| Bitter gourd is a well-known vegetables and have health functions, in order to understand the nutritional value of stem, leaf and fruit of bitter gourd and pioneering applications. Firstly, this article was measured the major nutrients content in stems, leaves and fruit of five bitter gourd varieties, and dominant species selected for the preparation of bitter gourd powder by gray relational evaluation. Secondly, compared the impact of hot air and far-infrared drying temperatures on the quality of bitter gourd powder, determined the preparation process of bitter gourd powder. Finally, with the twin-screw extrusion technology developed a resistant foam and linger, strong aroma, good taste and has a certain health function of substitute tea---- the extrusion bitter gourd particle tea. Throughout the test includes the following three aspects:(1) In this study, the five spring bitter gourd varieties (Chun-tai,239-1, Chun-hua, 97x222,73-1×249-1) of changsha local representative as raw materials, were measured and compared the content of moisture, Vc, crude fiber, ash, polysaccharides, flavonoids and saponins in stems, leaves, fruit of each bitter gourd variety. The results showed that there were significant differences of moisture content, crude fiber, ash, polysaccharides and flavonoids in bitter gourd stems, leaves, fruits, Vc and saponins content was not significantly different; Crude fiber content (35.85%) is the highest in bitter gourd stem; ash (18.60%), flavonoids content (1.93%) and saponin content (1.54%) is the highest in bitter gourd leaf; moisture (94.81%), Vc content (65.30 mg·100g-1) and polysaccharide content (29.61%) is the highest in bitter gourd fruit. Nutritional ingredients of different bitter gourd were also different, Chun-hua with the highest content of Vc, polysaccharides and saponins, Chun-tai with the highest moisture and flavonoid content; 97 x 222 with highest content of crude fiber, 73-1×249-1 combination of highest ash content. Bitter fruits of different varieties were evaluated by gray correlation, correlation of size was Chun-hua (0.8624)> 97 × 222 (0.7271)> 73-1×249-1 (0.7121)> 239-1 (0.7117)> Chun-tai (0.6594), indicating that the variety of bitter gourd named Chun-hua (Green and White sudden aneurysm) integrated the best quality and high nutritional value; Chun-tai’s comprehensive quality worst. Meanwhile, compared with the bitter melon fruit, bitter gourd stems and leaves are also rich in nutrients, can change waste into treasure, to utilization.(2) In this study, fresh bitter gourd as raw materials,with drying methods of hot air and far-infrared under different temperature (40℃,50℃,60℃,70℃,80℃),were used to produce the bitter gourd powder. What’s more, quality indicators, including drying characteristics, color parameters, content and retention rate of Vc, momordicoside content, were compared. Hot-air drying is more effective compared to far-infrared drying at the same temperature, and the energy loss is relatively save 5.6% to 20%. In summary, hot air drying under 60℃ achieve a perfect performance with a satisfactory color as well as in a short drying time(10h) with a less energy loss(31.8 kw-h). For the obtained powder samples, the retention rate of Vc reached as high as 69.31% with a content of 63.42(mg·100g-1) and the content of momordicoside attended a good value of 1.74%.(3) Bitter gourd powder and hydroxypropyl distarch phosphates (9:1) as raw material, twin-screw extruder technology was used to prepare bitter gourd particle tea, tea brew dissolution rate and flavonoid content as an index, and screened extrusion parameters (plus water flow, cavity temperature, screw speed) range through single factor experiment, then extrusion parameter optimization by response surface method, in response to sensory evaluation value, to get the best conditions for the extrusion process parameters:water flow 35%, chamber temperature 98℃, screw speed 197r/min. Bitter gourd particle tea prepared in this condition, has the highest sensory score (98 points), and the brew dissolution rate of 19.8%, tea flavonoids content were up to 0.077 mg/mL. Further compared with commercial bitter gourd sheet tea:found that the sensory score, the dissolution rate and tea flavonoids of bitter gourd particle tea were higher than commercial bitter gourd sheet tea. Twin screw extrusion prepare bitter gourd particles tea, for the study of new bitter gourd products open up a new direction.(4) Stems and leaves of bitter gourd be utilized to powder added in bitter gourd particle tea formulations after hot air drying at 60℃, the formulations of bitter gourd particle tea with bitter gourd powder, bitter gourd stems and leaves powder and hydroxypropyl distarch phosphates for 8:1:1, the optimal process parameters has been used to prepare bitter gourd particle tea. Brew dissolution rate, tea flavonoids content and sensory evaluation for evaluation, compared the quality with bitter gourd particle tea without stems and leaves powder. By comparison found that the bitter gourd particle tea added stems and leaves powder has a high sensory score (93 points), and the flavonoid content (0.086 mg/mL) was higher than bitter gourd particle tea without stems and leaves powder. The test for bitter gourd stems and leaves recycling resources, comprehensive utilization of bitter gourd propose new ideas. |
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