Sugar content and dry matter in potatoes stored under fluctuating temperatures in non-refrigerated stores in Greece

Summary Potatoes were stored in non-refrigerated stores in the Marmarini area (central Greece, altitude about 50 m) and in the Polymylos area (northern Greece, altitude about 900m). In Polymylos, the tubers (cvs Fina and Spunta) were harvested in October 1985 and stored until April 1986; the temperature in the store fluctuated between −1°C and 14°C (mostly between 3°C and 7°C). In Marmarini, the tubers (cvs Sebago and Spunta) were harvested in December 1985 and stored until April 1986; the temperature in the store fluctuated between 0°C and 18°C (mostly between 5°C and 10°C). Every 1–2 months tubers were analysed for dry matter (DM), total sugars (TS) and reducing sugars (RS). In Marmarini, a significant increase of TS and RS was found in both cultivars from December to January, followed thereafter by a significant decrease. In Polymylos, a continuous (from November to April) increase in TS and RS was observed in cv. Fina while in cv. Spunta the sugars increased only until January, followed thereafter until April by a significant decrease.     

Comparison of textural and compositional attributes of green and white asparagus produced under commercial conditions

Maize ogi was supplemented with 10 and 20% toasted and untoasted okra meals. Yields and chemical composition of ogi, and okra meal, and ogi substituted with okra meal were determined. Brabender paste properties of ogi and ogi substituted with okra meal mixtures were determined. Sensory acceptability of cooked colored and flavored ogi pastes was determined. Yields of ogi were 67.8% while yields of the toasted and untoasted okra seed meals were 35.1 and 39.9% respectively. Supplementing ogi with okra meal increased protein,ash, oil and fiber contents, but reduced ogi viscosity. Addition of yellow color did not significantly improve the color rating, but addition of vanilla flavor improved the flavor of ogi supplemented with untoasted okra meal significantly.     

Peeling has no effect on respiration and ethylene production and only minimal effect on quality of fresh white asparagus spears

Fresh white asparagus spears were subjected to peeling or left unpeeled before storage at 10 °C for 7 days. CO₂ and ethylene production rates were determined during storage, while color, toughness and DPPH radical scavenging activity as well as soluble solids, total soluble phenols and nitrate content were determined before and after storage in both peeled and unpeeled spears. Peel CO₂ and ethylene production rates were also determined during storage. Spears subjected to peeling were more tender, and had lower lightness and chroma and higher hue angle values compared to the unpeeled ones. However, both peeled and unpeeled spears had similar DPPH radical scavenging activity, soluble solids, total soluble phenols and nitrate contents. Peeling resulted in increased CO₂ and C₂H₄ production rates, but peel contributed to total increase of CO₂ and C₂H₄ production. As the measured metabolic activity of the peeled asparagus spears was similar to that of the unpeeled, peeling did not adversely affect quality during storage.     

Sugar and dry matter changes in potatoes stored in a clamp in a mountainous region of Northern Greece

Summary Potato tubers (cvs Fina, Marfona and Spunta) were stored in a clamp in the region of Mount Vermion in Northern Greece (altitude about 1400 m) from October 1985 to April 1986. No sprout inhibitor was applied. Tubers were analysed for dry matter and sugar content at 2–4 month intervals. Cultivar and date of sampling had a no significant effect on dry matter but had a significant effect on the total and reducing sugar contents. A significant interaction between cultivar and date of sampling was observed for dry matter and sugars. A continuous increase of total and reducing sugars from October to April was found in tubers of cv. Marfona. In tubers of cvs Fina and Spunta the total and reducing sugars increased, significantly only until March, and thereafter decreased.     

Genotype,ultraviolet irradiation,and harvesting time interaction effects on secondary metabolites of whole lettuce and browning of fresh-cut product

This study evaluated the importance of three factors (genotype, ultraviolet [UV] radiation and harvest time) and their interaction on phenolics, tannins, flavonoids and antioxidant activity of ‘Paris Island’ (romaine type) and ‘Sanguine’ (red leaf type) lettuce plants as well as on the severity of browning of their fresh-cut product. Ten genotypes had significant effect on secondary metabolite accumulation and higher levels were found in ‘Sanguine’, while no interaction effect was found among all the studied factors. Therefore, a new analysis of variance was performed for each genotype separately. The results showed that in ‘Paris Island’ the time of harvest had a significant effect on all measured parameters with higher levels for plants from the night harvest, while UV radiation had little effect on the plants’ biochemistry. On the contrary, in ‘Sanguine’, UV radiation significantly affected the concentration of secondary metabolites and antioxidant capacity, with higher levels for plants grown under UV-open film. Browning evaluation of fresh-cut product derived from the above plants showed that factors affecting secondary metabolite concentration in whole plants at harvest did not have a similar effect. The findings indicate that there are appropriate treatments, for each genotype, that could achieve high production of secondary metabolites and improve their antioxidant properties.     

Sugar and dry matter changes in potatoes overwintered in soil in Greece

Summary Potatoes were left in the soil from December, when the vines died, until February (cvs Claustar and Sebago) or April (cv. Spunta) in a location of central Greece with light, well drained soils and a mild climate. Tubers were analysed every two months for dry matter and sugar content and usually the dry matter content did not change significantly from December to February or April. The reducing sugars increased from December to February in tubers of all cultivars and significantly decreased in cv. Spunta from February to April.