国内外包装饮用水法规标准综述

近年来,包装饮用水在发达国家和发展中国家得到了稳步增长。文章综述了国内外包装饮用水的分类及标准,并重点对饮用天然矿泉水的国内外法规异同点进行了分析。对添加矿物质的包装饮用水、饮用天然矿泉水和饮用天然水法规制修订提出建议,以期进一步完善包装饮用水法规。     

尼泊尔发布包装饮用水等质量标准

正4月19日,尼泊尔食品技术和质量控制局发布G/SPS/N/NPL/22通报,发布包装饮用水和矿泉水质量标准,该标准适用于进口或出口包装饮用水和矿泉水,其中包装饮用水是指供人类饮用含天然存在或人为添加的矿物质和二氧化碳(天然矿泉水除外)。标准主要规定安全卫生项目、质量参数、包装和标签等要求。     

超细Ni粉催化剂对长链不饱和脂肪酸加氢性能的研究

在60℃恒温水浴,添加适量乙二醇,碱性条件下,用N2H4.H2O还原Ni2 ,制备出超细镍粉,水洗、离心、干燥后,得到超细镍粉。然后放入高压反应釜中作为加氢催化剂考察反应条件:压力、温度、时间、催化剂/原料比例对不饱和脂肪酸氢化效果的影响。结果显示随着压强、温度的增加,加氢性能变好;而增加催化剂用量,对反应时间影响较小。     

2018年广东省市售275份包装饮用水及天然矿泉水铜绿假单胞菌污染情况分析及检测

目的 对广东地区2018年市售的包装饮用水及天然矿泉水铜绿假单胞菌污染情况进行分析及检测。方法 采用国标《GB 8538-2016食品安全国家标准饮用天然矿泉水检验方法》对实验室2018年抽检的包装饮用水及天然矿泉水进行铜绿假单胞菌项目检测及分析。结果 275份包装饮用水及天然矿泉水中23份样品检出铜绿假单胞菌, 总阳性率为8.36%; 包装饮用水、天然矿泉水的阳性率分别为9.87%、1.92%; 包装饮用水中桶装水的阳性率为100%, 共检出76株阳性菌株, 菌株形态主要为蓝绿色。结论 包装饮用水中铜绿假单胞菌污染状况比天然矿泉水严重, 且集中在桶装包装饮用水中。建议桶装饮用水生产企业采取控制措施, 相关监督部门应加强监督管理。     

五大连池重碳酸矿泉水中二价铁离子稳定方法研究

优选一种或多种五大连池重碳酸矿泉水中亚铁离子的稳定剂。通过在五大连池重碳酸矿泉水中加入柠檬酸、抗坏血酸和富马酸3种稳定剂,考察矿泉水的pH值在6.0～3.0范围内变化时,矿泉水中天然二价铁离子的含量及稳定效果,并综合考察了二氧化碳的填充对矿泉水中价铁离子稳定效果的影响。调节pH≤5.5时,柠檬酸和抗坏血酸对二价铁均有较好的稳定效果,矿泉水中二价铁含量分别大于10mg/L及38mg/L,样品均为透明澄清液。但是,添加抗坏血酸的样品经过长时间保存,颜色变为橙黄色,影响了产品的稳定性。添加富马酸的样品在pH≤4.0时,二价铁离子含量为25mg/L,但是在较短时间内就产生沉淀。柠檬酸是天然矿泉水中二价铁离子的优良稳定剂。二氧化碳对二价铁离子的稳定有一定的影响作用。     

大豆油氢化反应釜数值模拟及工艺优化

以一级大豆油为液相、Pt/C催化剂为固相,釜体为圆柱体,釜体高度为180 mm,内径为120 mm,液面高度为130 mm,利用FIUENT软件对大豆油氢化反应釜进行液固两相数值模拟,发现倾斜式搅拌桨距反应釜底部高度80 mm、桨叶直径40 mm、搅拌速率300 r/min时流体流动及催化剂分布最佳,并以模拟的主要参数制备了高压反应釜。高压反应釜内一级大豆油添加量90.0 g、Pt/C催化剂添加量0.15%(m/m),充入8 MPa的CO2气体,后充入H2保持反应釜内总压为12 MPa,通过优化得出最佳反应温度97℃、反应时间87 min、搅拌速率285 r/min时,氢化后大豆油的碘值为79.50 g I2/100 g,说明模拟准确,为展示大型设备油脂氢化过程提供理论依据。     

乳粉包装顶空气体成分的检测研究

按照包装形式的不同，常见的乳粉包装可分为铝塑复合膜、镀铝复合膜等塑料软包装及金属罐两种；按照包装内气体成分的不同，常见的乳粉包装又可分为充氮包装、气调包装与普通包装三种。充氮包装即向包装内充入一定量的氮气置换原有空气成分，气调包装即向包装内充入氮气与二氧化碳的混合气体，而普通包装即包装内主要是空气，并未做任何抽真空或充气处理。     

不同储存方式对榛子油品质的影响

采用真空、充氮气、添加抗氧化剂3种方式处理榛子油,通过高温强制氧化缩短榛子油试验观察期,以色泽、气味、过氧化值、酸值、羰基值为判断榛子油品质的指标,试验储存榛子油的方法。试验结果表明,经过60℃20 d的强制氧化后,空白、真空、充氮气、充氮气+0.01%TBHQ、0.02%TBHQ 5种方式处理的榛子油样品的色泽均加深,添加0.02%TBHQ样品的气味未变,其他均有哈败气味;随着强制氧化时间的延长,空白、真空、充氮气的榛子油样品的过氧化值、酸值、羰基值均显著升高,充氮气+0.01%TBHQ、0.02%TBHQ处理的榛子油样品的过氧化值、酸值、羰基值升高缓慢,过氧化值升高的幅度最小;添加0.02%TBHQ可以有效地延长榛子油保质期,并保持其感官品质。     

不同包装方式对恒温贮藏柿子脆片品质影响的比较

将柿果进行切片,通过热风-微波联合干燥处理得到柿子脆片。比较六种不同的包装方式:聚乙烯薄膜(Polyethylene,PE)袋、聚酰胺薄膜(Polyamide,PA)袋、PA袋充氮气包装、铝箔复合膜、铝箔复合膜分别添加干燥剂及除氧剂对柿子脆片的保藏效果。将六种不同包装形式的柿子脆片进行恒温保藏试验,每隔7 d对产品的水分含量、色度及质构进行测定并比较,以选择最佳包装方式。同时将柿子脆片暴露于空气中进行破坏性试验确定货架期终点,通过加速货架试验测定L*值的变化预测产品货架期。结果表明:PA袋充氮气包装对柿子脆片的水分含量、色度、硬度和脆度的保持效果最好。破坏性试验确定产品货架期终点L*值为64.56,37℃及47℃保藏时柿子脆片L*值变化预测模型为:y=73.30622e-0.00079x和y=73.05771e-0.0180x,计算得到Q10为2.28,预测25℃贮藏时PA袋充氮气包装的柿子脆片的货架期约为460 d。     

包装饮用水中铜绿假单胞菌检验方法相关问题的探讨

为了研究包装饮用水中铜绿假单胞菌项目的检测,确保铜绿假单胞菌检测的准确性,采用GB8538—2016 《食品安全国家标准饮用天然矿泉水检验方法》中滤膜法测定,探讨了试验过程中水样稀释、滤膜放置、绿脓菌素试验等关键环节对试验结果的影响。结果表明,按照GB 4789.2—2016 《食品安全国家标准食品微生物学检验菌落总数测定》中"样品的稀释"对水样进行递增稀释,能够保证滤膜上生长的菌落数量在适宜范围内,提高计数准确性;其次,滤膜的正确使用以及绿脓菌素试验注意事项,能够有效避免漏检和假阴性结果。     

Ionic milieu of bovine and ovine rumen as affected by diet

Postprandial changes in osmolality, mineral, and volatile fatty acid concentrations in rumen fluid were examined in three cattle fed six widely differing diets. Mineral concentrations varied with diet and postprandial time. However, net changes in postprandial mineral concentrations did not contribute significantly to changes in osmotic pressure. There was an effect of diet and time after feeding on concentrations of volatile fatty acids. Postprandial changes in osmotic pressure were primarily due to changes in concentrations of volatile fatty acids. Magnesium oxide and sodium bicarbonate were fed to sheep to increase the osmotic pressure in rumen fluid. The salt supplement decreased acetate, propionate, heat, and methane production. However, rumen water flux was unaffected by the salt supplementation. Diets which produce hypertonic rumen fluid due to high mineral and/or concentrations of volatile fatty acids may reduce fermentation in rumen.     

不同熬制方法对鸡汤品质的影响

为探讨鸡汤的加工工艺与鸡汤品质之间的关系,以乌黑鸡为原料,分别用砂锅煲汤、高压煮制和常压煮制的方法,在不同煮制时间下加工鸡汤,研究其感官品质、氨基酸态氮含量、总氮含量、pH值和嘌呤核苷酸含量的变化规律.结果表明:相同煮制时间下,砂锅煲汤感官品质最佳,氨基酸态氮和次黄嘌呤核苷酸含量最高,总氮含量与高压煮制时相当;相同煮制方法条件下,煮制时间最长的实验组感官品质最佳、氨基酸态氮含量、总氮含量和次黄嘌呤核苷酸含量最高;不同煮制时间和煮制方法对鸡汤pH值无显著影响.实验得出煮制鸡汤的最佳方法是砂锅煲汤60min.     

干旱和氮用量对烤烟干物质和矿质养分积累的影响

采用盆栽试验研究了干旱和氮用量对烤烟(Nicotiana tabacum L.)干物质积累和矿质养分含量的影响。结果表明,在烤烟的生长发育过程中,干旱胁迫严重影响烟株干物质积累和矿质养分含量,特别是K、Fe、Mn含量对干旱的反应更加敏感,而干旱胁迫不影响不同生育期烤烟矿质养分积累规律。随氮用量增加,烟株干物质积累量显著提高,但烤烟干物质积累对氮用量的反应遵循报酬递减律。在干旱胁迫下增施氮肥可以促进烟株对N、P、K、Mn、B的吸收和积累,降低烟株Ca、Mg、Fe、Cu、Zn含量,而水氮互作对于改善烤烟矿质营养,提高烟株干物质积累量具有显著促进作用。      

Aldehyde contamination of mineral water stored in PET bottles

Aldehyde contaminations that might accompany production of mineral water stored in PET bottles were investigated. One of the production lines of carbonated mineral water in Poland was monitored and PET bottles commonly used for mineral water storage were evaluated. Formaldehyde and acetaldehyde were the most important carbonyls identified in series of bottled water samples, but also propanal, nonanal and glyoxal were found in water samples from the production line. Aldehydes are present everywhere in the environment and can be determined even in pure water at low μg l^-1 levels. It was observed that the concentration of acetaldehyde in water stored in PET bottles depended mainly on the concentration of acetaldehyde in PET material and could reach more than 200 μg l^-1. The temperature, time of storage and concentration of carbon dioxide gas contribute to the migration of aldehydes from bottle walls to mineral water. Higher pressure of the carbonated waters and not CO₂ itself or lower pH of waters seems responsible for higher concentration of acetaldehyde.     

浓香型白酒窖泥质量评价理化指标的筛选

窖池作为浓香型白酒独特的发酵容器,在浓香型白酒生产中具有重要作用,更是浓香型白酒香味物质形成的关键。目前的窖泥质量评价标准主要包括窖龄、感官指标和理化指标,评价体系比较粗放,不能完全、客观地反映窖泥的质量。该实验研究了水分含量、pH值、腐殖质含量、氨基酸态氮含量、总氮含量、有效磷含量和矿物质元素含量等理化指标在不同质量等级窖泥间的分布规律。研究结果发现,pH值、氨基酸态氮和总氮含量能区分不同质量等级的窖泥,真实地反映窖泥的质量状况,可作为窖泥质量的评价指标;水分含量、腐殖质含量、有效磷含量、矿物质元素含量不能区分不同质量等级的窖泥。     

STUDIES ON THE EFFECT OF GERMINATION TIME AND TEMPERATURE ON MALTING OF RICE

The effect of germination conditions on rice malt quality was studied by germinating rice for different periods of time up to 7 days over a range of temperatures (22° to 32°C). Germination time and temperature had a significant effect on rice malt diastatic power, cold and hot water extracts, total reducing sugars, and free alpha amino nitrogen. In general, diastatic power, cold water extract, hot water extract, total reducing sugars and free alpha amino nitrogen, all increased with germination time and temperature. Germination temperatures of 28°C and 30°C were good for the development of diastatic power, cold water extract, hot water extract, total reducing sugars and free alpha amino nitrogen. However germinating at 30°C gave maximum result. The mashing trials with rice malted for 6 days showed a slow and incomplete saccharification, slow filtration rate, and high total available extract in spent grains.     

A comparative study on the physicochemical,cooking and textural properties of fortified rice kernels prepared from raw and parboiled rice

Fortified rice kernels (FRK) are extruded rice-shaped kernels manufactured by blending broken rice flour and vitamin–mineral premix. In this study, four parboiled and three raw rice with intermediate amylose content (20–24%) were processed to manufacture FRK. The system parameters (torque and die pressure), physicochemical properties (length, lightness, water absorption index and water solubility index), cooking properties (cooking time, solid loss, elongation) and textural properties of FRK were analysed and correlated using the Pearson correlation coefficient. The torque and die pressure were 16.76–22.76 Nm and 92.56–136.41 bar, respectively. Compared to raw rice, the parboiled rice showed the highest torque, die pressure and axial expansion in uncooked FRK while longer cooking times, higher elongation ratio and hardness; lesser water absorption ratio and solid loss in cooked FRK. The raw rice FRK showed higher lightness. There was a significant difference between all FRK for water absorption index (1.74–2.52) and water solubility index (2.06–3.53%).     

DIMENSIONLESS CORRELATION FOR ESTIMATING INTERNAL PRESSURE IN THIN-WALLED ALUMINUM CONTAINERS DURING THERMAL PROCESSING

The need for creating container initial pressure, overpressure requirements and maintenance during thermal processing of thin‐walled aluminum containers is briefly discussed. the initial pressure within containers was achieved by injecting liquid nitrogen (LN₂) into the container headspace (0.5, 0.75 and 1 in.) prior to seaming. Experiments were conducted using a computer‐controlled retort with water‐immersion as heating medium, and temperatures ranging from 241 to 261F. Product initial temperature varied from approximately 45 to 135F. Container internal time‐pressure history during processing was monitored using a remote pressure sensor mounted within the container. Using water as model food, a dimensionless correlation that related the maximum cortainer pressure to product headspace, initial temperature and pressure was developed. Increasing retort temperature increased the maximum container internal pressure, while increasing product initial temperature decreased the maximum internal pressure developed within the container processing. the effect of product initial temperature on the maximum internal pressure was attributed to the amount/level of entrapped gasses present. Developed correlation using water predicted the internal pressure for 5% bentonite suspension with marginal errors (2 to 7%). However, the model failed to predict the maximum pressure for oil‐filled containers.     

THE EFFECT OF MALEIC HYDRAZIDE TREATMENT ON NITROGENOUS CONSTITUENTS OF POTATO TUBERS AND ON MINERAL CHANGES IN TUBERS AND SPROUTS

The effect of maleic hydrazide treatment on the contents of total and non-protein nitrogen, protein and minerals was assessed on cortex and pith tissues of two potato varieties (Katahdin and Kennebec) grown at two locations (Long Island and Ithaca, NY). Maleic hydrazide significantly increased (p < 0.01) the total and non-protein nitrogen of cortex tissue but showed no significant effect on protein and mineral contents. Sprouts and bud tissue from Katahdin and Kennebec tubers grown at Ithaca were assessed for mineral composition. In both varieties the amounts of calcium, magnesium, manganese and zinc in sprouts were significantly increased (p < 0.01) by maleic hydrazide treatment. No significant effect of MH on mineral content of bud tissue was observed.     

Effect of simulated reclamation treatments on chemical properties and nitrogen mineralising characteristics of saline and alkali soils from West Pakistan

Nitrogen mineralisation and nitrification during incubation of alkali, saline-alkali, highly saline and moderately saline soils were studied in the laboratory before and after simulated reclamation treatment, in which water plus calcium sulphate were used for the two alkali soils and water alone for the two saline soils. The reclamation processes reduced exchangeable sodium and soluble salts to low levels. Mineral nitrogen accumulation during incubation of original and ‘reclaimed’ soils was accounted for entirely as nitrate. The ‘reclaimed’ soils showed a lag phase in mineral nitrogen accumulation. The moderately saline soil was the only one to show increased mineralisable nitrogen, whilst the alkali and saline-alkali soils, in particular, and the highly saline soil showed reduced mineralisable nitrogen after ‘reclamation’.