UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION CIRCULAR No. 259 April, 1923 PEAR BY-PRODUCTS By J. H. IRISH The latest government reports show that a crop of about five hundred thousand tons of pears is produced in the United States annually. Of this amount, the part produced in California is about one hundred and forty thousand tons. The marketing of this fruit already presents a difficult problem, although only one-half of the plantings of pear orchards in this state have come into bearing. Any new outlet for pears is, therefore, worthy of consideration. Disposal of Pears of Better Quality. — First class fruit is shipped east as fresh fruit from some localities and that from other localities is canned. In Lake County, which produces pears of remarkably fine quality and where the transportation facilities are poor, practically all of the pears are dried. Disposal of Culls. — In the Sacramento Valley the cull pears amount to about three thousand tons annually. The total for the state is estimated by the Pear Growers' Association at fifteen thousand tons. At present, cull pears are dried and yield a product of very poor quality or they are sent to the refuse heap. We may expect that the production of pears in the state will have doubled within the next five years. To be profitable this increase in production will require a great expansion of the market or a limitation of shipments by very close grading which will allow fruit of only the finest quality to reach the market. It must be accompanied by improvements in cultural methods, which will produce fruit of better quality and eliminate culls, or by finding new outlets for the great increase of culls. The purpose of the investigations reported in this publication is to discover new outlets for these culls in the form of pear by-products. Culls consist of malformed, insect injured, sunburned, or otherwise blemished fruit which can neither be shipped as fresh fruit nor canned. Culls infested with Codling Moth are of little value for by-products because of the great cost of trimming out affected portions of the fruit. 2 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION PEAR SPREAD Experiment Work. — A product which has proved very satis- factory and which has possibilities of becoming of commercial value is "Pear Spread." It is called "Pear Spread" in preference to "Pear Butter," because its quality is superior to that of the old- fashioned fruit butters. The method recommended for making this product was developed in the Fruit Products Laboratory by blending small quantities of pear pulp with various combinations of spices and varying propor- tions of sugar. The concentration was varied by cooking for varying times. The samples were tested by members of the Fruit Products class, members of the staff and visitors. Samples made by the process and formula given below met with general approval. During the season of 1921 about one-half ton of pears, furnished by Mr. F. T. Swett of the Pear Growers' Association, was made into this product. Part was used for experimental purposes in determin- ing the heat penetration, processing temperature, keeping qualities, and other factors of the process. The remainder was sold in Berkeley. During the 1922 season two and one-half tons of cull pears was obtained from the Pear Growers ' Association at a moderate cost. This was made into ' ' Pear Spread ' ' according to the process which follows. Process. — (a) Preparation of Fruit. The fruit is washed, and stems, decayed spots, dirt and worm traces removed. It is then run through an apple grater and placed in the kettle. For the experiment lot a steam jacketed kettle was used. Direct flame and other types of kettle may be used if proper precautions are taken to prevent scorching. If the fruit is green, about one gallon of water is added to each five-gallon lot of pulp. Thoroughly ripe pears require no water. When no water is added less cooking is necessary in the final concentration. When the pulp is soft it is removed from the kettle and run through a cyclone tomato pulper, using the coarse screen. This removes the seeds, hard tissues surrounding them, stems, other large hard pieces, and a few of the larger stone cells. Passing it through this screen a second time removes some of the stone cells which were forced through during the first operation. When all the pulp has been screened twice, the coarse screen is replaced by a finishing screen. Passing through this fine screen twice removes most of the stone cells and makes the pulp smooth. (b) Cooking. This smooth pulp is returned to the double jacketed steam kettle for final cooking. The amounts given in the following formula are suitable for a ten-gallon kettle. Circular 259] PEAR by-products 3 Formula Ingredient Amount used Pear pulp 6 gallons Cane sugar 24 pounds Lemon juice 1 quart Ground cinnamon % ounce Ground cloves % ounce Ground ginger '% ounce Ground nutmeg % ounce First the sugar is added to the pulp in the kettle and stirred until entirely dissolved. This mixture is boiled, with continual stirring, until the desired consistency is reached, which is at about 221° F. Lemon juice is then added and boiling continued until the desired consistency is again reached at 221° F. It is then removed from the fire and spices added, and stirring continued until the spices have been thoroughly mixed. This condition is reached when no lumps appear in the product and when it presents a smooth, creamy appear- ance. It is placed in cans and sealed while hot. If sealed before the temperature drops below 185° F., no further processing is necessary. (c) Sterilizing. If allowed to cool before filling the cans, steriliza- tion is necessary. Number 2 cans require boiling in water one and one- half hours at 212° F., for safety. Experiments show that at least seventy minutes' heating in boiling water is necessary to heat the center of a Number 2 can of "spread" to a temperature of 175° F., from an initial temperature of 60° F. The following containers have been found satisfactory : Number 2 tin can, net contents 24 ounces. Number 1 tall tin can, net contents 20 ounces. Jam can, net contents 8 ounces. Vacuum sealed jelly glass, net contents 4 ounces. Vacuum sealed jelly glass, net contents 6 ounces. PEAE VINEGAB* Cull fresh pears yielded a very good vinegar of four and one-half per cent acetic acid content. The fruit was crushed and pressed and the juice fermented with a selected cider yeast. After the completion of the yeast fermentation, a starter of strong cider vinegar, about twenty per cent by .volume, was added, and the barrel containing the liquid left at room temperature for the completion of the vinegar fermentation. This required about three months. Natural fermen- * The experiments on pear vinegar and syrup were made by W. V. Cruess and those on pear candies by J. B. Vance. 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION tation of pear juice gave a weak vinegar of poor flavor and appear- ance. The use of selected yeast, therefore, appears to be necessary. It was found possible by fermenting the crushed, unpressed pears with selected yeast before pressing to greatly increase the yield of juice and to facilitate the pressing operation. A ton of cull pears will yield about one hundred and forty to one hundred and fifty gallons of finished vinegar. Specific directions for the manufacture of vinegar may be found in Bulletin Number 287, sent free on application to the College of Agriculture, Berkeley. PEAR CANDY Pear spread, combined with apple pectin and boiled to 224° F., makes a pleasing candy center. This may be coated with fondant, or chocolate, or both. Sun-dried and dehydrated pears of high quality were dipped in chocolate and were found to give very satisfactory candies suitable for "five cent sellers." The process used was as follows: Soft, pliable dried pears were used. Dipping chocolate, known as the dark amber grade, was melted in a pan placed in water at 85-95° F. (not above 95° F.). The pears were dipped in this melted chocolate and spread on wax paper to permit hardening of the chocolate. It is believed that this product has commercial possibilities. PEAE SYEUP Pears were crushed, pressed, and the juice thus obtained was boiled and filtered. It was concentrated in an open jelly kettle, yielding a syrup of dark amber color and pleasing baked pear flavor. The addition of sugar before concentration at the rate of about three pounds to the gallon of juice increased the yield without impairing the quality. Without the addition of sugar about twenty to twenty- five gallons of syrup to the ton of fruit is obtainable. The syrup should be suitable for table use and cooking. EQUIPMENT Most canneries and jelly factories possess the necessary equipment for preparing pear spread and pear syrup. Pear candies can be made in any candy factory or in the home kitchen without special equip- ment. Existing cider vinegar factories could use cull pears for vinegar without interfering with the crushing of apples, since these ripen later than pears.