| Raspberry(Rubus idaeus L.)is a kind of nutritious fruit and a good source of polysaccharides.Various kinds of bioactive compounds of raspberry were proved to be functional in keeping healthy,however,the research about the effects of raspberry on intestinal health were seldom concerned.In this study,the process for preparing red raspberry extract was optimized after the nutrient composition of red raspberry was determined.The effects of using red raspberry extract and synthetic medium to culture probiotics in vitro was compared by turbidimetric method and transcriptome sequencing technique.On this basis,the different concentrations of raspberry extract and their combination with different lactic acid bacteria were used as gavage of several groups of kunming mice.The mice intestinal flora diversity in was estimated by means of high-throughput sequencing technology after 28-day of intragastric administration.The histologic section of liver and intestinal tissue of mice were observed using microscope.The purpose of this study is to provide theoretical basis for the deep processing of raspberry.The main research results are listed as follows:(1)There are abundant microelements in fresh fruit of raspberry Heritage,such as calcium,iron,potassium,phosphorus and so on.The carbon source is adequate in raspberry fruit,since the monosaccharide content was 4.74 g/100g,and the crude polysaccharide content was 0.21%,which was lower than other published results.Therefore,the polysaccharide extraction process was optimized in the following experiments.(2)The optimal parameters for preparation of raspberry extract were chosen by single factor test,response surface test and orthogonal test.The optimum extraction parameters were determined as material/liquid ratio 1:4.04,water bath temperature 75.05°C,ultrasonic time 24.82 min.Optimal reaction condition of complex enzyme was at p H 4.5 and reaction temperature 45°C in 1 h.The best yield of raspberry crude polysaccharide was 10.30%under optimal conditions.(3)The stable phase of Lactobacillus plantarum(L.plantarum)121 was delayed by 2h when the strain 121 cultured in raspberry extract medium compared with in MRS medium.The maximum colony number of L.plantarum 121 cultured in raspberry extract medium was 6.60×10~9 CFU/m L,while the maximum colony number of MRS medium was 5.84×10~9CFU/m L.When cultured in raspberry extract medium,the growth cycle of Bifidobacterium longum(B.longum)1.2186 was similar to that in BBL culture medium.But the concentration of strain cells in raspberry culture medium was higher than that in BBL culture medium after 10 h.The maximum colony number of B.longum 1.2186 cultured in raspberry extract medium was 5.94×10~9 CFU/m L and that in BBL culture medium was5.34×10~9 CFU/m L.(4)Compared with L.plantarum 121 cultured in MRS medium,the strain cultured in raspberry extract medium presented 255 up-regulated DEGs and 292 down-regulated DEGs.The significantly up-regulated GO enrichment about molecular function was mainly related to the serine,threonine and carbohydrate metabolism enzymes.GO Enrichment related to biological processes was significantly up-regulated in the aspects of metal ions(such as potassium ions)transportation and polyol metabolism,and protein catabolism metabolic processes.The significantly up-regulated GO enrichment referred to cell component was about protease complex,peptidyl endonuclease complex,threonine type peptidase activity and cell wall.It was found that the up-regulated KEGG enrichment was involved in metabolism of starch and sucrose,glyceride metabolism,which suggested that the raspberry extract promote the growth of the strain 121 by affecting enzymes involved in amino acid and sugar metabolism.(5)It has been shown that the intake of the low level of raspberry extract(containing10%of raspberry crude polysaccharide)could significantly increase the activity ofβ-glucosidase of bacteria in the mice fece.After 28 days of feeding,the microbial diversity in mice feces was studied by high-throughput sequencing technology.On the phylum level,the relative abundance of Actinomycetes in all the experimental groups has increased,but the group with intake of low-level raspberry extract accompanied with L.plantarum 121 showed the largest increase of 0.025.Overall,the intestinal microbial diversity of mice fed by red raspberry extract combined with Lactobacillus plantarum 121 was extremely improved.(6)The raspberry extract and their combination with LAB could help control the total cholesterol(TC)in mice at a lower range.The raspberry extract and their combination with LAB showed the potential of reducing aspartate amino transferase(AST)activity in serum,while the high level of red raspberry extract could restore the activity of alanine transaminase(ALT)in mice serum to a normal range.These data suggest that red raspberry extract or red raspberry extract combined with probiotics have a positive effect on liver function in mice.According to the observation of tissue sections,it was confirmed that the intake of raspberry extract was not harmful to the intestine and did not cause liver toxicity.In this study,the raspberry extraction process was optimized,and the effects of raspberry extract alone or with probiotics on the intestinal environment and other physiological indicators of mice were explored.The above conclusion is illuminating for the further processing of raspberry and could find out a high-value utilization method to rise up the added value of raspberry products. |
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