Sorbitol 70% solution non-crystallising

The search to improve the characteristics of biomaterials obtained from natural biopolymers such as starch has led to the use of mixtures of various polymers with plasticizing agents such as glycerol and sorbitol. In this research, the effect of concentration (10, 20, 30, 40 and 50% starch basis) and type of plasticizer (glycerol and sorbitol) on water solubility (WS), total color difference (ΔE), mechanical properties and water vapor permeability (WVP) of films based on sweet potato starch was evaluated. The mechanical properties were determined by the Puncture Strength method, WVP and WS were performed using gravimetric methods, ΔE was determined by a colorimeter. The results showed an inverse relationship between the puncture resistance and ΔE of the films with the concentration of the plasticizers. However, an increase in plasticizer concentration led to an increase in the percentage of elongation, WS, and WVP of sweet potato starch films. The highest values for percentage elongation and WVP were found in films plasticized with glycerol. Sweet potato starch can be used for the development of film for edible candy wrappers and edible coatings fresh fruit and vegetables.

Abstract licence: CC BY-NC-ND

Sweetness is one of the main drivers of consumer preference, and thus is given high priority in apple breeding programmes. Due to the complexity of sweetness evaluation, soluble solid content (SSC) is commonly used as an estimation of this trait. Nevertheless, it has been demonstrated that SSC and sweet taste are poorly correlated. Though individual sugar content may vary greatly between and within apple cultivars, no previous study has tried to investigate the relationship between the amount of individual sugars, or ratios of these, and apple sweetness. In this work, we quantified the major sugars (sucrose, glucose, fructose, xylose) and sorbitol and explored their influence on perceived sweetness in apple; we also related this to malic acid content, SSC and volatile compounds. Our data confirmed that the correlation between sweetness and SSC is weak. We found that sorbitol content correlates (similarly to SSC) with perceived sweetness better than any other single sugar or total sugar content. The single sugars show no differentiable importance in determining apple sweetness. Our predictive model based on partial least squares regression shows that after sorbitol and SSC, the most important contribution to apple sweetness is provided by several volatile compounds, mainly esters and farnesene.

Abstract licence: CC BY

Both sorbitol and sucrose are synthesized in source leaves and transported to fruit for supporting fruit growth in tree fruit species of the Rosaceae family. In apple (Malus domestica), antisense suppression of aldose-6-phosphate reductase, the key enzyme for sorbitol synthesis, significantly decreased the sorbitol concentration but increased the sucrose concentration in leaves, leading to a lower sorbitol but a higher sucrose supply to fruit in these plants. In response to this altered carbon supply, the transgenic fruit had lower concentration of sorbitol and much higher concentration of glucose but similar levels of fructose, sucrose, and starch throughout fruit development relative to the untransformed control. Activities of sorbitol dehydrogenase, fructokinase, and sucrose phosphate synthase were lower, whereas activities of neutral invertase, sucrose synthase, and hexokinase were higher in the transgenic fruit during fruit development. Transcript levels of MdSOT1, MdSDHs, MdFK2, and MdSPS3/6 were downregulated, whereas transcript levels of MdSUC1/4, MdSUSY1-3, MdNIV1/3, MdHKs, and MdTMT1 were upregulated in the transgenic fruit. These findings suggest that the Sucrose cycle and the sugar transport system are very effective in maintaining the level of fructose and provide insights into the roles of sorbitol and sucrose in regulating sugar metabolism and accumulation in sorbitol-synthesizing species.

Abstract licence: CC BY