Stevioside

Stevia rebaudiana Bertoni is a branched bushy
shrub  of  the  Asteraceae  family,  native  to  the  Amambay
region  in  the  northeast  of  Paraguay.  Stevioside  and  re-
baudioside  A  are  the  main  sweetening  compounds  of
interest, which are commercially produced by both chem-
ical  and  physical  processes.  S.  rebaudiana  has  a  great
potential  as  a  new  agricultural  crop  since  consumer
demand  for  health  promoting  foods  is  increasing,  and
proximate  analysis  has  shown  that  Stevia  also  contains
substantial  amounts  of  proteins,  potassium,  and  other
essential nutrients. Stevia can be taken in as a carbohydrate
diet source without calories. This paper provides an over-
view  of  structure  and  properties  of  stevioside,  various
extraction  techniques,  applicability  in  food  industry,  and
recent technological advances achieved.

Stevia rebaudiana a perennial shrub of genus Stevia and family Asteraceae is a plant, native to Paraguay while it has been grown in many countries around the world for commercial purpose. The leaf extract of stevia has a sweet taste profile resulted by a group of chemical compounds called Glycosides. Stevia extract is used as a natural sweetener which replaces the sugar or can be marketed as a non-caloric sweetener. The diterpene glycosides in the Stevia leaf extract are responsible for the sweet taste whereas the main responsible glycosides for the sweetening property are Stevioside and Rebaudiosides A. The bitter aftertaste and the natural licorice taste in Stevia is due to high Stevioside/ Rebaudiosides A ratio. Therefore, a promising sugar substitute for the market can be made with a low ratio of Stevioside/ Rebaudiosides A which can be achieved through different techniques such as enzymatic glycosylation and breeding between desirable genotypes. Stevia is used in food industry, medicine industry and by product industry (fertilizer, animal feed). In addition to its sweetening property, Stevia has numerous therapeutic effects including anti-diabetic, anti-hypertension, anti-cancer, antioxidant, antiobesity and anti-microbial effects. However, there are several controversial ideas on the safety of Stevia consumption in humans while many studies in-vitro and in-vivo have revealed no health risk in consumption of Steviol glycosides.

In order to cope with challenges linked to climate change such as salinity, plants must develop a wide spectrum of physiological and molecular mechanisms to rapidly adapt. Stevia rebaudiana Bertoni plants are a case in point. According to our findings, salt stress has no significant effect on plant growth in these plants, which accumulate sodium (Na þ) in their roots, thus avoiding excessive Na þ accumulation in leaves. Furthermore, salt stress (NaCl stress) increases the potassium (K þ), calcium (Ca 2þ), chloride ion (Cl À) and proline concentrations in Stevia leaves, which could contribute to osmotic adjustment. We also found that long-term NaCl stress does not produce changes in chlorophyll concentrations in Stevia leaves, reflecting a mechanism to protect the photosynthesis process. Interestingly, an increase in chlorophyll b (Chlb) content occured in the oldest plants studied. In addition, we found that NaCl induced reactive oxygen species (ROS) accumulation in Stevia leaves and that this accumulation was more evident in the presence of 5 g/L NaCl, the highest concentration used in the study. Nevertheless, Stevia plants are able to induce (16 d) or maintain (25 d) antioxidant enzymes to cope with NaCl-induced oxidative stress. Low salt levels did not affect steviolbioside and rebaudioside A contents. Our results suggest that Stevia plants induce tolerance mechanisms in order to minimize the deleterious effects of salt stress. We can thus conclude that saline waters can be used to grow Stevia plants and for Steviol glycosides (SGs) production.

A field experiment was conducted at the Experimental farm, Soils and water Department, Faculty of Agric., Al-Azahar Univ., Assuit, Egypt, during two successive growing seasons of 2018 and 2019. The study aims to assess the influence of organic food wastes (Eggshell, Banana peels, Green pea peels and Potato peels) are sources of some nutrients and Soybean protein isolate as a source of nitrogen on the soil fertility, growth parameters, yield and quality of stevia plant under drip irrigation system.
The result showed positive increase in all growth parameters and yield of sativa plant as well as improving soil properties by adding organic food wastes. The most effective treatment was the combination of C4 treatment (50% organic-N from isolated soy protein, 12.5% banana peels, 12.5% eggshell, 12.5% green pea peels and 12.5% potato peels). The highest total chlorophyll value of 4.48 and 3.61 mg/g fresh weight in the 1stand 2nd cutting, respectively in the 1st season were obtained under C4 treatment. The corresponding values were 4.89 and 4.02 mg/g fresh weight in the 2nd season. The highest values of dry leaf yield 843 kg plot-1 and biological yield 1.60 kg plot-1 were noticed under C2 treatment in the 2nd cut in the first season. In the second season, the corresponding values were 1242 and 2.19 kg plot-1 resulted from C4 treatment in the 2nd cut. The highest values of protein content 10.73 and 13.72% in 1st and 2nd cut, respectively were realized under C4 treatment in the 1st season. The corresponding values were 15.0 and 18.11% for C4 treatment in the 2nd season. In the 1st season, the highest values of stevioside content were 8.49 and 8.98 % in the 1st and 2nd cut for C4 and C2, respectively. In the 2nd season, the highest values of stevioside content were 9.69 and 10.05 % in the 1st and 2nd cut for C2 treatments, respectively. Available N in C0 treatment Control (without applied fertilizers) had the lowest values of both seasons compared to the C4 treatment that had the highest values of both forms in both seasons. The overall results suggest that organic food wastes combination could be advised to grow stevia plant and improving soil properties of Egypt.