Effects of Simulated Acid Rain on Main Nutritional Indicators of Three Leafy Vegetables

The purpose of this paper was to identify content changes in the main nutritional indicators of three common leafy vegetables, and to provide a theoretical basis for the protection of leafy vegetables from acid rain. The experiment investigated the effects of simulated acid rain on four main nutritional indicators, including soluble sugar, total free amino acid, soluble protein and vitamin C during the application of simulated acid rain(SAR) in pakchoi(Brassica rapa chinensis), rape(Brassica campestris L.) and lettuce(Lactuca sativa Linn. var. ramosa Hort). The vegetables were respectively exposed to SAR of pH=7.0, 5.6, 5.0, 4.0, 3.0 and a control level of pH=6.5. The concentrations of the four main nutritional indicators were determined at harvest. The results show that nutritional quality of the three leafy vegetable species decreased with the declining of pH values of SAR. The higher the acidity of SAR was, the more significant the inhibitions were. Nutritional quality of lettuce was the most affected by simulated acid rain, followed by pakchoi and rape. The change range of soluble protein content was higher than those of the other three indicators’ contents, which indicates that soluble protein is most sensitive to simulated acid rain.

Fermented Spirulina products with Saccharomyces and non- Saccharomyces yeasts:Special reference to their microbial,physico-chemical and sensory characterizations

Innovative products produced from various sources through fermentation processes have been a resurgence of interest.This study was designed to determine the performance of fermented Spirulina (FS) products by three different yeast species including Debaryomyces hansenii ,Kluyveromyces marxianus and Saccharomyces cerevisiae and investigate the microbial,physicochemical and sensory characteristics of products.The results showed that the increase in yeast cell number was around 3 log after 48 h fermentation in Spirulina medium without additional carbon source.Protein bands with a molecular weight of ∼51 kDa seemed less visible and bands 14–22 kDa disappeared after 48 h fermentation by K.marxianus showed strong hydrolysis of proteins during fermentation.The amino acid compositions of the three kinds of FS were different also compared to unfermented Spirulina (unFS).Glutamic acid,methionine,lysine,isoleucine and valine became more dominant in FS samples.According to GC–MS analysis,there was a decrease in the concentration of pyrazine,ketone and aldehyde compounds of FS compared to unFS.The flavor notes of “seaweed”,“cardboard”,“earthy/muddy” and “cereal/straw” were found to be the highest in unFS than in FS detected by panelists during sensory evaluations.FS by K.marxianus is highly characterized as having the lowest “seaweed” and “umami” flavor attributes and higher “fermented” and “rose” attributes.Finally,the current study revealed that the potential of Spirulina biomass to be a suitable substrate for yeasts and fermentation of Spirulina with different yeast species led to different kinds of products.