen French Fried Potatoes. Third Issue, Febru- ary 8.

20. Workman, M. andJ. Twomey. 1969. The influence of storage atmosphere and temperature on the physiology and performance of Russet Burbank seed potatoes. J Am Soc Hort Sci 94:260-263.

21. Workman, M. andJ. Twomey. 1970. The influence of storage on the physiology and productivity of Kennebec seed potatoes. Am Potato J 47:372-378.

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