Effect of Fruit Properties on Pomegranate Bruising

Pomegranate fruit quality is adversely affected by bruise damage. Bruises are formed by a variety of static loads and dynamic impacts on the fruit when it strikes any other object during handling, sorting, packaging, or transportation. In order to be able to reduce this damage, it is necessary to ascertain the influence of fruit properties on bruise susceptibility. An experimental study was performed with varying storage time, temperature, and impact region. In these experiments, pomegranates were dropped from three heights onto a flat aluminum surface. Significant effects on bruising in relation to storage time, temperature, impact region, and their interactions were found (p < 0.05). It was concluded that higher fruit temperature, firmness, and peel thickness reduced bruise damage to the pomegranate fruit. Moreover, storage time and increased radius of curvature increased the bruise volume and bruise area, respectively.     

The effect of impact and fruit properties on the bruising of peach

Peach fruit quality is adversely affected by bruise damage. In order to reduce this damage, it is necessary to know the influence of fruit properties on bruise susceptibility. Two bruise prediction models were constructed for the damage susceptibility of peach fruit (measured by bruise volume) using multiple linear regression analyses. In the first model, peak contact force and three fruit properties (acoustic stiffness, fruit temperature and radius of curvature) were used as independent variables. In the second model, peak contact force was replaced by the impact energy. Peaches were subjected to dynamic loading by means of a pendulum at three levels of impact. Significant effects of acoustic stiffness, temperature and the radius of curvature and some interactions on bruising were obtained at 5% probability level with the coefficient of determination of 0.97 and 0.98 for models 1 and 2, respectively. It was concluded that lowering the temperature and increasing the radius of curvature and acoustic stiffness will reduce the bruise damage of the peach fruit.     

LOW-LEVEL BRUISING OF STORED APPLES DUE TO QUASISTATIC LOADING UP TO CONSTANT COMPRESSION STRAIN

Gold Delicious and Spartan apples were compressed between two plates and the bruise-spot volume was subsequently inspected. Fruits were loaded and unloaded at a strain of about 8%. Tests were performed from harvest to the end of storage under: normal conditions (cold storage at 2C for Spartan and OC for Golden Delicious) and modified conditions (the same temperatures but the Biofresh solution was applied to the fruits before being cooled in storage). The contact Hertz theory can be used to describe the compression curve up to the bioyield point. The parameter BMR (bioyield stress to apparent modulus of elasticity ratio) was used for classification of the whole storage period; it was divided into three parts: softening Ia, weakening Ib, ripened II. There was a linear relation between bruise volume and the absorbed energy for fruits tested at all storage times. But over Ib and II the bruise volume was a relatively stable exponential function of the absorbed energy only. The lowest value of the energy absorbed by a fruit without any bruising decreased in Ia and was relatively stable in other parts. The effect of the Biofresh solution on the mechanical parameters was very limited, affecting only the hysteresis losses in Golden Delicious apples.     

RESPONSE OF BANANAS AND PLANTAINS TO IMPACT FORCES

Banana and plantains were obtained at green firm stage and stored at 20C and 90% relative humidity for up to 11 days. Some of the fruits were removed each day from storage and subjected to three impact energy levels (0.206, 0.514 and 0.828 J) using a specifically designed impacter. The impacted fruits were incubated at the same storage conditions for 24 h before assessing the bruise volume. Two models relating the bruise volume, the impact energy and the storage time were developed for both fruits. For bananas, the bruise volume had a linear relationship with the energy absorbed by the fruits, whereas the relationship was nonlinear for plantains. Plantains seemed to sustain less bruise volume than bananas during the initial storage period, but their bruise volume increased much faster in the subsequent storage days than bananas.     

Influence of Contact Surface Type on the Mechanical Damages of Apples Under Impact Loads

This paper presents an analysis of mechanical damage carried out on ‘Golden Delicious’ apple variety, which was subjected to impact loads during free drop against various rigid plates. For this purpose, an analysis of the contact pressure based on determined contours and surface pressure distributions at the contact point between the fruit dropped from various heights against fixed hard plates was performed. The impact test was conducted by means of Tekscan® system supported by computer verifying analysis. To obtain impact loads as well as their courses, the surface pressures and the bruise volumes were determined. Furthermore, use of ultra-thin pressure sensors allowed for determination of the characteristic shape of contact area and the impact of fruit onto rigid plate. The results showed that the impact of fruit against rigid surface (concrete, wood) generates high values of maximum surface pressure and the bruise volume, observed at dropping from 10 mm. A decrease in hardness of the test material (polyethylene foam) with decreasing maximum surface pressure approximately twice was noticed. The polyethylene foam is one of the best materials which protect fruit from mechanical damage, confirmed by the relation of bruise surface to contact surface, which did not exceed 35% during the impact at 150 mm. The results of proposed studies can contribute to developing of harvest, handling, and transport processes, aiming at reduction in losses among fruit growers and production costs, i.e., by improvement of transport method.     

The effect of fruit properties on the apricot bruises susceptibility

Some forces and impacts that occur during transporting and handling can reduce the apricot quality. Bruise damage is a major cause of fruit quality loss. Bruises occur under dynamic and static loading when stress induced in the fruit exceeds the failure stress of the fruit tissue. In this paper, two models were presented to evaluate the bruises susceptibility of apricots due to impact energy and peak contact force. Statistical prediction models of absorption energy were constructed to calculate “Ziaolmolki” apricot bruise susceptibility regarding fruit properties. The impacts were controlled by a pendulum. The regression models were made based on impact force and impact energy as the main independent variables and other parameters including fruit temperature, acoustic stiffness, colour parameter b* and radius of curvature. Pendulum was used to perform three levels of impact on apricot fruit. The main and interactions effects between variables were significant at 5 % probability level. It was demonstrated that increasing the temperature and curvature radius and lowering acoustical stiffness will reduce the bruise damage of the apricot fruit. Also, variance analysis indicated that three controlling factors, temperature, colour and impact force, significantly affected (P < 0.05) absorption energy.     

不同预冷降温速度对减轻桃果实采后机械伤的影响

桃果实营养丰富,易于消化吸收,深受消费者喜爱。但桃果实采后易遭受机械伤,导致腐烂损耗,严重影响商品价值。本实验以‘湖景蜜露’桃为材料,并对其进行不同降温速度的预冷处理(果心温度在3 h或16 h内从27℃降至9℃),以不进行预冷处理的材料为对照(Control check,CK),然后再对桃果实进行挤压机械伤处理(通过质构仪模拟挤压处理,探头直径100 mm,测试深度10 mm,挤压速度1.5 mm/s),以研究不同预冷降温速度对减轻桃果实采后贮藏物流过程中遭受机械伤的影响。结果表明,对桃果实进行预冷处理,尤其是3 h快速预冷处理,可以降低果实瘀伤指数、腐烂率和失重率,延缓果实硬度下降,并且还会加速苯丙氨酸裂解酶活性在贮藏后期的上升。其中经过3 h的快速预冷处理,果实瘀伤指数和腐烂率相较CK分别降低了11.7%和8.3%。预冷处理还可抑制桃果实因遭受机械伤而导致的呼吸速率、乙烯释放量、丙二醛含量和多酚氧化酶活性的上升,其中3 h快速预冷处理和16 h慢速预冷处理在贮藏21 d时的多酚氧化酶活性分别为CK的75.7%和72.1%。此外,预冷处理也会延迟总酚含量的上升,两个预冷处理组在贮藏...     

EFFECT OF GAMMA IRRADIATION ON THE POSTHARVEST PHYSIOLOGY OF FIVE BANANA VARIETIES GROWN IN INDIA

ABSTRACT— Gamma irradiation to 20–40 krad inhibits the ripening changes in preclimacteric bananas without affecting the fruit quality. Both fruit maturity at harvest and post-irradiation storage temperature markedly influence the response to irradiation. The optimum dose and the maximum tolerable dose varied among the five varieties screened. Ability of the banana fruit to withstand higher doses of gamma irradiation depends on the physiological status of the fruit at time of irradiation. Irrespective of varietal differences, irradiation of preclimacteric bananas to doses above 50 krad resulted in severe skin discoloration and fruit splitting. Irradiation under anoxia did not markedly reduce the radiation injury, suggesting that factors other than ozone formed during irradiation in air may contribute the radiation damage. Fruits on the climacteric could tolerate up to 200 krad but no effect on ripening rate was observed. Ethylene or 2,4-D could reverse irradiation-induced inhibition of ripening in bananas. Irradiation seems to decrease the sensitivity of banana fruit to the ripening action of exogenously added ethylene.     

EFFECT OF HARVESTING SEASON AND POSTHARVEST TREATMENTS ON STORAGE LIFE OF MEXICAN LIMES (Citrus aurantifolia Swingle)

Changes in susceptibility to chilling of citrus fruits vary with the low temperature applied, storage period, growing area, season, time of harvest and postharvest treatments. The objective of this study was to determine the effect of low temperatures on the quality of Mexican limes coated with wax applied through spraying or dipping, and treated with thiabendazole (TBZ) at 500 ppm and gibberellic acid (GA3) at 250 ppm. Weight loss, % of juice, degrees Brix, titratable acidity, color development and severity of chilling injury were examined weekly during storage. The results, obtained from fruit collected in two harvest periods, demonstrated that limes during the maximum production period of harvest in July, in contrast to those harvested in September, retained 90.6% of their fruit marketability. The conditions under which the best quality was obtained were the following: waxing by dipping + TBZ at 500 ppm + GA₃ at 250 ppm and 10C storage temperature with RH at 85–90%.     

DISCOLORATION OF SUN-DRIED AND PROCESSED ELBERTA PEACHES DURING STORAGE

Discoloration of sun-dried 'Elberta' (Prunus persica) peaches during a 48 week storage period as affected by moisture content (15 and 17%) and temperature (4, 7, 10 and 20C) was investigated. In addition, the effect of rehydration to moisture contents of 20, 24 and 27% and resulphuring on the color of the processed fruit during storage for 100 days at 0 and 25C was studied. Drying fruit to 15% instead of 17% moisture content gave darker-colored fruit, and it did not improve color retention during storage. Storage at 20C decreased L* values, indicating darkening of the fruit, but the quality, correlated with chroma, was still acceptable for fruit obtained with most of the treatment combinations. Substantial losses of SO₂ occurred at 20C. Rehydration and resulphuring increased chroma and hue values of the fruit. Storage of processed fruit at OC was effective in preventing discoloration, irrespective of treatment, while discoloration took place at 25C.     

低成熟度柑橘果实油胞病发病进程中的膜脂代谢

以接近成熟的低成熟度果实为实验材料,以果皮塌陷指数、变色指数以及与细胞膜相关的物质为测定指标,围绕果实膜脂降解途径展开,研究橙油处理致柑橘果实油胞病对果皮膜脂代谢的影响。结果表明,橙油处理可引起柑橘油胞病的发生,病症随贮藏时间的延长而加剧;橙油对果皮具有光毒性,细胞膜系统参与果实对油胞病的响应。橙油处理致油胞病使得磷脂酶D活性增加,磷脂酰胆碱、磷脂酰肌醇含量下降,磷脂酸含量上升,表明细胞膜水解加剧。发病早期脂氧合酶活性高于健康果实,使得果皮脂肪酸不饱和度下降,活性氧急剧产生,膜脂发生过氧化反应;过量的活性氧攻击细胞膜使得丙二醛含量和相对电导率持续上升;细胞膜结构和功能受损,从而促使油胞病发生并加剧油胞病症状。橙油致柑橘果实油胞病机制的明确为进一步研究柑橘油胞病及其防控措施提供了理论依据。     

THE EFFECT OF APPLE MATURITY AND FIRMNESS ON BRUISE VOLUME1

Red and Golden Delicious apples were tested to determine resistance to impact bruising with respect to day after bloom. Impact resistance measured by volume of bruised tissue was found to have a significant linear relation to day after bloom, firmness and bruise energy. Specific bruise volume (bruise volume per unit of energy input) did not change significantly over the growth period of the fruit when a constant drop height was maintained. This indicates that increases in bruising as the apple matures are due to increased weight of the fruit (bruise energy) rather than change in properties of the apple tissue.     

Pink discoloration in canned pears II.—Measurement of potential and developed colour in pear samples

Procedures are described for the comparative assessment of the leucocyanidin content of pears, which is the principal factor determining their susceptibility to discoloration on processing, and for measuring the shade and depth of discoloration in the processed material. Application of these procedures to pears of different varieties, storage treatment, and processing treatments lead to useful conclusions relevant to the discoloration problem, and establish relations between the three parameters under certain defined processing conditions. The results emphasise the difficulties associated with the assessment of the susceptibility of large consignments of pears to discoloration under normal canning operations.     

A new method to apply and quantify bruising sensitivity of button mushrooms

Mushrooms are prone to develop brown discolouration due to bruising caused by mechanical damage during harvest, which leads to reduced quality of the mushrooms. In order to study the mechanism behind discolouration and to breed for bruise-related browning resistant strains, a high throughput bruise application method and reliable quantification of browning sensitivity is essential. In this study a new bruising device was developed to bruise mushrooms in a fast and reproducible way. The bruising device can apply damage to the cap tissue of button mushrooms by a slip-shear sliding process. The severity of the bruise was quantified with a computer imaging system combined with a newly developed software programme. A protocol was developed to obtain the most reliable and reproducible method to compare browning sensitivity of different Agaricus bisporus strains. For this purpose, the extent of damage applied, time between harvest and bruising, developmental stage of the mushrooms and flushes were taken into account. The new method of bruising and image based quantification was subsequently applied to a collection of wild, commercial and hybrid A. bisporus strains and a distinction could be made between bruise-related browning sensitive mushrooms and tolerant mushrooms.     

MODIFICATION OF CONDITIONS AT THE WHOLESALE WAREHOUSE TO IMPROVE QUALITY OF FRESH-MARKET TOMATOES

Previous studies suggested that modification of storage temperatures at the wholesale warehouse could sufficiently retard ripening to permit harvest of fresh-market tomatoes at a later maturity, thus allowing for greater flavor development on the vine. Tomatoes (cvs ‘Celebrity’ and ‘Sunny’) were harvested either at the breaker or pink stages of maturity. Simulated wholesale storage was conducted by holding breaker fruit for 3 days at 12°C or 21°C and pink fruit for 3 days at 5°C or 37°C. Short-term low- and high-temperature storage of pink tomatoes delayed ripening sufficiently to maintain acceptable color and firmness during retail and consumer storage at 21°C for 7 days. Flavor characteristics of tomatoes harvested at the pink stage of maturity were not significantly superior to those of fruit harvested at the breaker stage. Thus, although ripening can be delayed in pink tomatoes during postharvest handling, delaying harvest from the breaker to the pink stage does not offer the flavor advantage to warrant a change in the handling system.     

苹果梨果皮中预存抗菌物质的提取、分离与鉴定

膨大期、采收期、采后100d的苹果梨果皮的乙醇(甲醇)-二氯甲烷粗提取液经TLC分离,以链格孢为指示菌进行生物活性分析均有不同比移值的抑菌带出现,采用气-质联用法(GC/MS)对其成分进一步分析表明,三个时期抑菌带成分存在差异。其中棕榈酸甲酯、油酸甲酯、亚油酸甲酯、鱼鲨烯(三十碳六烯)在膨大期含量最高,随着成熟和衰老的进行,含量逐渐降低,至采后100d,其含量分别为膨大期的1.8%、7.3%、19%和26.6%。推测它们是生长期间苹果梨果皮中存在的主要抗菌物质。邻苯二甲酸酯类是采收期和采后100d果皮中含量相对较高的抗菌物质,其中采后100d检出了6种邻苯二甲酸酯,相对含量高达60%。它们可能为采后果皮中主要的抗菌物质。     

MECHANICAL PROPERTIES AND TEXTURE OF STORED APPLES

Granny Smith, Delicious and Jonathan apples were placed in cool store immediately after harvest and were tested for ultimate tensile strength, fracture resistance and hysteresis of tensile specimens, and bruise resistance of whole apples under slow and impact compression over a period of 18 weeks. Sensory panel assessments of apple flesh texture were also made. Ultimate tensile strength and fracture resistance showed strong negative correlations with time for all varieties. Ultimate tensile strength decreased from 200–300 kPa at the beginning of the test period to 10 kPa at the end. Fracture resistance fell from 200–300 Jm⁻² to 10 Jm⁻² over the same time. The hysteresis ratio was unaffected by storage time but showed some effect of conditioning at 20° C for one week. Hysteresis ratios were between 0.1 and 0.2. Bruise resistance also remained fairly constant over the storage period for all varieties for both slow and impact compression. The explanation of this behaviour is the increase in the number of ruptured cells per unit volume of bruised tissue as storage time increases. Sensory panel assessment showed an inability to sense long term textural changes. There was, however, good correlation between panel assessment, ultimate tensile strength and fracture resistance for varietal effects and storage treatments. The tensile properties of apple tissue, namely, ultimate tensile strength and fracture resistance, provide a good measure of deterioration of apples during storage.     

Non‐freezing points below zero induce low‐temperature breakdown of kiwifruit at harvest

To induce low‐temperature breakdown (LTB) at harvest, a post‐storage disorder of kiwifruit, kiwifruit were exposed to ?2 °C (a temperature determined to be above the freezing point), for 0 (control), 6, 12, 18, 24, 30, 36 and 42 h, followed by 5 days at 20 °C. Kiwifruit were also stored at ?0.5 °C for 16 and 24 weeks plus 5 days at 20 °C. LTB incidence and severity were measured on the cut surfaces following slicing at the upper, middle and lower parts of each fruit subjected to ?2 °C, whereas in stored fruit LTB incidence was measured following slicing at the middle part. Electrolyte leakage (ELL) was also determined. Exposure of fruit to ?2 °C resulted in induction of LTB incidence and severity, which increased with the duration of exposure, particularly, on the upper fruit part. Maximum ELL during exposure at ?2 °C for 36 h or during storage at ?0.5 °C for 16 weeks was as high as 50% of that of the frozen fruit. Fruit exposed to ?2 °C or stored at ?0.5 °C had similar LTB symptoms but both differed from those observed in frozen fruit. LTB of fruit stored at ?0.5 °C for 24 weeks was 27% and corresponded to LTB induced at harvest by exposure at ?2 °C for 24 h. The results of this study confirm that LTB is inducible by low but not freezing temperatures at harvest and therefore it might be considered as the physiological basis towards the development of an LTB incidence index for harvested kiwifruit. Copyright © 2006 Society of Chemical Industry     

EFFECT OF STORAGE TIME ON THE MALTING QUALITY OF SOME BARLEY VARIETIES

Changes in the malting quality of some barley varieties were monitored at monthly intervals from harvest All the varieties were found to improve after storage for up to one year. Varieties with poorer malting grades improved at a faster rate than good varieties, although ranking consistent with malting grade was maintained.