Gavrila MORAR, Sorin VÂTCĂ
University of Agricultural Sciences and Veterinary Medicine, Faculty of Agriculture, 3-5, Mănăştur Street, 3400, Cluj-Napoca, Romania (contact email: gvmorar@yahoo.com)

Introduction

For industrial processing under the form of chips and French-fries forms the potato is storage in pre processing period for a long period of time at higher temperature (7-10^oC) to avoid the hydrolysis process at the starch in reducing sugars, which can modify the color and the quality of the final product. But at higher temperature physiological processes from tuber are accelerated, the wastage in potato mass appears through germination, respiration and transpiration processes. This wastage must to be monitored in relation with the variety, period of storage (before and after physiological repose) and with the processing period.

Material and methods

The research was carried out in 2001-2002, on five potato varieties: Ostara, Sante, Desiree, Roclas, Romano, on tubers having the same dimension (90-100 g) and physiological age having the same potential (capacity) of germination, same vigor in five repetitions. The mass wastage of potato was determined separately for sprout (presented in this paper) and separately for physiological processes respiration-transpiration, once in each month in another paper. For a good appreciated of the wastage with the view of industrial processing the research was split in two periods: with tubers preserved for processing starting with November-December, right after the normal physiologic repose (80-90 days after harvesting) and for a eventually processing from February, time when the potato was kept in cold conditions at 2-4^oC without sprouting and after was passed at higher temperature preserve for establish the wastage. The wastage through germination was determined thus broken sprouts once one very month, their count and individual and cumulate weighting.

Table 1. Germinating capacity of tubers preserve for processing (sprout numbers/tubers)

Results and discussion

Results obtained regarding germination capacity of the preserve tubers destined industrial processing

The variants sampled from the preservation spot in November were evaluated after one month, time which the potato tubers were kept at the temperature higher then 100C. The first determination was made in December when the potato varieties was get out from vegetative repose excepting made Romano varieties which have a long physiological repose (table 1). The number of sprouts having come out of tubers is smaller (its manifested apical dominancy): one for Ostara, Desiree and Roclas varieties and three at Sante. After removal of this sprout at the next determination the number of sprouts grows significantly up to 5-8 sprouts on each tuber, which signify that once started the sprout germination, in optimal conditions of temperature and aeration, the physiological process from tubers took place in intense rhythm. The period of intense activity take place different for each variety. Some varieties exhausted faster their germination resource (until of the end of the March - Ostara, Sante), although the size of the tubers was relative equal at all varieties. Other varieties which have a higher germinating potential continued to put out sprouts until of the end June.

In the case of the variants extracted from storehouse in February, after one month of preservation in the favorable conditions for germination (higher temperature and aerobe conditions), the debut of the shoots start is massive from the beginning for all the varieties (table 1). Exception was registered at Roclas varieties when at the first determination after one month started just 1-2 sprout/tubers on the others varieties studied the sprout numbers was 5-7-9. The abundant germination on the tubers lasted two months, after which that was lower in May and June. It seems like that the later the germination starts, the stronger it is.

Result obtained regarding the wastage in weight of the tubers because of systematically elimination of the sprouts

In the determination regarding the sprouts mass eliminated monthly systematically beginning with December 2001, we find out that the biggest loses we meet in the first month of preservation at the early varieties (Ostara, Sante) and in February-March-April at late varieties (Desiree, Roclas, Romano) (table 2). Summing the wastage mass values we remarked a big difference between varieties, difference because of shape and consistence of sprout Some varieties have a consistence and mass of the sprouts lowers, the sprouts are delicate or smaller, the total sprouts weight on the tuber being 8-10 g (Ostara, Sante, Romano). The others experimented varieties (Desiree, Roclas) have big, vigor and very consistent sprouts and which they have a total mass eliminated approx 12,7-13,45 g/tubers (table 2).

The same relations between sprouts mass on the tuber and the cultivated varieties is found again in experimental variants put to germination process and evaluated in February-July period. The varieties Ostara, Sante and Romano present lowest mass wastage because of systematical sprout elimination, while as the varieties Desiree and Roclas have big wastage in weight because of same causes: size, thickness and different consistence (table 2).

One simple calculation show as that 8-10 g from 80-100 g mass tubers kept for industrial processing represent 10%, or 10% potato mass wastage destined for processing because only of germination, represent a lot for a processing factory from medium and small enterprises. This wastage can rise at 12-13% in the case of the varieties with vigor sprouts and with a long period by germination.

Conclusion

The germinate capacity of the varieties are different, the earlier varieties having the germinating potential reduced.

When germination is produced later then that it is more vigorous.

At the earlier varieties the biggest wastage is registered in the first month by preserve, fact that implies a earlier processing of them.

The mass wastage of the tubers is differentiating by varieties. Some varieties form thin sprout (Ostara), shorter (Sante), while other varieties (Desiree, Roclas) have bulk and consistent sprouts.

The mass wastage of the tubers preserved for processing can rise only because of successive germination during preserving period at 10-13%.

References

1. Beukema, H.P., D.E. van der Zaag,1990, Introduction to potato production, Pudoc Wageningen, Nederlands

2. Mureşan S., V. Donescu, Teodora Panea, 1985, Cercetări privind efectul sării de sodiu a hidrazei maleice asupra creşterii colţilor şi a reducerii pierderilor prin păstrare la cartof. Lucrări Ştiinţifice (Anale) ICPC Braşov, vol XIV, p. 187

3. Donescu V., 1996, Comportarea la păstrare a soiurilor şi liniilor noi de cartof la ICPC Braşov, Lucrări Ştiinţifice (Anale), vol XXIII, p. 37-43