Development of a technology of fat-and-oil products from plum kernels

A number of plum cultivars have been analysed as a source of raw materials to obtain oil from the kernels of plum stones. As a result, it has been found promising to study the kernels of plums extracted from the cultivars Friar, President, Greengage (Reine Claude), and Uhorka, because these varieties are most often used in the fruit-processing industry.

The operating modes have been improved, with the introduction of wet-heat treatment. When processed, the crushed plum kernels were moisturized with steam before they entered the press. To overcome or weaken the forces that bind oil with the upper parts of the crushed kernels, and to facilitate its separation from the oil-free components, we use wet-heat treatment. This process consists in treating the crushed kernels with hot vapour, which is accompanied by intensive stirring, to obtain a sufficiently heated and moisturized product termed mash. The temperature and duration of the wet-heat treatment of the kernels were as follows: for the cultivars Friar and President – 40–50 °C, τ 10–15 min, followed by pressing at 50–60 °C for 3–8 min; for the cultivars Greengage and Uhorka – 45–55 °C, τ 15–18 min, followed by pressing at 55–65 °C for 5–8 min.

The oilcake piece was the thinnest in the cultivar Greengage – 21 mm, and the thickest in the cultivar Friar – 25 mm. The data obtained are positive and prove the high performance of the operating modes used.

Sensory assessment of the oil and oilcake was carried out for the kernels of each plum cultivar. The appearance and smell of all the samples were rated 5 points. Almost the same was the score of the colour and consistency in all the cultivars. However, the taste scores were quite different. The lowest score was that of the oil and oilcake from the cultivar Uhorka, because its oil had a bitterish shade of taste.