الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 150 |  |  |
| | | from | 150 | | |
Abstract
Prebiotics regarded as non-digestible food components and have health-promoting influence on host because of their features that are selectively encourage reproduction or activity of bacterial populations requested in the colon. Most potential prebiotic food ingredients are carbohydrate-based components such as oligosaccharides. When prebiotics are used in combination with probiotics or live bacteria, the resultant has synergistic effects, called “synbiotic”. This is because in addition to the action of probiotics that promote the growth of existing strains of beneficial bacteria in the colon, different types of prebiotics also act to improve the survival, implantation and growth of newly added probiotics strains. Therefore, the objectives of this study were investigating the effect of both inulin and maltodextrin as prebiotic substances on some probiotic lactic acid bacteria in Basel medium and skim milk medium along incubation period and attempt to use inulin and maltodextrin as prebiotic substances in production of symbiotic fermented milk containing some probiotic strains. To achieve the objectives of study, the work was planned in two parts as follows:
Part I Effect of different polysaccharides (inulin and maltodextrin) as Prebiotics on growth of some probiotic strains in basal and reconstituted skim milk media:
In this part, four selected probiotic strains (Lb. acidophilus LA-5 100021, Lb. helveticus LH-B02 501699, Lb.plantarum ATCC14917 and Lb. rhamnosus ATCC7469) were tested to grow in normal MRS medium and modified medium replaced the sugar in media (glucose) with two different prebiotics (inulin, or maltodextrin) as source of carbohydrates in basal media. Also the same probiotic strains were cultured at 37 °C for 24 h in 12% (w/v) modified reconstituted skimmed milk containing 5% (w/v) inulin or maltodextrin. The tested to grow in normal skim milk and
85
SUMMARY AND CONCLUSION
Reda Mohamed Elkomaily (2022), M.Sc. Fac., Agric., Ain Shams Univ.
skim milk replaced the sugar with two different prebiotics as source of energy which was inulin or maltodextrin. The results indicated that:
1- Relative growth (%) of Lb. acidophilus LA-5 100021, Lb. helveticus LH-B02 501699, Lb. plantarum ATCC14917 and Lb. rhamnosus ATCC7469 in basal broth medium supplement with 2% inulin were 93.0, 88.6, 69.6 and 75.7 % respectively.
2- Replacement the sugar (glucose) from MRS broth medium with inulin did not affect the growth of strains Lb. acidophilus LA-5 100021 and Lb. helveticus LH-B02 501699
3- Inulin had a negative effect on the growth of strains Lb. plantarum ATCC14917 and Lb. rhamnosus ATCC7469.
4- Relative growth (%) of Lb. acidophilus LA-5 100021, Lb. helveticus LH-B02 501699, Lb.plantarum ATCC14917 and Lb. rhamnosus ATCC7469 in modified MRS broth medium supplement with 2% maltodextrin were 86.1, 81.3, 68.3and 61.5 % respectively.
5- Replacement the sugar (glucose) from MRS broth medium with 2 % maltodextrin as a prebiotic did not affect the growth of strains Lb. acidophilus LA-5 100021 and Lb. helveticus LH-B02 501699
6- Maltodextrin had a negative effect on the growth of strains Lb. plantarum ATCC14917 and Lb. rhamnosus ATCC7469.
7- The results indicated that, replacement the lactose sugar from skimmed milk media with inulin as a prebiotic did not affect the growth of strains Lb. acidophilus LA-5 100021 and Lb. helveticus LH-B02 501699.
8- Inulin had a negative effect on the growth of strains Lb. plantarum ATCC14917 and Lb. rhamnosus ATCC7469 in modified skim milk growth media.
86
SUMMARY AND CONCLUSION
Reda Mohamed Elkomaily (2022), M.Sc. Fac., Agric., Ain Shams Univ.
9- Replacement the lactose sugar from skimmed milk media with Maltodextrin as a prebiotic did not affect the growth of strains Lb. acidophilus LA-5 100021 and Lb. helveticus LH-B02 501699.
10- Maltodextrin had a negative effect on the growth of strains Lb. plantarum ATCC14917 and Lb. rhamnosus ATCC7469 in modified skim milk growth media.
15- It could be concluded that, inulin and Maltodextrin could be used as prebiotics to stimulate the growth of some probiotic strains used in this study in basal and skim milk media.
Part 2: Production and properties of novel synbiotic Fermented Milk:
The present experiments implemented in this part were carried out to apply the results achieved through the pervious part of this study. Functional fermented milk (synbiotic-fermented milk) were made using probiotic strains with and without two of selected prebiotics (inulin and maltodextrin) as well as compared with traditional starter (Str. thermophilus and Lb. delbrueckii ssp. bulgaricus 1:1). The results showed that:
1- The type of starter culture used in production of different treatments did not effect on the dry matter content in the different synbiotic-fermented milk product.
2- Adding inulin or maltodextrin as prebiotic to different synbiotic-fermented milk gave a close result compared to adding skim milk powder in dry matter content.
3- Dry matter content slightly varied among the treatments and both control samples along the storage period.
4- Variation of starter culture used and the inulin and maltodextrin addition had no significant effect on the fat content of the different synbiotic-fermented milk.
87
SUMMARY AND CONCLUSION
Reda Mohamed Elkomaily (2022), M.Sc. Fac., Agric., Ain Shams Univ.
5- Ash content slightly varied among the treatments and both control samples along the storage period.
6- Generally, the ash content varied from 0.764% to 0.807% in fresh synbiotic-fermented milk samples which has been slightly increased to 0.789 to 0.834 at the end of storage period.
7- Synbiotic fermented milk supplemented with natural skim milk powder highest SN/TN content than inulin or maltodextrin without prebiotic
8- Generally, SN/TN content varied from 0.697% in (C) to 0.699% in (T3) fresh samples followed by gradual increase among the storage period to range from 0.721% to 0.726% at the end of the storage period.
9- The TA (%) of fresh synbiotic-fermented milk sample highest TA was recorded on synbiotic fermented milk incorporated with 2% maltodextrin inoculated 2% yoghurt starter culture (T3).
10- Generally, the pH values decreased and the TA gradually increased in all treatments and control samples along the storage period.
11- Adding the inulin or maltodextrin to synbiotic-fermented milk caused an increase in the titratable acidity subsequently decrease in pH value.
12- In general, pH reduced, and TA gradually increased in all treatments and control samples during the storage period. Fermented milk samples made with yoghurt starter culture had the highest value of acidity and lowest pH than the other treatments.
13- There were significant differences in diacetyl and acetaldehyde contents between all treatments.
14- Acetaldehyde contents were significantly higher in T7, T8, T6 and T4 synbiotic-fermented milk samples and also diacetyl contents were
88
SUMMARY AND CONCLUSION
Reda Mohamed Elkomaily (2022), M.Sc. Fac., Agric., Ain Shams Univ.
significantly higher in T5, T4, T3 and T8 synbiotic-fermented milk samples .
15- Using probiotic lactic acid bacteria in synbiotic-fermented milk production caused a significant increase in diacetyl and acetaldehyde contents compared with both control samples (made with traditional yoghurt culture).
16- Generally, acetaldehyde content gradually decreased in all synbiotic-fermented milk samples as the storage period progressed. While diacetyl content followed by gradual decrease till the end of the storage period (21 days).
17- Adding a 2% inulin or maltodextrin to the yoghurt formula caused a significant increase in apparent viscosity of synbiotic-fermented milk products.
18- Type of starter culture had no significant effect on the viscosity values in all synbiotic-fermented milk products.
19- It could be noticed that, the count of Lb. delbrueckii ssp. bulgaricus were higher in both traditional fermented milk samples made with 2% yoghurt culture (C, T1 and T3) than their counts in all other treatments. Str. thermophilus and Lb. delbrueckii ssp. bulgaricus counts slightly decreased during the first week of storage and then gradually decreased till the end of the storage period.
20- Gradual decrease in probiotic strains counts was observed along the storage period.
21- Addition of 2% inulin and 2% maltodextrin as prebiotic in the manufacture of synbiotic-fermented milk had enhanced the viability of probiotic strains (Lb. helveticus and Lb. acidophilus) along the storage period.
22- It is clear that, the viability of probiotic strains (Lb. helveticus and Lb. acidophilus) in synbiotic-fermented milk made with or without inulin
89
SUMMARY AND CONCLUSION
Reda Mohamed Elkomaily (2022), M.Sc. Fac., Agric., Ain Shams Univ.
as prebiotic were higher during the storage at (4ºC for 21 days) than the recommended minimum levels (106 cfu/ ml or g).
23- Generally, yeast and mould counts could not be detected in all fresh and 3 days refrigerated stored samples. Moreover, yeast and mould counts could be observed and counted after 7days of the storage in treatment samples (C, T1, T4, T6 and T7), and after 14 days in treatments (T2, T4 and T5). These counts slightly increased as the storage period progressed.
24- All fresh and 21 days refrigerated stored synbiotic-fermented samples were free from coliform bacteria.
25- There were slight differences in appearance scores between all treatments and both control samples during the first 7 days of storage period. After that, the appearance score points decreased as the storage period progressed reaching 6 points for some samples and 7 points for some other are for samples at the end of storage period (21 days).
26- The highest of body and texture scores (29) were recorded for synbiotic-fermented milk containing 2% yoghurt culture with 2% maltodextrin, (T2).
27- Control fermented milk made with 2% yoghurt culture (C) reached the least body and texture scores (25) compared with all other samples.
29- The highest remarkable flavour score points (58) were in synbiotic-fermented milk made with 2% Lb. helveticus and 2% maltodextrin (T5), as well as synbiotic-fermented milk containing 2% Lb. acidophilus and 2% maltodextrin, (T8). followed by (T4) synbiotic-fermented milk made with the same culture with adding inulin (56 flavour score points).
90
SUMMARY AND CONCLUSION
Reda Mohamed Elkomaily (2022), M.Sc. Fac., Agric., Ain Shams Univ.
30- Control fermented milk made with 2% yoghurt culture (C) reached the least body & texture scores (25) compared with all other samples.
31- The total score points of both control and all other treatment samples were higher till fresh of the storage period, followed by gradual decrease till the end of storage period.
32- It could be observed that, flavour, body & texture and appearance score points of synbiotic-fermented milk were enhanced by adding the 2% inulin or 2% maltodextrin as prebiotic substance.
CONCLUSIOC
This study provides information on the basic chemical composition, microbiological, rheological, and organolyptic qualities of synbiotic-fermented milk