Citation
Abdul Ghani Zidan, Dina
(2019)
Saccharum officinarum L. by-products (pith and rind) as potential source of prebiotic in vitro.
Masters thesis, Universiti Putra Malaysia.
Abstract
Agricultural residues are normally present in massive amounts, and their costs of
disposal are very high. Notwithstanding their rich nutritional values, the wastes remain
under-utilized commercially due to inadequate study. Sugarcane (Saccharum
officinarum L.) by-products; rind (SR) and pith (SP) promote well-being, probably as
natural ingredients for functional and medical food industry. The aims of the research
were to evaluate the health benefits and functional properties of Sugarcane by-products
(SB) through the estimation of their chemical compositions, antioxidant capacities
(DPPH and FRAP assays) and phytochemical compounds (phenolic and flavonoids) as
well as to evaluate the prebiotic properties of enzymatically produced
xylooligosaccharide (XOS) including; non-digestibility experiment using α-amylase and
artificial gastric acid juice and selective fermentation using pure cultures namely:
Lactobacillus casei Shirota (LcS), Bifidobacterium animals subsp. Lactis and
Escherichia coli. Both SR and SP were found to have high total dietary fiber contents
(58.91% to 69.10% DW, respectively), with high proportion of insoluble dietary fiber.
The available carbohydrate content (AC) in SR (31.72% ± 0.47 DW) was significantly
(p<0.05) higher compared to SP (23.07% ± 0.45 DW). The high content of dietary fiber
and available carbohydrate are characteristics that made SB as fermentable potential
food. The result of antioxidant activities revealed that SR had significantly higher radical
scavenging activity (62 % ± 1.06) than SP (51.32% ± 1.18) using the DPPH assay and
higher reducing power activity (6.98 ± 0.30 mg FeSO4/100g DW), than SP (2.77 ± 0.32
mg FeSO4/100g DW) using the FRAP assay. In addition, SB showed high total phenolic
contents (SR= 469 ± 3.25; SP= 273 ± 4.27 mg GA/100g), and total flavonoids contents
(SR= 269 ± 16.80; SP= 169 ± 4.36 mg QE /100g), being significantly higher in SR
(p<0.05). This study showed that SB contained XOS known as prebiotic agent. In the present study, XOS mixture was successfully produced from SR and SP (XOS-SR and
XOS-SP) respectively. XOS-SR was composed of 1.78 ± 1.01 and 1.62 ± 0.02 mg/mL
xylobiose and xylotriose respectively, while XOS-SP was composed of 1.75 ± 0.05, 1.04
± 0.06 and 0.19 ± 0.02 mg/mL xylobiose, xylotetrose and xylotriose, respectively. Based
on the non-digestibility test, around 84 to 88.24% of XOS consumed would reach the
colon and then be utilized by the probiotic as small amounts of the saccharides were
hydrolyzed by α-amylase (8.29 to 12.87%) and by gastric juice (3.47 to 4.07%). The
fermentation test demonstrated that XOS derived from SB is a potential prebiotic
ingredient due to the evidence that probiotic bacteria (LcS and Bifidobacterium)
increased significantly (p<0.05), while E. coli growth was suppressed in vitro condition.
In addition, the probiotic bacteria supplemented with XOS produced high amount of
SCFAs, known as fermentation end products during the fermentation, indicating the
ability of tested bacteria to utilize XOS-SR and XOS-SP, where acetic acid was the
predominant end product, followed by propionic acid and lactic acid. In conclusion,
sugarcane by-products are potential ingredients for development of functional foods.
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