FIRMNESS OF CARROT SLICES SUBMERGED IN BRINES: EXPERIMENTAL DATA AND MATHEMATICAL MODEL

The firmness of carrot slices was measured at various temperatures for several concentrations of brines in sodium chloride and lactic acid. A model assuming that textural decay is due to irreversible, pseudo first-order enzyme-catalyzed degradation of the carrot cell wall polysaccharides in the presence of two alternative paths for first order enzyme deactivation was fitted to the aforementioned data sets. The physicochemical and statistical significance of the model and fits were evaluated and discussed. The model is useful for predictions of the textural decay based on reasonable physicochemical considerations in a wide range of brine specifications with practical interest.     

海刺参中微量元素的光谱测定

采用火焰原子吸收光谱法对海刺参中Na、K、Ca、Mg、Fe、Zn、Cu、Mn、Cr、Co10种微量元素含量进行测定分析。采用HNO3＋H2SO4（5：1）混酸作消化液处理样品,各元素在试验范围内,加标回收率和精密度较好,加标回收率为93．8％。106．3％,相对标准偏差（RSD）小于5％。结果表明：海刺参中人体所需的微量元素含量丰富,海刺参中微量元素含量表现为Na〉Ca〉Zn〉K〉Mg〉Fe〉Mn〉Cu〉C0〉Cr。     

高效液相色谱法测定蜜饯中食用合成色素

建立了蜜饯中食用合成色素（柠檬黄、苋菜红、胭脂红、日落黄、亮蓝）的高效液相色谱测定方法，采用C18（4.6mm×200mm，5μm）色谱柱，甲醇和乙酸铵为流动相，流速为1．0mL/min，柱温30℃，梯度洗脱程序为：甲醇＋0．02mol／L乙酸铵，6％～40％甲醇，2．8％／min；40％～60％醇，2．5％／min；60％甲醇，3min；6％甲醇，7min；检测波长：0min～5．5min，430nm；5．51min～8．0min，520nm；8．01min-10．0min，510nm；10．01min-13min，480nm；13．01min-20min，600nm。确定了蜜饯中合成色素的前处理方法。本方法具有灵敏度高，干扰少，色素回收率高的优点。     

NEW METHOD FOR THE DETERMINATION OF YIELD STRESS1

A method is proposed for determining the yield stress of liquid and semi-liquid foods. The described technique makes use of a modified Fisher Autotensiomat apparatus. A yield stress range of from 20 dynes/cm² to about 900 dynes/cm² was covered by products such as condensed milk and tomato paste, respectively. The data were compared with the results obtained with a Ferranti-Shirley cone and plate viscometer, a Chainomatic Beckers balance and a Thomas-Stormer viscosimeter. With the exception of the data from the latter instrument, the results were in good agreement.     

AN ALTERNATIVE METHOD FOR THE DETERMINATION OF DIMETHYL SULPHIDE IN BEER

A method for the determination of dimethyl sulphide (DMS) in beer and for total DMS precursor in malt is described. The DMS was extracted into chloroform and determined by glass capillary gas liquid chromatography (GLC) using a flame ionisation detector (FID) and diethyl ether as an internal standard. Errors arising from the use of ‘head space’ sampling were thereby avoided. The reproducibility of results and the recovery of DMS at the 100 ppb level were satisfactory but less so at levels below 50 ppb. Beers produced in a pilot brewery from malts containing high levels of total DMS precursor were not found to contain correspondingly high levels of DMS.     

AN EMULSION METHOD FOR RAPID DETERMINATION OF FAT IN RAW MEATS

SUMMARY –There is a need for a rapid, safe, precise and practical method for determining fat in raw meats, while insuring sample representativeness. The method developed consists of preparing an emulsion from the meat to be analyzed, and purposely breaking down a portion by heating under alkaline conditions to separate the fat which is measured in graduated Babcock bottles. A good correlation was found between this method taking about 10 min and Salwin's method (Babcock technique) taking about 20–25 min as well as the official ether extraction method taking about 24 hr. The new method seems applicable to samples varying between 4 and 40% fat. It also permits the analysis of large samples of almost any desirable or practical size by analyzing a homogeneous aliquot of a prepared emulsion. It also applies directly to the analysis of meat emulsions prepared in the manufacture of sausage products, for quality control purposes.     

葡萄酒稳定性的电导率测量法

通过测量葡萄酒在加入 Ｋ Ｈ Ｔ晶体前后电导率的系列值。寻求电导率变化与葡萄酒稳定性之间的关系。论证该法在测定葡萄酒稳定性方面的合理性。对不同测量方法的优缺点等问题,本文亦进行了讨论。     

RAPID METHOD FOR THE DETERMINATION OF STEAM-VOLATILE FATTY ACIDS IN RUMEN LIQUOR

A method is described for the rapid separation of steam-volatile fatty acids in rumen liquor by gas-liquid chromatography and automatic titration of the eluted acids. The method consists of a pressure programme for nitrogen gas which allows the separation of acids up to n-valeric in 22 minutes.     

DELINEATION OF PUNCTURE FORCES FOR EXOCARP AND MESOCARP TISSUES IN CUCUMBER FRUIT 1

A puncture test was used to differentiate exocarp (skin) and mesocarp tissues of fresh cucumbers for resistance to penetration. Optimum instrumental test conditions were a punch size of 3.15 mm diameter and crosshead speed of 5 cm/min. The force required to penetrate the exocarp of whole fruit was determined and was deemed to represent a composite of the exocarp and the underlying tissue. By placing 7 mm thick, longitudinal slices skin down on a die plate, failure forces representing the mesocarp and exocarp tissues were determined in fruit ranging from 2.5–5.5 cm diameter. Exocarp force measurements were not influenced by slice thicknesses greater than 1 mm. Mesocarp measurements were lower with thicker slices, and required uniformity of thickness to maximize precision. The exocarp was found to represent about 60% of the composite force required to penetrate whole cucumbers, regardless of fruit size. Toughness of both exocarp and mesocarp increased with fruit size. The relative contributions of exocarp to penetration of seven other fruits varied from 58 to 88%.     

氨基葡萄糖荧光光度分析法的研究

因氨基葡萄糖与吡哆醛缩合反应形成的Schiff碱,可与Zn2+通过氢键结合生成在特定波长激发下具有荧光吸收的Schiff碱金属配合物,在较稀的溶液中,其浓度与荧光强度在一定的范围内呈线性关系.从而建立测定氨基葡萄糖的荧光光度法.衍生条件为:氨基葡萄糖盐酸盐与盐酸吡哆醛于60℃恒温水浴中反应30 min后,加入Zn2+络合30 min.荧光激发波长为386 nm,发射波长为475 nm,灵敏度1,狭缝宽10 nm,线性范围为15 mg/L～65 mg/L,拟合优度99.109％,适用于含氨糖的药品、保健品及其生产制备过程中粗品得率的测定.     

改进荧光法测定食品中微量硒的研究

通过研究分子荧光法测定食品中硒含量的各种影响因素，建立了食品中微量硒的快速测定方法。结果表明采用分子荧光法测定食品中硒含量，适宜用混合酸冷消化后，在电热消化炉上150℃消化5h；生成荧光物质的条件为80℃水浴，pH值在1．5～2.0，反应时间10min。该方法灵敏度高且精确度好，其线性相关系数为r=-0.9994，相对标准偏差为3．48％，回收率99．45％，检测下限为4．5ng／mL。     

紫外光消解-离子选择性电极测定牛奶、酸奶中钾钙

利用紫外光解法处理牛奶、酸奶样品，对光照时间、光照强度、氧化剂配比和用量等条件进行了研究，并对光消解样品和湿法消解样品测定结果进行了对比。结果表明：光照60min左右能将牛奶、酸奶样品消解完全，此方法与湿式消解法处理样品所测结果不存在显著性差异。