芦笋提取物对冷却肉保鲜效果的研究

采用乙醇提取法从芦笋下脚料中提取抗菌活性物质,用其对冷却肉进行涂膜处理,以感官指标、菌落总数、pH、挥发性盐基氮(TVB-N)的变化为指标,评价芦笋提取物对冷却肉的保鲜效果。结果表明,芦笋提取物对冷却肉具有一定的保鲜效果,与对照组相比,经芦笋提取物涂膜处理后,可以使冷却肉的保质期延长6 d。     

绿芦笋防腐保鲜技术研究

研究了几种保鲜液对绿芦笋防腐保鲜的效果,并初步探讨了应用高吸水性树脂防止保鲜袋内结露的技术。结果表明,4种防腐保鲜液浸蘸笋尖均可明显地抑制贮藏过程中芦笋软腐病的发生,但以双乙酸钠处理效果最好,贮藏至40d、45d,对照已全部发病,而用1.5%双乙酸钠处理的,发病率为0和32%。0.5%中生菌素、1.5%的双乙酸钠和1%氯化钠处理,均有延缓芦笋叶绿素分解的作用。双乙酸钠处理还可以较好地抑制MDA含量的增加并有延缓果胶分解的效果。4种防腐保鲜液处理均不能抑制芦笋纤维素含量的增加。高吸水性树脂在一定时间内具有理想的防结露效果,但适宜使用剂量和包装方式尚需进一步研究。     

外源NO处理对绿芦笋货架期保鲜效果的影响

以硝普钠(SNP)为NO供体,研究了6个浓度NO处理(0.01、0.05、0.1、0.2、0.4、0.6 mmol/L SNP)对格兰德绿芦笋货架期保鲜效果的影响。结果表明:不同浓度的NO处理均可提高绿芦笋货架期的保鲜效果,其中0.2 mmol/L SNP处理的效果最好,该处理释放的NO可延缓绿芦笋的总糖、可滴定酸(TA)和叶绿素含量下降,增强活性氧的清除能力。0.4 mmol/L SNP处理可延缓绿芦笋TA、Vc和叶绿素含量的下降,但其导致清除活性氧的能力下降。0.6 mmol/L SNP处理降低了绿芦笋总糖和Vc含量,而对叶绿素和活性氧清除能力的影响与对照无差异。因此,0.2 mmol/L SNP处理释放的NO可提高绿芦笋货架期的保鲜效果。     

复合壳聚糖涂膜处理对海芦笋保鲜效果的影响

壳聚糖、植酸、氯化钠、桔皮提取液按一定比例配制成复合壳、聚糖保鲜剂,在常温下对海芦笋浸泡涂膜后做贮藏试验。采用正交设计筛选保鲜效果较佳的保鲜剂配方。试验结果表明:与空白对照组相比,经复合壳聚糖涂膜处理的各试验组,明显降低海芦笋贮藏期间的腐烂率和失水率,有效延缓VC和叶绿素的氧化。复合壳聚糖涂膜液的优化配方为壳聚糖1.5%,植酸1.5%,氯化钠0.2%,桔皮提取液10%(质量分数)。经该配方涂膜密封贮藏的海芦笋比未处理的海芦笋保鲜期延长10d以上,可以满足目前物流速率和物流技术对蔬菜保鲜期的要求。     

绿芦笋保鲜技术研究进展

绿芦笋是营养价值极高的药食两用型蔬菜,广受国内外消费者的青睐.目前我国生产的大部分绿芦笋主要用于出口,仅有少部分在国内销售.但室温下,绿芦笋采后呼吸强烈,生理代谢旺盛,不易贮藏,而采用适当的保鲜方法可以有效延长绿芦笋保鲜期.现在关于绿芦笋保鲜方法的研究已有很多,本文对这些方法进行综述.     

芦笋速冻保鲜工艺研究

本文对芦笋的速冻保鲜工艺进行了研究。结果表明：温度85-95℃，时间1.5-3.0min的烫源处理显著地抑制了多酚氧化酶（PPO）和过氧化物酶（POD）的活性，较好地保存了芦笋的感官品质。笋径对烫漂处理的影响最大；速冻芦笋采用真空包装其品质明显优于常压包装，用PE-Ai代比PE代的冻藏效果要好；芦笋的速冻方式以盐渍冻结较送风冻结要佳。     

超声波和气调贮藏对冷却牛肉保鲜效果的影响

本研究采用超声波及气贮等技术处理冷却牛肉，并对保鲜效果进行了评定。评定指标选用了肉色泽、汁液渗出率、pH值、系水力、熟肉率、嫩度、TVB-N值、细菌总数和大肠菌群，结论指出：采用充气包装的实验第7组（混合气体比例为50％CO2＋25％O2＋25％N2）的保鲜效果最为理想，该组冷却肉在0～4℃下达到22d的保存期。原料肉经超声波处理，对肉质嫩度的有所改善。     

不同浓度水杨酸处理对辣椒保鲜效果的影响

用浓度为0.1%、0.2%、0.3%的水杨酸溶液分别对辣椒进行浸泡处理30s,自然晾干后置于室温下袋装贮藏,通过测定失重率、红果率、腐烂率、VC含量和可溶性固形物含量,研究水杨酸对辣椒的保鲜效果。结果表明,经过水杨酸处理后辣椒的失重率、红果率、腐烂率均比对照低,且有效地抑制了VC和可溶性固形物含量的损失。其中浓度为0.2%的水杨酸溶液对辣椒的保鲜效果较好。     

脂氧合酶抑制剂用于芦笋保鲜的研究

以测量贮藏期间氧气、二氧化碳相对含量的变化和乙烯发生量来评价脂氧合酶抑制剂用于芦笋保鲜的效果。实验结果表明,用脂氧合酶抑制剂混合液(含TBHQ0.05%、茶多酚0.1%、Vc0.02%)处理密封袋装的芦笋,氧气、二氧化碳百分含量变化幅度很小,暗示了其采后呼吸的减弱,而乙烯逸出量仅为空白样的3/4,芦笋可保持良好外观5周以上。这些现象证实了抑制剂可以有效地延缓芦笋衰老,从而使其货架期得以延长。     

芦笋嫩茎采后生理和品质变化及保鲜技术

介绍了芦笋嫩茎采后的生理和品质变化以及嫩茎预冷、冷藏、人工调节气体 (CA)贮藏、自发气调 (MA)贮藏、γ 辐照处理和其他贮藏保鲜技术研究进展。     

Extending the shelf-life of asparagus spears with a compressed mix of argon and xenon gases

Noble gases that form clathrate hydrates when dissolved into water and restrict water molecule activity can prolong the shelf life of fruits and vegetables. Physiological and physical aspects of asparagus spears treated with mixtures of compressed (1.1 MPa absolute) argon (Ar) and xenon (Xe) (2:9 in partial pressure) were compared with controls under normal preservation in modified atmosphere packaging (5% O₂ and 5% CO₂) and cold storage (4 °C). The bract opening and respiration rates of asparagus spears were reduced slightly after the Ar-Xe treatment. A clear reduction between the compressed air and compressed mixture of Ar and Xe was only observed on the 6th and 15th days of storage for the bract opening rate and the 15th day of storage for the respiration rate. The climacteric peak was comparatively inconspicuous. The increase of crude fiber was reduced and both vitamin C and chlorophyll preserved. Based on comprehensive evaluation, asparagus spears treated for 24 h with mixtures of Ar and Xe could be kept in good quality for 12 days at 4 °C.     

Impact of PEF treatment on quality parameters of white asparagus (Asparagus officinalis L.)

Pulsed Electric Field (PEF) application on white asparagus (Asparagus officinalis L.) was exercised to examine influence of electroporation on spear characteristics as composition and texture. PEF treated spears showed altered storage behaviour, which was noticed by increased mass transfer as higher water loss as well as the decrease of the Maillard reaction substrate glucose. Cell disintegration measurement revealed significant influence of electric field orientation on electroporation. Since the anisotropy of asparagus tissue, PEF processing in longitudinal direction of the spear axis resulted in 9.06% higher cell membrane permeabilization than treatment in transverse direction. Furthermore, total solids inclusive lignin content were measured to obtain textural improvements of asparagus spears. It could be shown that dry weight as well as the amount of lignin was reduced after PEF implementation. Lignin degradation (− 2.4%) might be attributed to the PEF induced interference of electrostatic dipole–dipole interactions between lignin and cellulose and subsequent delignification.

Industrial relevance

Since three decades the technology of Pulsed Electric Fields (PEF) received considerable relevance in food — and bioengineering as well as in medicine. Besides the use of PEF to inactivate microorganisms main focus is put on the disintegration of biological cell material to enhance mass transfer in drying or extraction processes. Although the effects of PEF on various plant cell materials are well studied only scarce knowledge exists concerning the impact of PEF on white asparagus. In the study undertaken the PEF-induced changes in asparagus texture and composition were examined. The investigations shall help to reduce unfavored intra- and extracellular components to gain food safety as well as softer spear texture.     

复合芦笋汁加工工艺研究

以芦笋弃料(笋皮)为原料,经破碎、榨汁后,出汁率为52.5%,含可溶性固形物3.8%。将25%～40%的芦笋原汁与10%～25%苹果原汁复合时,可较好地掩盖芦笋皮带入的苦味,而芦笋特有的清香味不受影响。芦笋原汁35%、苹果原汁15%、白砂糖3%、柠檬酸0.15%、阿斯巴甜0.03%与清水组成复合芦笋汁具有浓郁的芦笋清香味,略带苹果香味,甜酸适口。     

Cytological and compositional evaluation of white asparagus spears as a function of variety,thickness, portion and storage conditions

An evaluation was made of the degree of toughening of asparagus during its storage through a study of the morphological and cellular differences of the xylem vascular bundles as a function of the variety, thickness and portion of the asparagus spear. Light microscopic examinations were carried out to determine the thickness of the cell wall to quantify the extent of the toughening. At the same time a study was made of the fractions of dietary fibre of the asparagus spear by means of chemical extraction techniques. Statistically significant differences were observed in both methods between varieties, thicknesses and portions of the asparagus spear. Different factors such as variety, degree of maturing, portion of spear, moment of harvesting, and type and time of storage have an influence on the toughening of white asparagus that should be taken into account in order to standardise its quality. © 2000 Society of Chemical Industry     

Effects of heat treatment on atmospheric composition and color of peeled white asparagus in modified atmosphere packaging

Freshly harvested spears of white asparagus were subjected or not to heat treatment by immersion in a hot water bath at 55 °C for 3 min, then left unpeeled or were peeled before wrapping in 16 µm stretch film and stored at 3 °C for 6 days. During storage, the atmosphere within the packages was sampled for O₂, CO₂ and C₂H₄ determination, while spear fresh weight, color and anthocyanin content at the 3 cm apical peel segments were determined before and after storage. The results showed that CO₂ concentration in packages of white asparagus spears was not greatly influenced by peeling or heat treatment. On the other hand, a higher package O₂ depletion of treated (peeled or heated) spears was observed. Peeling also resulted in an increase of ethylene peak concentration, indicating wound-induced ethylene production, which was suppressed by heat treatment. The initial color of the whole spear was retained, while the appearance of a violet coloration on the spear tip was prevented by heat treatment in both unpeeled and peeled spears.Industrial relevancePeeled white asparagus has drawn the attention of industry as a novel lightly processed product. The combination of heat treatment with modified atmosphere packaging (MAP) could be used to improve the storage life of this product. Moreover, both peeling and heat treatment cause changes in ethylene production and respiration rate of asparagus spears and this information could be useful for development of novel application to MAP design for lightly processed (peeled) white asparagus.     

VARIOUS BLANCHING TREATMENTS EFFECT FINAL TEXTURE AND TOTAL FIBER CONTENT OF PEELED PROCESSED ASPARAGUS

The effect of peeling and three different methods of blanching on the texture of white asparagus was studied. Texture was measured in terms of maximum shear force and cutting energy, and as total fiber content. Manual peeling reduced the required cutting force in the middle and basal sections of the spear; fiber content diminished due to the elimination of the outer, most heavily lignified, layers of stalk. Results suggest that blanching by progressive immersion in hot water may be a feasible method of maintaining uniformity in asparagus texture. Blanching in hot water vapor seems to provide for less tough spears.     

Peroxidase Fractions from Asparagus of Varying Heat Stabilities

Chromatofocusing was used to fractionate asparagus peroxidases. Basic isozymes of pI greater than 9.0 predominated throughout the spear. In addition, a more acidic peroxidase fraction is found in the asparagus spear tip. The basic and acidic fractions were similar in heat stability, but the acidic fraction reactivated readily after heating at 70°C.     

Nutritional evaluation of mineral content changes in fresh green asparagus as a function of the spear portions

Changes in the copper, iron, zinc, manganese, nickel, chromium, calcium, magnesium, sodium, potassium and phosphorus content of fresh green asparagus (Asparagus officinalis L) according to the portion of spear considered and differences existing between varieties (Mary‐Washington and UC‐150) and thicknesses (<11 and 14 mm) asparagus were investigated. Using a three‐factors (portions, varieties and thicknesses) ANOVA and the Scheffé multiple range test (P < 0.05), statistically significant differences (P < 0.001), between the 10 portions in which the spears was cut, were observed for the 11 mineral elements investigated and the more apical portions presented, except for sodium, a higher mineral content which showed a generalised decrease when the portions were furthest away from the asparagus tip. By multivariate study of cluster between portions, the 0 apical portion (asparagus tip) was grouped separately to the rest of portions of the spear. These changes between portions involved a greater nutritional value of the apical zone spear in basis to the nutritional profile established for the mineral content. The diminishing distribution of the mineral concentration throughout the spear was also observed in the varieties and thicknesses of fresh green asparagus investigated which showed significant differences in this mineral content without these changes involved any nutritional significance since the mineral RDAs supplied were similar. Nutrient density percentages of the total fresh green asparagus are much higher than 100% for all the elements studied, except for sodium, and therefore, if the fresh green asparagus is consumed in sufficient quantities, contributes substantially to the intake of these mineral elements. © 1999 Society of Chemical Industry     

ETHYLENE INDUCED ISOPEROXIDASE CHANGES DURING FIBER FORMATION IN POSTHARVEST ASPARAGUS

Excision of asparagus spears triggered increased peroxidase activity and a shift in isozyme species. Changes in peroxidase occurred within 8 hr after harvest at the cut end of the spear and progressed to the tip end after 24 hr storage at 20 °C and 85% relative humidity. Isozyme changes were accelerated by exogenous ethylene gas. Ethylene production by cut spears and rate of spear toughening were greatest when spears were cut above ground. It is suggested that wound ethylene triggers a shift in peroxidase isozymes which participate in lignin biosynthesis and results in spear toughening after harvest.     

臭氧水处理对绿芦笋贮藏品质的影响

研究了采用0.3 mg/L臭氧水处理的绿芦笋在8℃冷藏期间叶绿素、抗坏血酸、总酸度、水分含量和感官质量的变化。结果表明:处理后绿芦笋中叶绿素、抗坏血酸含量的下降速度低于对照,失重率降低,感官品质明显优于对照组,处理15 min组可延长贮藏期限达到15 d左右,但臭氧水处理对芦笋中总酸度影响不明显。