Essential oil nanoemulsions: antibacterial activity in contaminated fruit juices

Many human acid tolerant bacterial and fungal pathogens can be transmitted through the consumption of the contaminated fruit juices. We aim to formulate essential oil nanoemulsions (basil, black seed, turmeric, clove & cinnamon), determine their ability to clear contamination by food borne bacterial pathogens from fruit juices. The antibacterial activity of the optimised formulations was tested in the fruit juices against bacterial pathogens causing gastrointestinal tract infections. The minimum bactericidal concentration (MBC) of clove emulsions ranged from 15.6 to 25 μL mL⁻¹. Cinnamon oil emulsion had an MBC ranging between 15 and 31 μL mL⁻¹. At MBC, cinnamon oil emulsions caused a 6log₁₀ decrease in viable counts by 8 h and maintained the sterility of fruit juices for 7 days at ambient temperature. Thus, clove and cinnamon microemulsions can be used as juice additives to control food borne bacterial pathogens and maintain the bacterial sterility of fruit juices.     

离子色谱同时测定果汁中22种糖、糖醇和醇

目的建立积分安培-离子色谱法同时测果汁中22种糖、糖醇和醇定的方法。方法在流速为0.40 mL/min, pH值在6.5～8.6,柱温为30℃条件下,在CarboPacTM MA1(4 mm×250 mm)色谱柱中进行分离。结果 22种组分在测定浓度范围内具有良好的线性关系(r~20.999);除了甲醇外,其他21种组分检出限在0.006～0.203 mg/L之间;在0.50、1.00、5.00 mg/L 3个添加浓度水平下,回收率为75.83%～105.89%,相对标准偏差(RSD)在1.03%～10.39%范围内。结论该方法简便、快速、准确、灵敏,完全适于果汁中22种糖、糖醇和醇的分析测定。     

Combined effect of microwave and ultrasonication treatments on the quality and stability of sugarcane juice during cold storage

The main objective of this study was to investigate the combined effect of microwave (MW) treatment (2450 MHz for 120 s), ultrasonication (US) (24 KHz, 20 °C for 20 min) and combined treatment (MW-US) on the quality and stability of sugarcane juice (SCJ) during 21 days of storage at 4 °C. The effect of the treatments and storage time on physicochemical, bioactive compounds (total phenolic, flavonoids and ascorbic acid content) and microbial analysis of SCJ. No significant (P < 0.05) changes were observed in °Brix, while there was an increase in pH and a decrease in titratable acidity in all treatments. Compared to US and MW, MW-US treatments was more effective in preserving colour attributes, total phenolic and flavonoids contents, ascorbic acid and antioxidant capacities of the SCJ during storage. The results regarding the microbial count indicate that more microbial safety and longer shelf life was achieved by MW-US. MW-US treatment is an effective technology for improving the safety and shelf life of SCJ by minimising quality changes, retaining bioactive compounds and reducing microbial growth during storage.     

榨汁机的结构设计和分析

随着经济的不断发展,国民也越来越注重食品的品质和安全。目前中小食品企业在国内得到越来越多的关注和重视。榨汁机被广泛应用在食品行业,发挥着巨大的作用。汁液获取的三种方法包括机械榨取、理化获取、酶法提取。理化和酶法在使用过程中因会产生物理化学反应,导致其他副作用从而在使用上有极大局限性,机械榨汁由于其无副作用而被企业广泛应用在蔬菜、水果上。基于此,研究了螺旋式连续榨汁机,其核心思想是以压缩体积为基础的一种机械榨取机。首先介绍了榨汁机的设计思路;其次介绍了工作原理;最后展示了榨汁机的机械组成。与传统的榨汁机相比,该方法设计的榨汁机是通过变螺距变径螺杆,从而充分地挤出新鲜果汁,具有十分重要的实际研究意义。     

Coupling osmotic dehydration with heat treatment for green papaya impregnated with blackberry juice solution

Slices (1.5 mm thick) of green papaya were impregnated through osmotic dehydration with a blackberry juice–sucrose solution to produce an intermediate moisture product. The effect of processing temperature (T) and sucrose-added molality (m_sucrose) on mass transfer during the operation was assessed, using a response surface methodology (RSM). The RSM was used to model water loss, sugar and anthocyanin gain during the process. Increasing sucrose molality resulted in increasing water loss and sugar gain, but decreasing anthocyanin gain. Water transfer therefore limits anthocyanin impregnation, but not sucrose incorporation. Afterwards, the impact of heat treatment at high temperatures was analysed, using numerical simulation. The conditions of the combined process, designed to achieve an anthocyanin-rich final product, are low sucrose-added molalities (sucrose molality < 1 mol kg^–1) and high processing temperatures (T > 50 ºC) for osmotic dehydration, coupled with high-temperature, short-time (HTST) heat treatments for product stabilisation.     

The influence of the carrier addition and spray drying temperatures on physicochemical properties of microencapsulated carrot juice powder

The objective of this study was to determinate the influence of carrier addition and spray drying temperatures (160 or 200°C) on physicochemical properties of spray-dried carrot juice powder. As carriers, maltodextrin and gum Arabic in different proportions were used. In powders were determined the following: moisture content, water activity, apparent density, size of particles, colour and carotenoids content. The content of carotenoids in powders prepared from solutions with juice to carrier ratio 2:3 was 324.3–406.6 mg/kg d.m., while in powders with a J:C = 3:2 values ranged from 576.7 to 637.7 mg/kg d.m. The highest content of carotenoids and the most yellow colour were observed in powders with 1:3 gum Arabic to maltodextrin ratio. Powders with the highest amount of gum Arabic have the highest diameter and the lowest water activity. High inlet temperature caused brighter colour of powders, higher dry matter content, lower water activity and apparent density of powders.