Page 10 



BETTER FRUIT 



December, 1920 



Ripening and Storing of Bartlett Pears 



By J. R. Magness, Plant Physiologist, Horticultural and Pomological Investigations, 

 U. S. Bureau of Plant Industry 



PERHAPS there is no major fruit crop 

 grown in the Pacific Coast States 

 that offers greater difficulty in the 

 handling and marketing than does the 

 Bartlett pear. This is due to its being 

 a highly perishable fruit, to the fact 

 that there is a wide variation in the 

 keeping quality of fruit from various 

 sections, and to a misunderstanding on 

 the part of many handlers of the effect 

 of such factors as time of picking, tem- 

 perature at which stored, etc., on the 

 keeping quality and dessert quality of 

 the ripened fruit. 



During the summer of 1919 a series 

 of studies was made to determine the 

 changes taking place in Bartlett pears 

 as they devolop on the tree and as they 

 ripen after being picked. The effect of 

 storing the fruit at different temper- 

 atures was also studied. Fruit was se- 

 cured from typical orchards of the Sac- 

 ramento River district, and from Suisun, 

 Cal., from the Medford district, Oregon, 

 and from Selah in the Yakima Valley, 

 Washington. Pickings were made three 

 weeks before the commercial season 

 opened in each of these districts and 

 at intervals thereafter until after the 

 last commercial fruit had been removed 

 from the trees. 



Chemical analyses for sugar, acid, 

 starch and dry matter were made when 

 fruit of each picking was removed from 

 the tree and again when this same fruit 

 was full yellow ripe and in prime eat- 

 ing condition. The fruit was analyzed 

 after being held in storage at 70, 45 and 

 30 degrees F. 



It was found that there is a progres- 

 sive increase in the sugar content of 

 the fruit from early summer until after 

 the end of the commercial season. Be- 

 tween the time of the first and of the 

 last commercial pickings the sugar in- 

 creased from an average of about 6 per 

 cent to an average of about 8 per cent 

 of the weight of the fruit. Between the 

 time of picking and the time the pears 

 are full yellow ripe there is a further 

 increase in sugar due apparently to the 

 change of starch and similar materials 

 into sugar. Early picked pears, which 

 contained about 6 per cent of sugar 

 when first taken from the trees, con- 

 tained about 8 per cent when soft ripe, 

 and pears picked toward the end of 

 the picking season and containing about 

 8 per cent sugar when removed from 

 the tree contained about 10 per cent 

 when full yellow ripe. It is thus ap- 

 parent that to obtain the fruit richest 

 in sugar it should be left on the tree as 

 long as possible. 



The total amount of sugar found in 

 the fruit at the various stages of devel- 

 opment was very nearly the same in 

 pears from the different regions studied. 

 This did not hold true for acids, how- 

 ever, as a considerably greater amount 

 of acid was found in the northern 

 grown fruit. Since acid and sugar are 

 equally important factors in determin- 

 ing the flavor of the fruit, the greater 

 amount of acid in the northern fruit 

 probably accounts for the idea preva- 



lent in pear trade circles that the Cali- 

 fornia pears contain more sugar. 



If the pears were held from the time 

 of picking until soft ripe at ordinary 

 temperature, rather than in cold stor- 

 age, there was an increase in the amount 

 of acid in the fruit during that time. 

 Pears ripened at cold storage tempera- 

 tures, however, contained about the 

 same amount of acid when ripe that 

 they did at the time of removing from 

 the tree. There was about 1 per cent 

 more sugar in the fruit ripened at 70 de- 

 grees than in that ripened in cold stor- 

 age at 40 degrees. 



Fruit ripened at 70 degrees was richer 

 and better flavored than that ripened in 

 cold storage. Fruit held at 30 degrees 

 for two to three months, then taken out 

 while still hard green and ripened at 

 a temperature of 70 degrees, was richer 

 in sugar and much higher in quality 

 than that held until ripe at temperatures 

 of 40 to 45 degrees. 



Cold Storage Temperatures for Bartlett 

 Pears. 



There is a widespread belief among 

 handlers of Bartlett pears, particularly 

 in California, that this fruit, when put 

 in cold storage, should be held at tem- 

 peratures of 35 degrees to 40 degrees, 

 or even higher. A careful study of the 

 response of the fruit under different 

 temperatures has shown this belief to 

 have no foundation. Pears stored at 

 40 degrees, if put in storage as soon as 

 picked, will last from three to six weeks, 

 depending upon the degree of ripeness 

 at the time of picking and the locality 

 in which they are grown. If allowed to 

 ripen at this temperature they will be 

 lower in sugar and of poorer quality 

 than if handled in any other way. 



Storing at about 30 degrees gave by 

 far the best results for Bartlett pears. 

 Fruit picked while still hard and green 

 and held at this temperature from six 

 weeks to three and one-half months was 

 to all appearances in this condition 

 when removed from storage and re- 

 quired five to six days after placing in 

 a room at 70 degrees before it was in 

 prime eating condition. The quality of 

 this fruit when ripe was much higher 

 than that of fruit stored until ripe at 

 40 degrees. Furthermore, the period 

 that it is possible to hold the fruit is 

 much longer. 



As the Bartlett pear acreage on the 

 Pacific Coast increases, the season, both 

 for fresh shipping and cannery or dry- 

 ing trade, must be lengthened. Cold 

 storage must be utilized more and more. 

 If the following rules for storage are 

 closely adhered to, a product of excel- 

 lent dessert quality, which may be 

 stored for a considerable period, will 

 be obtained. 



1. Leave the fruit on the tree until 

 it has attained a high sugar content. 

 This is not always possible for fruit in- 

 tended for fresh shipment, but for can- 

 ning or drying it is especially im- 

 portant. 



2. Remove the fruit to cold storage 



at once after picking from the tree. 

 Every day at high temperatures after 

 the fruit is picked will shorten its stor- 

 age life very considerably. 



3. Cool the fruit to 30 degrees as 

 quickly as possible. Fruit does not re- 

 ceive the benefit of the low tempera- 

 tures until it is actually at those tem- 

 peratures. Use a pre-cooling room 

 where available to rapidly cool the fruit 

 to the refrigerating temperature. 



4. Hold the fruit at 30 degrees. A 

 few degrees below this temperature the 

 fruit is liable to injury and a few de- 

 grees above will shorten very consid- 

 erably the time it is possible to hold 

 the fruit. 



5. When the fruit is desired for use, 

 remove it from cold storage and allow 

 it to ripen at temperatures of 60 to 70 

 degrees. This will give a higher quality 

 produce than will storing the fruit until 

 ripe at temperatures of 35 to 40 degrees. 



Bartlett pears, picked when well ma- 

 tured but while still hard green and 

 handled according to these suggestions, 

 will readily last two to three months 

 in storage, and in many cases may even 

 exceed this time very considerably. 



The data upon which this article is 

 based and a more complete discussion 

 of the results are given in a paper en- 

 titled "Investigations in the Bipening 

 and Storage of Bartlett Pears," Journal 

 of Agriculture, Besearch, Vol. 19, No. 10, 

 August 16, 1920. 



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