Geographical Origin Identification And Quality Comparison Of Chinese Goji Berry By ~1H NMR Techniques

Goji berry(Lycium barb arum L.)has been widely using as a traditional medicine and health care product for centuries,and it is also a plant with high economic value.The fruits of goji berry present different colors,and red and black goji berries are two typical varieties.The consumption of goji berry is quite popular in consumers due to its many biofunctions such as promoting immunity,anti-aging and scavenging free radicals.The price of goji gerries is closely related to their geographical origin and variety category,therefore there is an urgent need for a fast and accurate analytical method for the geographical identification and nutritional analysis of goji berry,which is conducive to the origin identification and brand protection of high-quality goji berries.In addition,the analysis of the nutritional components of goji berry will help to understand the edible value and the medical uses of goji berry.As a mature detection technology,nuclear magnetic resonance(NMR)has been widely used in food research.It provides many advantages such as non-destructive detection,simultaneous detection,good reproducibility and rapidity over other detection methods such as near infrared spectroscopy and high performance liquid chromatography.Combing with univariate and multivariate statistical analyses based pattern recognition will provide novel methodology for the origin identification and nutritional composition analysis of various foods.In this thesis,NMR-based technique combined with multivariate statistical analysis was applied for the geographical origin of the red goji berry(Lycium barbarum)and black goji berry(Lycium ruthenicum).In the first part,60 components were identified and quantified from four categories of Ningxia red goji berries,including lycium barbarum polysaccharides,betaine,citric acid and other components.The different multivariate statistical analyses including PCA,PLS-DA and OPLS-DA were used to establish the models for the classification of origin and obtaining the intra-and inter-groups compositional differences of different-origin goji berries.Finally,a four-dimensional volcano map was constructed to screen out the geographical markers of each category of red goji berry.In the second part,NMR techniques were used to analyze black goji berries from Qinghai and Tibet.Combing 1D and 2D NMR spectra,57 components were identified and quantified from the black goji berries,including lycium barbarum polysaccharides,cinnamic acid and morning glory pigment and other substances.A classification model of production area of the black goji berries was established,and the characteristic markers were screened out for the specific geographical origin.Finally,the quantitative results of red and black goji berries were compared to obtain the potential difference in nutritional value and the prospect of medical value.At the first time,NMR technique combined with multivariate statistical analysis was applied to conduct origin identification and quantitative analysis on Chinese goji berry.The results will provide a theoretical basis for the classification and nutritional value of Chinese goji berry and a meaningful reference for the establishment of quality control system and monitoring and adulteration identification of Ningxia goji berry.