Study On Preparation And Product Development Of Mulberry Leaf Powder Enriched With ?-Aminobutyric Acid

At present,there were few studies about ?-aminobutyric acid(GABA)foods and they were in the preliminary stage of research,no mature products yet on the market.Mulberry leaves were increasingly popular because of their nutritional value and medicinal value.The development and application prospects were broad.Researchers had conducted enrichment studies on GABA in mulberry leaves,but the research method wa single,there was no comparison between the differences of the enrichment methods.This topic would compare eight methods of enriching GABA in mulberry leaves(four soaking pretreatment,anaerobic pretreatment,freezing pretreatment,ultrasonic pretreatment),optimizated the enrichment of ?-aminobutyric acid(GABA)in mulberry leaves.At the same time,the changes of enzyme activities were investigated in the enrichment process and of the mechanism of GABA enrichment was analyzed.Further the effects of each enrichment treatment on the antioxidant properties of mulberry leaves,the functional properties of angiotensin converting enzyme(ACE)and ?-glucosidase inhibitory activity werre analyzed,the mulberry leaf powder obtained after the optimized enrichment process was used in steamed bread and cookie products to increase the nutritional quality and optimized the texture performance.The specific results were as follows:The effects of eight methods of enriching GABA in mulberry leaves(soak,anaerobic pretreatment,cold shock,ultrasound)on the GABA,polyphenols,total flavonoid content and antioxidant properties of mulberry leaves were compared.The results showed that the sodium glutamate immersion pretreatment was the best method,the response surface optimization design was used to obtain the optimal enrichment process: the sodium glutamate concentration was 6.22 g/L,the immersion temperature was 25 ?,time was 18 h.The GABA content of fresh mulberry leaves reached 3.77 mg / g by the method,which was6.30 times that of untreated mulberry leaves.During the treatment,The activity of glutamate decarboxylase(GAD)and diamine oxidase(DAO)reached the highest values of12.99,4.69 U/g.There was no significant change in the content of polyphenols,total flavonoids and antioxidant activity in mulberry leaves by the method.The inhibitory activity of mulberry leaves on angiotensin converting enzyme(ACE)and ?-glucosidase was significantly improved to 4.64 and 2.55 times of untreated.The mulberry leaves were dried and crushed into 40-60,80-100,120-140,200-240,and 300-400 mesh which were treated by the optimized treatment.The change ofcomponents in different mulberry leaves were investigated.The results showed that: as the particle size of the powder decreased,the dissolution efficiency was higher,the dissolution rate of 300-400 mesh mulberry leaf powder(1.0 g)on GABA,polyphenol,total flavonoid was 0.49,1.27,0.90 mg/min,respectively 2.04,2.15,1.80 times of 40-60 mesh mulberry leaf powder(1.0 g),At the same time,the water holding capacity,oil holding capacity and expansibility of the powder gradually decreased to 3.51 g/ g,1.38 g/g,2.5%,which was0.63,0.68,0.61 times of 40-60 mesh mulberry leaf powder.The hygroscopicity and angle of repose gradually increased.The hygroscopicity and angle of repose of 300-400 mesh mulberry leaf powder were 17.37% and 1.35 respectively,which were 1.88 and 3.57 times that of 40-60 mesh mulberry leaf powder.Mulberry leaf powder had oxidation resistance to oil and fat,and increased by the decrease of particle size.The oil and fat added with300-400 mesh mulberry leaf powder had a peroxide performance of 0.17% after heating at high temperature(180 ?)for 65 minutes.It was 0.74 times of the added 40-60 mesh mulberry leaf powder.Mulberry leaf buns and cookies were prepared with mulberry leaf powder of different particle sizes,and the effects of adding mulberry leaf powder on the sensory evaluation and texture performance were investigated.The results showed that the sensory evaluation(49.2),hardness(8.170N),elasticity(6.932N)and chewability(23.831mj)of mulberry buns with 200-240 mesh mulberry leaf powder were significantly higher than those without mulberry leaf powder,there was no obvious difference sticky degree between the mulberry leaf bun and which without adding.After 300-400 mesh mulberry leaf powder was added to the cookie,the sensory evaluation was 88.16,which was not significantly different from the cookie without mulberry leaf powder.Adhesion(0.373mj)and hardness(20.191N)were relatively low.This type of cookie was easy to chew and had a low degree of adhesion.