This important subject cannot be treated here at length. In a hot season with abundant crops, good results may be obtained with some prospect of profit. But the apparatus has been expensive. Mr Udale's Report to the Worcestershire C.C. on dried fruits, vegetables and herbs, with the article in Journal of R.H.S., vol. xxvi., part ii., should be consulted, and "Fruit Preserving," by R.L.C., in Watson, vol. v. Thick-skinned plums, e.g., Czar, Prince Englebert, Diamond and Monarch are best for the purpose. Plums placed on trays, dried in a very slow oven, and allowed to cool several times, are often equal to French prunes.
Bottling
This is a simple and most useful process. Plums well bottled will last for years. Gather clean and dry fruit before it is quite ripe, that the heat may not crack the plums. Remove the stalks and pack closely in bottles not over 11 inches high, without bruising, up to shoulder of bottle. Provide a boiler a foot deep; place hay or canvas at the bottom, then put the bottles in the boiler with hay or canvas around them to prevent fracture. Now fill the boiler up to the necks of the bottles, and place it on a slow fire. Heat very gradually until the water is at boiling point. Then take each bottle out with a cloth, fill with boiling water kept close at hand, and cover while boiling with air-tight stoppers. Another method is to fill the bottles nearly full with cold water or thin syrup, and boil for fifteen minutes. Messrs De Luca have received silver and bronze medals from the R.H.S. for self-closing bottles now sold by Messrs Abbott of Southall, near London. Their method is as follows: "Pour in water or cold thin syrup (one tablespoonful of crystalised cane-sugar to the pint) sufficient to cover the fruit. Adjust the indiarubber in the groove made for it on neck of the bottle, place the disc on it, and lightly screw down the outer ring. (Steam must be allowed to escape.) Boil as before for twenty minutes; take out each bottle, and at once screw the outer ring as tightly as possible. Leave bottles until cold. Next day examine by unscrewing the outer ring, and try whether the disc is firmly fastened down. If so, replace the ring, screw down tightly and store away in a cool place, standing them upright. The bottles by having new discs and indiarubber rings may be frequently used."
The Rev. W. Wilks, secretary of the R.H.S., recommends pears, especially Pitmaston D., as suitable for bottling. "Bottled it is delicious." He thinks fifteen minutes from the time the water boils sufficient for plums. Messrs De Luca mention an hour as the time for pears.
Messrs Lee & Co. of 19 Knightrider St., Maidstone, have received medals from the R.H.S. and others for their fruit bottling apparatus and bottled fruit.
They supply a patent economic fruit bottling apparatus at 21s. A thermometer at the side records the temperature of the bottles and of their contents. The following is the method given in the Journal of the R.H.S.
"The fruit must, of course, be fresh and good and the bottles clean. The fruit is first packed into the bottles, which are then filled up to the neck with cold water, or if preferred, with thin syrup made by dissolving ½ lb. of loaf-sugar in hot water and leaving it to cool. The bottles are then put into the cooking pot where they must remain for certainly not less than two hours at a temperature of between a minimum of 145 degrees and a maximum of 160 degrees. This low sterilising temperature being maintained for two, three, or four hours will destroy all germs without cooking the fruit, and is the great secret of successful bottling. No actual harm is done by the heat rising above 160 degrees, but if it does the fruit will probably burst, lose its shape, and not look so nice. Vegetables may be preserved in exactly the same way, but they must be done twice over with an interval of twenty-four hours to allow of their becoming quite cold. Jams and fruit jellies can be preserved fresh and good for years in the same way."
Success in bottling and preserving fruit depends chiefly on two points: (1) The destruction of every germ of mildew, etc., by keeping the bottles at a certain temperature for a certain time; (2) the absolute prevention of any possible re-entry of air into the bottles afterwards. The bottles must be hermetically sealed while in the steam or standing in almost boiling water (see Journal R.H.S., vol. xxvi. part iii. p. 365).
Bottling or Canning in Syrup.—This is done by boiling together at the rate of 3 lbs. of cane-sugar to 1 quart of water and the white of 1 egg; pour the fruit whole into the syrup while boiling, and continue to boil together for only a few minutes, then pour into bottles or cans, and stopper or seal air-tight immediately whilst boiling. Pears may be preserved in the same way. Cheal, Journal of R.H.S., vol. xxi. 1.
Plum Jam makes a rich preserve. Take equal quantities of fruit and cane-sugar; boil quickly half to three-quarters of an hour, then put into hot jars and cover well at once. Exclude the air as much as possible. The colour of the flesh is said to make a difference in the sale. Red jam is usually preferred, but greengage is also popular. Coe's Golden Drop or Autumn Compôte (September, hardy, fairly productive, but the fruit often splits) are good for yellow ("Amber"—Dr Hogg) jam; Belle de Septembre (September, "a good late cooking variety," good bearer, but fruit prone to split) for crimson colour. Free-stones are better than cling-stones. The following are free-stones: Bittern, Coe's Late Red ("fruit small, good bearer, a very useful late cooking plum"), Early Orleans, Early Transparent Gage, Old Greengage, Orleans, Oullin's Golden Gage, Red Magnum Bonum, Comte d'Althann, Victoria. The following are nearly so: Early Prolific, Czar, Cox's Emperor, Jefferson.