| Summary: | 博士 === 國立中興大學 === 食品暨應用生物科技學系所 === 100 === The honeybees collected pollen contains all the nutrients, such as proteins, lipids, minerals and vitamins, for brood rearing and bee growth and development. On the other hands, bee pollen is usually used as a folk medicine, and is a good nutritional supplement with beneficial effect of improving health. Tea (Camellia sinensis) pollen is one of the main staples of bee-collected pollen grains in Taiwan. Therefore, we systematically investigated the tea pollen composition and their properties characterized by preparing ethanol (50% EE and 95% EE) and water (CWE and HWE) extracts. Furthermore, the novel metabolite of tea pollen fermentation by Aspergillus niger and lactic acid bacteria (LAB) were analyzed. There are four parts of the present study include (1) the tea pollen pellet size and physicochemical analysis. (2) the physicochemicals, phytochemicals, antioxidant properties and bioactive properties of extracts (CWE, HWE, 50% EE and 95% EE ) were tested. And evaluation of bioactive properties of fermentation by (3) Aspergillus niger BCRC 32073 and (4) LAB (Lactobacillus acidophilus BCRC 10695 and Streptococcus thermophilus BCRC 13869).
The microscopic examination of the pollen shape indicated the pollen particle was an equilateral triangle solid with 40-50 μm side length. The proximate analysis of tea pollen showed that the water activity is low (0.23±0.01). There also are abundant protein (20.03±1.05%), fat (6.86±0.13%) and ash (3.04±0.04%) in tea pollen. The analysis of the four kinds of tea pollen extracts (CWE, HWE, 50% EE and 95% EE) showed that the highest extraction yield (58.5%) was obtained by cold water extraction (CWE). Higher levels of β-carotene, total polyphenolics, and flavonoid were detected in the 95%EE (95% ethanolic extraction) sample. The antioxidant activity showed the ethanolic extracts had higher antioxidant activity than the aqueous extracts. Nine free flavonoid aglycons, gallic acid, catechin, methyl gallate, caffeic acid, P-coumaric acid, ferulic acid, rutin, myricetin, and chlorogenic acid, were identified and quantified. For fermentation, ten percent of pollen or the equal quantity of sample and water (pollen: water = 1:1) inoculating with 2% A. niger BCRC 32073 conidiospores incubated at 30°C had higher titers, higher productivity levels and higher stability of the crude enzymes such as cellulase, xylanase and mannanase. In addition, the results of solid state fermentation (SSF) and submerged fermentation (SmF) showed the pH had a similar tendency value was constant of 3.5-4 for incubation more than 24h. Compare results of SmF with SSF, the former has higher protein and total polyphenol contents in the supernatant or extracts. The total antioxidant activity indicated that culture for 10% of pollen (SmF) had high antioxidant activity than SSF, too. Compare the change of nutrient composition of the supernatant of SmF inoculated beneficial LAB (Lactobacillus acidophilus BCRC 10695 and Streptococcus thermophilus BCRC 13869) to direct the fermentation of pollen by LAB were similarly. And the former has less storage stability than the latter. Lactobacillus acidophilus BCRC 10695 grew to higher cell levels than Streptococcus thermophilus BCRC 13869 in MRS or the pollen of submerged fermentation (SmF). All of outcome of pollen fermentation showed good antioxidant activity, tyrosinase inhibition and angiotensin I converting enzyme (ACE) inhibitory activity. Most of the end products of pollen fermentation by Lactobacillus acidophilus BCRC 10695 display antibacterial activity and the results suggested that it may have potential as a probiotic.
As stated above, the study is demonstrated that the tea pollen is composed of nutritionally valuable substances and antioxidant phytochemicals which may act as a natural source of additives and a potent chemopreventive agent. Further, the two of LAB strains in study grows good when pollen as substrate. The high bioactive conversion products of pollen fermentation were showed the potential applications in commercial are expected with beneficial effects for folk health.
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