Reusing Of Wasted Sugar Cooking Liquid From Preserved Cherry Tomato

The market scale of preserved fruit industry has reached 125.883 billion RMB in2018,and the overall growth rate is over 20%.Among them,preserved cherry tomato is one of the main products.As a traditional Chinese food,it is sweet and sour,unique in flavor,and rich in lycopene,polyphenols and other health ingredients,which is popular among the public.However,a large number of thick and turbid sugar cooking liquid will be produced in the processing of preserved cherry tomato,which will be abandoned due to its high viscosity and inability to continue sugar permeation.Taking the preserved fruit factory with an annual output of 500 tons as an example,at least50-150 tons of high viscosity wastewater are produced every year.It not only wastes resources,but also brings heavy burden to the environment.Therefore,the viscosity reduction and reuse of the waste sugar cooking liquid has become one of the key problems to be solved in the preserved fruit industry.Therefore,in this paper,the physical and chemical indexes of the waste sugar cooking liquid in the processing of preserved cherry tomato were analyzed firstly,and then the viscosity forming mechanism of the waste sugar cooking liquid was explored systematically;On the basis of this theory,the technology of viscosity reduction of the waste sugar cooking liquid in the processing of preserved cherry tomato was established and the feasibility of reuse was verified;Finally,the effects of the recycling liquid on the nutritional components,antioxidation,volatile flavor compounds and sensory evaluation of preserved cherry tomato were analyzed.The main results of this paper were as follows:(1)Analysis on the sugar cooking liquid and its viscosity forming mechanism.The effects of pectin,microparticles and their water extracts on the viscosity of sugar cooking liquid were studied.It was found that the viscosity of the sugar cooking liquid mainly depended on the micro particles,and the pectin,protein and other water extracts in the micro particles had an important influence on the viscosity of the sugar cooking liquid.The content of soluble pectin in the supernatant was 0.005‰ and the contribution to viscosity was only 2%.The contribution of microparticles in the waste sugar cooking liquid and its concentrate to the viscosity of the sugar cooking liquid was 33% and 58% respectively,and the removal of microparticles could make the waste sugar cooking liquid become Newtonian fluid.It was found that the contribution of microparticles to the viscosity of the sugar cooking liquid decreased by about 50% after removing the water extract from the microparticles.At the same time,it was found that the waste sugar cooking liquid was rich in pectin(0.005‰),protein(0.17 mg/m L)and free amino acid(29.44 mg/m L),among which free amino acid was mainly glutamic acid(6.42 mg/m L),so it was a good source of amino acid(especially glutamic acid).(2)Establishment of viscosity reduction technology for waste sugar cooking liquid and its feasibility verification for reuse.This paper studied the effect of bentonite and chitosan on viscosity reduction of the waste sugar cooking liquid and the feasibility of its recycling.It was found that the recycling of the waste sugar cooking liquid could be realized by using bentonite or chitosan for viscosity reduction.After the initial screening of viscosity reducing agent and the determination of viscosity reducing conditions,the established viscosity reducing technology of waste sugar cooking liquid was as follows: after the initial screening,the waste sugar cooking liquid was mixed with 0.008% chitosan or 0.12%bentonite,which was settled at 20? for 8 hours,and then filtered.Finally,the recycled sugar cooking liquid was obtained after vacuum concentration at 70?.Through the feasibility study,it was found that the viscosity(50%),turbidity,a* value and volatile odor components(including 1,2-dimethylhydrazine and other bad odor substances)of the recycled sugar cooking liquid were significantly reduced after the viscosity reduction treatment with bentonite or chitosan compared with that of the waste concentrated sugar cooking liquid,and its light transmittance,L* value and sugar permeation rate(the same as that of pure sugar water)were significantly increased,but there was no significant change in soluble solids and p H(P>0.05).At the same time,there was no significant difference between the bentonite and the chitosan treatment group(P>0.05).(3)The effect of the recycled sugar cooking liquid on the quality of preserved cherry tomato.The effects of the recycled sugar cooking liquid on the water soluble and fat soluble nutrients,antioxidant capacity,flavor substances and senses of the preserved cherry tomato were studied.It was found that the quality of the preserved cherry tomato treated by the bentonite was higher than that of the fresh syrup group,the chitosan group and the waste concentrated sugar cooking liquid group,but the quality of the waste concentrated sugar cooking liquid group was the worst.Compared with the preserved cherry tomato in fresh sugar water,the preserved cherry tomato treated with bentonite had higher water soluble nutrients,comprehensive antioxidant capacity,total free amino acid content(3.499%),total volatile flavor substance content(1463.737 ?g/kg),total characteristic volatile substance content(265.349 ?g/kg)and overall sensory evaluation value(77.00),and there was almost no significant difference in fat soluble nutrients.However,the content of water soluble nutrients and total amino acids(3.406%)in the preserved cherry tomato treated with chitosan was higher than that in the fresh sugar water group,but the content of fat soluble nutrients,comprehensive antioxidant capacity,total volatile substances,total characteristic volatile substances of cherry tomato and the overall sensory evaluation value(73.75)were lower.At the same time,there was no significant difference in sensory evaluation,lycopene and other carotenoids and total free amino acids between bentonite group and chitosan group(P>0.05).