SENSORIAL CHARACTERISTICS DURING RIPENING OF THE MURCIA AL VINO GOAT'S MILK CHEESE: THE EFFECT OF THE TYPE OF COAGULANT USED AND THE SIZE OF THE CHEESE

The aim of the present work was to study the sensorial characteristics of Murcia al Vino cheese made with different coagulants (animal rennet and powdered vegetable coagulant obtained from cardoon [Cynara cardunculus]) and of different weights (1 and 3 kg). The cheeses made with rennet showed less odor and taste intensities, a bit clearer color and were harder and grainier, but less creamy than the cheeses made with vegetable coagulant. The big cheeses were characterized by high wine odor, acid odor, wine taste, bitter taste, acid taste, and number, size and distribution of eyes notes. The small cheeses were distinguished by a high overall taste intensity, hardness, overall odor intensity, color, saltiness and graininess. Most of the sensorial characteristics were affected by the ripening time of the cheeses.     

THE EFFECT OF FREEZING AND STORAGE ON THE BACTERIAL FLORA OF PASTEURIZED MILK

SUMMARY: Experiments were designed to determine the effect of freezing and storage on the bacterial population of pasteurized milk. Samples taken on separate occasions sometimes reacted differently to freezing treatment. Significant changes in bacterial numbers occurred after the frozen milk had been stored for 4–5 months at −12°, and this coincided with definite physical changes in the milk. Known numbers of coliaerogenes organisms were added to the pasteurized product in order to study their behaviour when frozen and stored at low temperatures. The counts were significantly lower after storage for 4 months.     

三十烷醇在原生质体冰冻和化冻中对质膜的保护作用

在合适浓度范围的三十烷醇存在下,经冰冻处理的烟草叶肉原生质体化冻后质膜完整率均高于对照。以0.1,0.5和1.0p,p.m三十烷醇对原生质体质膜的保护效果较佳。三十烷醇对甘蔗叶肉原生质体的抗冰冻力有类似效果,使用浓度亦相近。作者认为三十烷醇可能与质膜结合,在维护质膜正常物相和和生理活性的完整性与稳定性中起一定作用。     

脱氮硫杆菌生长特性及其对SRB生长的影响

由土壤中分离得到一株自养型的脱氮硫杆菌(Thiobacillus denitrigioans,硫杆菌属,硫杆菌科,革兰氏阴性化能自养细菌),该菌株的最佳生长pH为7．0。将此菌株与硫酸盐还原菌(Sulfate Reducing Bacteria,SRB,脱硫弧菌属,革兰氏阴性厌氧细菌)混合培养,测定SRB的菌量变化,结果表明,脱氮硫杆菌的生长抑制了硫酸盐还原菌的生长,降低了SRB的腐蚀性的代谢产物硫化物的浓度,腐蚀速率降低,有利于防治SRB引起的微生物腐蚀。     

外源胆固醇对离体原生质体在冰冻—化冻过程中的保护作用

在适宜浓度(0.1～0.4m mol/L)的胆固醇存在下,经冰冻处理的小麦叶肉原生质体在化冻后存活率均高于对照,其中以0.4m mol/L胆固醇对原生质体的保护效果最佳。胆固醇对卷心菜叶肉原生质体的抗冰冻能力具有类似效果。从而表明外源胆固醇与质膜结合后,对稳定质膜结构和保持正常功能具有一定的作用。     

THE EFFECT OF THE TETRACYCLINE COMPOUNDS ON THE STORAGE LIFE AND MICROBIOLOGY OF CHILLED EVISCERATED POULTRY

SUMMARY: Chlortetracycline, oxytetracycline and tetracycline, incorporated at 10 p/m in the ice slush used for cooling, were equally efficient in extending the storage life of eviscerated poultry which was subsequently frozen, thawed and stored at 1°. There was complete correlation between the sensory assessment of 'off'odour and the total numbers of micro-organisms present when these were determined by taking bulk samples of skin from the area under the wing and of the surface tissue of the visceral cavity near the vent. Direct microscopical counts confirmed that the latter area was the most heavily contaminated part of the visceral cavity. Non-pigmented strains of Pseudomonas were the main spoilage organisms of untreated chickens but Achromobacter strains and yeasts were responsible for the spoilage of the chlortetracycline treated chickens. Fluorescence was only observed in spoiled chickens where pigmented strains of Pseudomonas occurred in significant numbers. Spoilage in both control and antibiotic treated poultry was accompanied by a rise in pH in the contaminated muscles, but for various reasons this change could not be used as a direct measure of the extent of the microbial contamination.     

镉、铅及其相互作用对小白菜生理生化特性的影响

本文研究了溶液培养条件下小白菜对镉,铅的吸收积累规律的镉,铅及其相互作用小白菜生理生化特性的影响,结果表明：植物体内镉,铅含量与培养中镉,铅浓度呈正相关性,镉可降低植物对铅的吸收;镉超过一定浓度后,对叶绿素起破坏作用,并促进抗坏血酸分解,使游离脯氨酸累,抑制硝酸还原酶活性。含镉的培养液中,由于铅的加入,加强了镉对植物的毒害作用。     

EVOLUTION OF THE STORAGE EFFECT

The storage effect, a mechanism that promotes species coexistence in temporally variable environments, poses a dilemma to evolutionary ecologists. Ecological studies have demonstrated its importance in natural communities, but evolutionary models have predicted that selection either impedes coexistence or diminishes the storage effect if there is coexistence. Here, we develop a lottery model of competition in which two species experience a trade‐off in competitive ability between two types of years. We use an adaptive evolution framework to determine conditions favoring the evolution of the storage effect. Storage evolves via divergence of relative performance in the two environments under a wide range of biologically realistic conditions. It evolves between two initially identical species (or lineages) when the trade‐off in performance is strong enough. It evolves for species having different initial trade‐offs for both weak and strong trade‐offs. Our simple 2‐species‐2‐environment scenario can be extended to multiple species and environmental conditions. Results indicate that the storage effect should evolve in a broad range of situations that involve a trade‐off in competitive ability among years, and are consistent with empirical observations. The findings show that storage can evolve in a manner and under conditions similar to other types of resource partitioning.     

玉米籽粒贮藏蛋白组成及特性的研究

利用等电聚焦（ＩＥＦ）电泳和不连续醋酸尿素聚丙烯酰胺凝胶电泳（ＮＡＵ－ＰＡＧＥ）对玉米籽粒贮藏蛋白的等电点（ｐＩ）和在Ｆ１中的遗传表现以及贮藏蛋白在胚和胚乳中的分布进行研究,结果表明：（１）玉米籽粒贮藏蛋白的ｐＩ在３．５￣８．４５范围内,可分离的有３９条左右,６０％左右的蛋白质属酸性,ｐＩ分布在３．５０－６．８５范围内,４０％左右属中性偏碱,ｐＩ在６．８５－８．４５范围内。（２）籽粒贮藏蛋白在Ｆ１