液相色谱-串联质谱法测定植物提取物的研究进展

2020年国家实行畜牧业全面减抗、禁抗,寻找到替抗物质对于畜牧业持续稳定发展至关重要。植物提取物因其具有的抗菌、抗氧化等作用成为研究重点,准确测定植物提取物含量至关重要。液相色谱-串联四极杆质谱(liquidchromatographytandemquadrupole-massspectrometry,LC-MS)技术作为近年来前沿的分离分析检测技术被应用到很多行业。本文综述了近几年LC-MS对植物提取物含量的测定研究,以期为植物提取物作为替抗物质应用到畜牧业中,其用法用量的确定提供技术理论支撑,也为植物提取物含量测定标准建立提供参考。     

Improvement of gel properties of mackerel mince by phlorotannin extracts from sporophyll of Undaria pinnatifidai and UVA induced cross-linking

The effects of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different concentration (0, 1.6, 8, and 40 mg/g protein) with and without ultraviolet A (UVA) irradiation treatment on gel properties of mackerel (Scomberomorus niphonius) mince (MM) were investigated. The results indicated that both the breaking force and water-holding capacity (WHC) of the MM gel increased with addition of PTE, and the highest breaking force and WHC were observed with 40 mg/g PTE under UVA irradiation. Low-field nuclear magnetic resonance revealed that free water significantly decreased in this PTE-MM gel as well. UVA irradiation treatment led to reduction of total sulfhydryls and free amines in the PTE-MM gel, indicating more cross-linking between proteins. Electrophoresis results indicated that myosin heavy chains were aggregated in the UVA-treated PTE-MM gel. The microstructure of the UVA-treated PTE-MM gel showed that protein formed more evenly distributed cross-linked structures and was more compact than the untreated control gel. As a conclusion, PTE addition with UVA irradiation is shown to improve gelling properties of mackerel mince.     

蓝莓溃疡病生防链霉菌CX3的抑菌效果及其鉴定

[目的]为了明确从吉林省长白山保护区池西保护站马鞍山云杉人工林林下土壤分离,所获得1株拮抗菌株(编号记为CX3)的生防效果及分类地位。[方法]分别采用平板对峙法和杯碟法测定该菌株活菌及其发酵液的抑菌活性和抑菌谱;并通过形态学、生理生化特征、16S rRNA序列分析等方法研究了其分类地位。[结果]该菌株对13种供试植物病原菌均有抑制作用,抑菌谱广,其中对蓝莓溃疡病菌有极强的抑制作用,抑菌带达25.91 mm,发酵液的抑菌圈直径达31.73 mm;根据其菌株形态、生理生化特性、16S rRNA序列比对,最终鉴定菌株为链霉菌属Streptomyces sp.。[结论]该菌株对蓝莓溃疡病菌有显著的抑制效果,应用开发前景良好,此次是国内首次报道该菌株杀真菌活性。     

3种不同酵母产蓝莓酒风味物质的研究

利用3种不同酵母（T1、FK3-2、LM6）发酵生产蓝莓酒，并对其主发酵期的风味物质进行研究。气相色谱（GC）检测发现，酵母LM6发酵的蓝莓酒后期异丁醇、异戊醇和丁酸乙酯含量较高，分别为2.38 mg/mL、2.13 mg/mL、2.05 mg/mL。高效液相色谱（HPLC）检测发现，菌株LM6发酵的蓝莓酒在28 d时有机酸种类减少，草酸含量增加至3.17 mg/mL，L-苹果酸含量降至0.09 mg/mL、乳酸含量降至9.87 mg/mL，琥珀酸含量降至3.06 mg/mL。电子舌检测中发现FK3-2和T1酵母菌产生的酸味明显且所产风味相似；LM6酵母菌产生的风味较均衡，但鲜味、咸味及丰富性更明显。综合比较发现，LM6酵母菌更适合发酵蓝莓酒。     

蓝莓红豆复合饮料的研究

以蓝莓和红豆为主要原料研制复合果蔬饮料,利用单因素和正交试验,通过感官评价和沉降率优化饮料风味配方和稳定性。采用感官评分对色泽、滋味、气味、组织状态进行评价,得到最佳配方为:蓝莓汁20%、红豆汁15%、蔗糖6%、柠檬酸0.1%。通过离心沉降速率和感官评价指标研究稳定剂对饮料的稳定效果,得到稳定性配方为羧甲基纤维素钠0.05%、黄原胶0.05%、海藻酸钠0.1%。对蓝莓红豆复合饮料的杀菌条件进行初步探索,在70℃杀菌30 min条件下,微生物检测指标和理化指标均符合国家标准。     

Impact of Ozonation Process on the Microbiological Contamination and Antioxidant Capacity of Highbush Blueberry (Vaccinum corymbosum L.) Fruit during Cold Storage

In the studies conducted, the impact of the innovative ozonation procedure on the microbial state and antioxidant potential of highbush blueberry (Vaccinum corymbosum L.) stored under cold storage conditions was assessed. Microbiological analysis was carried out to determine the total number of mesophilic aerobic bacteria and the total number of fungi during the storage experiment. In addition, changes in the flavonoid, anthocyanins, and vitamin C content and the total antioxidant capacity were monitored during the storage. The degree of fruit infection with gray mold and anthracnose was determined. It was found that daily ozonation of fruits with a dose of 15 ppm for 30 min, every 12 h, for 28 days effectively reduced the development of aerobic mesophilic bacteria and fungi. On the last day of storage, symptoms of the infection by gray mold were observed in 27.5% of the control fruit, while the absence of symptoms was observed in case of the ozonated fruit. On the other hand, ozone was ineffective in case of inhibiting the infection by anthracnose. Nevertheless, the ozonation process allowed maintaining a high antioxidant potential of the fruit and substantially reduced losses of flavonoids, anthocyanins, and vitamin C. The utilized procedure has proved to be effective, providing the possibility of extensive use of ozone as a factor allowing sustaining a high commercial and consumption value of the fruit over extended time.     

Antioxidant and antimicrobial activity and potential of heather (Erica spp.) extracts in the control of Listeria monocytogenes

In this work, heather and its flowers were studied regarding their antioxidant and antimicrobial activities. Plants were subjected to ultrasound-assisted methanolic extraction followed by fractionation. A phytochemical characterisation of extracts content in total phenols and flavonoids, and their antioxidant activity was performed. The antimicrobial activity was evaluated through the determination of minimum inhibitory concentration and by bioautography. Following, studies on the antilisterial potential were carried out by: time-kill curves, inhibition of biofilm formation and tolerance of Listeria monocytogenes to adverse conditions. The results evidenced the antioxidant activity in both extracts, as well as, the antimicrobial activity against Gram-positive bacteria. Concerning the evaluation of the antilisterial potential, a bacteriostatic behaviour and inhibition of biofilms formation ability were observed. Listeria monocytogenes showed an increased susceptibility to adverse conditions when preincubated with extracts. Thus, heather and its flowers may be a source of new compounds with antilisterial activity potential.