Book reviews

Foods, nutrients and food ingredients with authorised EU health claims. M.J. SADLER (Ed.). Woodhead Publishing is an imprint of Elsevier, Cambridge, UK, Waltham, US, Kidlington, UK, Series in Food Science, Technology and Nutrition: Number 263, 2014 ISBN 978-0-85709-842-9 (print), ISBN 978-0-85709-848-1 (e-book), 397 page

The effect of harvesting time on the biochemical and ultrastructural changes in Idared apple

Apples were harvested at three different times (1 st, 2 nd and 3 rd) then stored at 1-3 °C, 85-90% R.H. for 5 months. Firmness, ethylene productivity, the distribution of calcium and potassium and the ion leakage were measured. The ultrastructure of the cell wall was studied by SEM and TEM and he activity of β-galactosidase and polygalacturonase and pectin content were determined. The ethylene evolution of fruits decreased by the harvest and storage time. At the beginning of storage, the ethylene productivity in the 1 st harvest apple increased up to a maximum value then declined. The 2 nd harvest fruits produced less ethylene than that observed in 1 st harvest fruits. No ethylene production was found in the 3 rd harvest fruits. Firmness was different according to harvest time, but that difference disappeared during storage. The permeability of membranes increased as a function of harvests and storage. The distribution of calcium was typical at the beginning, the highest concentration of calcium being near the core and skin, but by the end of the storage calcium moved from the skin towards the core. Potassium content was the highest near the core and decreased towards the skin, both in the fresh and stored apples. The activities of polygalacturonase and β -galactosidase were not influenced by the harvest time, but changed as a function of storage time. The autolysis of pectin and soluble carbohydrates increased during storage, mostly in the 3 rd harvest. At the beginning of storage, the cell wall and middle lamellae of the 1 st harvest fruits' flesh were not damaged. Large degradation of the middle lamellae was observed in the 2 nd and 3 rd harvest fruits. Lower membrane permeability, pectin degradation and PG enzyme activity were found in the 1 st harvest apples. The Idared apple should be harvested close to the climacteric maximum for better and longer storage

Ripening and microstructure of apricot (Prunus Armeniaca L.)

Colour, texture, pectin autolysis, membrane permeability and microstructure (SEM, TEM), β-galactosidase and polygalacturonase were studied in apricots (cv. Magyar kajszi) harvested in mature green, straw yellow, bright orange and deep orange stages. The L* increased from mature green to straw yellow then decreased from straw yellow to deep orange state. The a* values increased with ripening. The bright and deep orange apricots were significantly softer than the mature green and straw yellow ones and the membrane permeability increased with ripening. The presence of β-galactosidase enzyme was proved by immunoblotting analysis using monoclonal anti-β-galactosidase clone GAL-13 (Sigma) in all ripening stages. The enzyme activity was very low in mature green stage and increased significantly (P>95%) with increasing ripeness and during storage. The PG activity was very low in the mature green apricot. A significant (P>95%) increase was observed in the straw yellow apricot and in the riper fruits. The mature green apricot showed a regular, the straw yellow and bright orange samples showed a moderately regular tissue structure, while the tissue of the deep orange apricot collapsed (SEM). The cell wall and the middle lamella of the green apricot (TEM) were intact. Generally, there were intact cytoplasm membranes with some damaged parts. In the straw yellow apricot, the cell wall started to loosen, the middle lamella lost pectic polysaccharides. The structure of the cytoplasm was not recognisable, the tonoplast and the cytoplasm membrane were injured. The cell wall of the bright orange apricot was similar to that of the straw yellow ones. The middle lamella dissolved and hairy, fibrillar structure of cell wall was found in the deep orange samples

Fructo-oligosaccharide degradation in apple pulp matrix

The degradation process of fructo-oligosaccharides (Raftilose® P95) has been studied in apple pulp matrix at 70–80 °C in pH range 2.7–3.3. Changes of sugar compositions have been analysed by an appropriate isocratic HPLC with differential refractive index detector for oligosaccharide determination. According to Arrhenius equation significant effect of temperature has been observed on the decrease of oligomer concentration. The oligomers (DP3-DP7) degrade continuously at any pH between 2.7 and 3.3. The lower the pH the higher the change of oligomer and monomer concentration is. The oligomers (DP4-DP7) could give out in 30–40 min below pH 3.0 caused by the high concentration of protons. The rate of degradation depends not only on the processing time, temperature, and the proton concentration of the solution, but on the characteristic of apple pulp, too, where the degradation is significantly higher than that in water solution