| As a medicinal food,ginger is rich in nutrition,pharmacological effects and unique flavour.China is a major producer of ginger.However,the processing of ginger has been dominated by simple processing with low added value.The bioactive substances cannot be retained in this way.In addition,fresh ginger has a high moisture content.Which contributed to the spoilage of fresh ginger during storage and transport.Therefore,new products need to be developed to make full use of ginger resource rationally.Spray drying is the common drying method.Nevertheless,there are fewer reports of ginger being dried using spray drying.Thus,it is important to combine spray drying with the preparation of ginger powder and its related products.In this paper,ginger was used as raw material.The ginger juice formulation was optimized to enhance the extraction of bioactive substances from ginger.Meanwhile,the parameters of the spray drying process have been optimized to increase the productivity of the ginger powder.The active ingredients of ginger juice have been assayed after thermal treatment.It is modified by agglomeration using fluid bed granulation technology to improve the properties of ginger powder.Finally,ginger powder is applied to milk tea to develop a unique taste and flavour of ginger milk tea.The specific research results are as follows:(1)After single factor and orthogonal experiments,the optimized process for the preparation of ginger juice is as follows: blanching time of 2 min;solid-liquid ratio of 1:3;and juice extraction time of 4 min.After optimization,the content of 6-gingerol in ginger juice reached 9.85 ± 0.06 mg/g DM.The spray drying conditions were optimized by the combination of single factor and response surface methodology.The production of ginger powder was maximized in this process.The optimized spray drying parameters were as follows: inlet temperature of 171.59 °C,suction rate of 90.52%,feed rate of 5.74 m L/min,air flow control between 500-650 L/h.The validation experiment obtained a ginger powder yield of 50.12 ± 0.83%,which is close to the predicted value.(2)Three types of ginger powders were obtained and characterized by adding maltodextrin to ginger juice in different proportions of 7%,13% and 19%.These ginger powders were named M1,M2 and M3 respectively.The moisture content of three ginger powder was less than 5%.The moisture activity was less than 0.3.The moisture absorption was greater than 19%.The wetting time was higher than 170 s.The solubility was greater than 92%.The final content of 6-gingerol in M2 reached a highest level of 0.47 ± 0.01 mg/g.The three ginger powders exhibit strong cohesiveness and poor fluidity.The average particle size of the three ginger powders were less than 20 μm.And the three ginger powders have a Carr Index(CI)greater than 35% and a Hausner Ratio(HR)was greater than 1.4.The three ginger powders were similar in color.The color was pale yellow after brewing.The flavor showed sweet and spicy with a strong ginger flavor.After 30 minutes the aqueous ginger powder solution remains stable.In particular,M2 showed the best overall stability.Thus,M2 was used as a sample for a follow-up study.It was found that the6-gingerol content was barely affected by the heat treatment when the ginger juice was subjected to different times(1,2,3,4 and 5h)of heat treatment(70,80 and 90°C).(3)The agglomeration of spray-dried ginger powder using different binders revealed that agglomeration reduced the moisture content and water activity as well as the hygroscopicity of ginger powder and improved the wettability,with the wetting time of glucose agglomerated ginger powder(GA)shortened to 36.33±5.69 s.The agglomeration resulted in a significant increase in the fluidity(CI<20 %)and a significant decrease in the adhesion(HR<1.5)of ginger powder,with GA having a CI<15% and HR<1.2.The mean particle size of the agglomerated ginger powders increased significantly,with the largest agglomeration of xanthan gum reaching 477 ± 10.56 μm.The agglomeration formed porous,rough and irregular ginger powder particles,which changed the chemical structure of the ginger powders.All ginger powders are amorphous powders and agglomeration reduces the crystallinity.Agglomeration improves the floating of the ginger powder after brewing and prolongs the stabilisation time,especially for GA(ΔBS< 2%).Therefore,agglomeration improves the performance of spray-dried ginger powders and glucose is the most suitable binder for agglomeration.(4)Single-factor and orthogonal experiments were carried out to determine the optimal milk tea recipe using sensory scores as indicators: sugar,milk powder,tea powder and ginger powder were added at 6%,8%,0.6% and 4% respectively.The recipe milk tea displayed a soft color.And the recipe milk tea showed a sweet and spicy blend with intense milk,tea and ginger aromas.The sensory score for milk tea was 85.67±1.36.Effect of the presence of ginger powder on the stability and aroma composition of milk tea was analyzed.It was found that the addition of ginger powder improved the floating of the milk tea.In addition,the presence of ginger powder reduced the gelation of the milk tea thereby enhancing its stability.The variety of aromatic components of milk tea became richer by adding ginger powder.The overall stability of the formula milk tea remains fairly similar to commercial milk teas.However,the aroma composition of the different milk teas varied considerably.The milk tea recipe shows 44 aromatic components.The aroma of the formula milk tea was mainly derived from olefins.The aroma of commercial milk teas and those with ginger powder was mainly derived from alcohols.Meanwhile,the number of aroma components in milk tea has increased from 24 to 36 owing to the addition of ginger powder.Therefore,the ginger milk tea developed meets the commercially available standard.This paper provides guidance for the development of milk tea. |
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