The quality of baby spinach as affected by developmental stage as well as postharvest storage conditions

Baby spinach is rich in phytochemicals that provide great benefits to consumers’ health. The study aim was to investigate the effect of the growth harvest stage, postharvest storage duration and temperature on quality of baby spinach leaves. A 3?×?5?×?3 factorial experiment was laid out in a randomised complete block design with four replicates per treatment. The treatments were arranged as follows namely: stage I [28 days after sowing (DAS)], stage II (35 DAS)and stage III (42 DAS), and leaves were kept up to 12 d at three different temperatures – 4, 10 and 20°C. The study demonstrated that the overall appearance and odour were both well maintained in the leaves of baby spinach harvested at stage II. The baby spinach harvested 28 DAS led to higher content of iron [1.13?mg?g^?1 dry weight (DW)], magnesium (14.4?mg?g^?1 DW), and zinc (0.17?mg?g^?1 DW). The highest level of total antioxidant activity (0.43?mg?g^?1 DW) and flavonoids (12?mg?g^?1 DW) after 12 d of storage was observed in baby spinach leaves at stage I when stored at 4°C. Therefore, baby spinach leaves harvested 28 DAS and store at 4°C for 6 d improved shelf life and nutraceutical quality. Thus, early harvest of fresh produced baby spinach harvested in order to attain high phytochemical and mineral content when stored at low temperature (4°C) without exceeding 6 days is recommended.     

No evidence for avoidance of black rat scent by the presumably less competitive Natal multimammate mouse in a choice experiment

In Africa, indigenous multimammate mice (Mastomys natalensis) only appear to live commensally in houses when invasive black rats (Rattus rattus) are absent, yet little is known about the underlying mechanism. Avoidance through smell may cause the absence of M. natalensis from areas occupied by R. rattus, but this hypothesis has not yet been tested. We conducted a Y-maze choice experiment where 15 M. natalensis were offered a choice between corridors containing conspecific scent, R. rattus scent and a control scent. Residence time in the R. rattus corridor was greater than that in the control corridor but equal to that in the M. natalensis corridor, suggesting that multimammate mice do not actively avoid the scent of their invasive competitor.     

Antipredator behaviour of naïve Arctic charr young in the presence of predator odours and conspecific alarm cues

Abstract –  We investigated how Arctic charr young respond behaviourally to olfactory cues from skin-damaged conspecifics, charr-fed pikeperch, and the combination of food-deprived pikeperch and skin-damaged conspecific cues in a two-channel Y-maze fluviarium test arena. Significant antipredator responses were found to skin-damaged conspecifics in three behavioural traits, to charr-fed pikeperch in two traits and to the combination of pikeperch and skin-damaged conspecific cues in all six behaviours investigated. The combination of predator and conspecific cues significantly increased spatial avoidance and cautiousness to approach the source of scent compared with odours from charr-fed predators. The results suggest that damage-released alarm cues exist in charr, and they strengthen the antipredator responses in conspecifics. As the charr used different behaviours and levels of response in the presence of different cues, they seem to have sophisticated skills to distinguish between different odour combinations and be able to adjust their behaviour according to the current predation risk level.     

微生物发酵对罗非鱼下脚料蛋白酶解液脱腥去苦效果比较

以嗜热链球菌(Streptococus thermophilus)、保加利亚乳杆菌(Lactobacillus bulgaricus)和瑞士乳杆菌(L.helveticus)及2种酿酒酵母菌(Saccharomyces cerevisiae)为菌种,对罗非鱼(Oreochromis niloticus)下脚料蛋白酶解液进行发酵,利用感官评定法,比较不同微生物发酵对酶解液脱腥去苦效果.试验结果表明,乳酸菌脱腥效果优于酵母菌,其中以嗜热链球菌脱腥效果最好,其适宜的发酵条件为接种量10%,发酵温度42℃,发酵时间9 h.微生物发酵去苦效果不明显.     

金枪鱼酶解液脱色工艺及其对腥味物质和金属元素的影响

为了研究活性炭对金枪鱼酶解液脱色的最佳条件,本文利用活性炭对金枪鱼暗色肉酶解液进行处理,研究活性炭添加量、pH值、温度(T)和脱色时间(t)对脱色率和蛋白质损失率的影响,采用正交试验对脱色工艺进行优化,同时探究了活性炭脱色工艺对酶解液腥味物质和金属元素含量的影响.结果表明,金枪鱼暗色肉酶解液最佳脱色条件为活性炭添加量3％、pH值3.0、温度70℃、时间1h.该条件下脱色率为89.77％±0.77％,蛋白质损失率为13.47％±0.72％;脱色后酶解液挥发性物质含量降低了85.39％,其中三甲胺、己醛、壬醛等特征腥味物质显著降低;活性炭对Pb的吸附作用较明显,其吸附率为93.2％,而对其他金属元素的吸附率不大.研究表明,经过活性炭处理过的酶解液颜色浅,腥味低,具有一定的应用前景,可为酶解液的进一步利用提供依据.     

The effect of the pH of meat on the boiling test

The effect of the pH on the boiling test was studied in 68 beef and 108 pork muscles. The pH had a significant effect on the sensory scores obtained from the boiling test. The effect was particularly pronounced in the odour of meat. In beef the odour scores remain steady for samples with a pH value under about 6.2 and start to increase rapidly in higher pH values. In pork the increase in scores appears to be linear. The odour observed in high pH meat was described by the judges as abnormal and ammonialike. In the case of meat with a high pH, the results of the boiling test at meat inspection should be interpreted with extreme caution.     

大蒜脱臭工艺参数研究

提出了三种大蒜脱臭工艺,分别建立了大蒜素含量与热处理工艺参数、pH缓冲溶液处理工艺参数变化关系的数学模型,对热、pH缓冲溶液处理工艺进行了正交试验,得到了适宜的脱臭工艺参数:热处理温度80℃,时间50min,缓冲溶液pH为1,浸泡时间90min。     

Impacts of longfin eels (Anguilla dieffenbachii) on the behaviour of common bullies (Gobiomorphus cotidianus) held in captivity

Abstract – Interactions between common bullies (Gobiomorphus cotidianus) and longfin eels (Anguilla dieffenbachii) were studied in aquaria where bullies were subject to one of four treatments – bullies alone (allopatry), bullies and an eel (sympatry), or bullies provided with either visual cues (eel in adjacent compartment of the aquarium) or odour cues (eel in separate upstream aquarium). The total time that bullies were active (movement) and their use of rocks were recorded continuously over 48 h with a video camera. Analysis showed that for movement, there were no significant differences between treatments, but there were diel differences within sympatric treatments with greater activity evident during the night than during the day. In contrast, the use of rocks showed significant differences both between and within treatments; again, the only significant diel difference was in sympatry. Post hoc tests between treatments revealed that there were no differences at night, but during the day, there were differences between allopatry and visual trials, sympatry and visual trials, and sympatry and odour trials. No predation or other aggressive behaviour by eels towards bullies was observed in any trial. It was concluded that the presence of eels affected both bully activity and use of rocks, but this response was not solely due to either visual or odour cues. Changes in movement and the use of rocks appear to require multiple cues, and denial of either visual or odour cues was insufficient to elicit a response.     

通过日粮调控减少猪排泄物中氨与硫化氢的产生与散发量

随着畜牧生产规模的不断扩大和集约化程度的不断提高，畜禽排泄物对环境的污染已受到普遍重视。本文从六方面系统综述了通过日粮调控减少猪排泄物中氨与硫化氢产生与散发量的潜力，其中包括：（1）添加合成氨基酸以降低饲粮蛋白水平；（2）增加饲粮中非淀粉多糖含量；（3）改变饲粮组分以降低排泄物的pH值；（4）调控消化道微生物；（5）添加非营养性添加剂；（6）选用含硫量较低的饲料原料。