A survey of ellagitannin content in raspberry and blackberry cultivars grown in Trentino (Italy)

This study describes the first application of a new procedure for acid hydrolysis of Rubus ellagitannins in methanol, which allows quantification of all the major reaction products (ellagic acid, methyl-sanguisorboate, methyl gallate and an unknown ellagic acid derivative) and estimation of the mean degree of polymerization (mDP) of Rubus ellagitannins. The ellagitannins of 21 raspberry and 15 blackberry cultivars produced in Trentino, Italy during 2005 were extracted and characterised. The total content of ellagitannins was shown to vary by a factor of 2 among raspberry cultivars and by a factor of 4 among blackberry cultivars.     

Freezing, thawing and cooking effects on quality profile assessment of green beans (cv. Win)

Results are presented of the effect of freezing followed by thawing (air and water immersion, both at environmental temperature) and cooking (traditional boiling in a covered pot) on quality profile (in terms of objective texture, colour, chlorophylls and pheophytins and sensory attributes) and structure of green beans (cv. Win). Freezing was carried out at three different rates by forced convection with liquid nitrogen vapour. Kramer shear cell (KSC) and Warner–Bratzler (WB) tests were used for objective assessment of the texture. The highest parameter values occurred in beans frozen at the highest rate and air-thawed at the slowest rate. Also, minimum alteration of the rheological behaviour of cooked beans was achieved by freezing at the highest rate. The best parameter for assessing the texture of frozen green beans after thawing and cooking was the Warner–Bratzler slope (S _WB). Coefficients of softening estimated for S _WB in the thawed beans showed that the texture of the beans frozen at −24 °C was almost four and almost five times softer than that of the beans frozen at −70 °C, for air and water thawing respectively. Frozen and thawed green beans were darker than fresh control, whereas freezing prior to cooking produced lighter-coloured beans than direct cooking. The freezing rate affected colour parameters differently depending on the process that followed. When beans were thawed, increasing the freezing rate produced lighter-coloured beans, whereas when beans were cooked, increasing the rate produced darker-coloured beans. No difference was found in sensory assessments between cooked samples frozen at −24 °C, −35 °C and −70 °C, which probably reflects the panellists' mixed preferences for quickly and slowly frozen samples. Scanning electron microscopy (SEM) revealed different degrees of mechanical damage to tissue structure, which accounted for the rheological behaviour of the beans.     

Effect of canning process on texture of Faba beans (Vicia Faba)

The effects of different treatments such as traditional cooking, sterilizing at different time–temperature combinations and the addition of different brines on instrumental texture were evaluated. Previously, a comparison of different texture-measuring devices and optimisation of instrumental texture analysis were carried out. The results showed that all the texture-measuring devices used differentiated perfectly among the different products tested. Regarding heat treatments assayed, different sterilization treatments affected skin texture but had no significant effect when whole grain was considered. Finally, the addition of chelation agents to the brine did not affect the textural parameters but the commercial quality related to the production of Faba beans under a “Geographical Indication” had an important effect on the firmness of both the pericarp and whole seed and on pectin content.     

超高压处理对黑莓酒香气成分的影响

运用超高压技术处理黑莓酒以期改善其香气品质,并采用固相微萃取与气相色谱-质谱联用对不同超高压条件处理的黑莓酒挥发性香气成分进行检测,探究超高压处理对黑莓酒香气成分的影响及作用机理.结果表明:经超高压处理的黑莓酒香气种类与未处理样品相同,但含量发生较大变化,200MPa处理20min的黑莓酒醇类、酯类和醛类无显著变化(p＞0.05),酸类减少了7.44％;600MPa处理20min的黑莓酒醇类、酯类分别增加了4.63％、13.38％,醛类、酸类无显著变化(p＞0.05);400MPa处理20min的黑莓酒醇类、酯类和醛类分别增加了4.89％、43.04％和1.12％,酸类减少了11.28％,整体香气趋向柔和、协调、饱满,达到改善黑莓酒香气品质的目的.     

Effects of refrigeration,freezing and replacement of milk fat by inulin and whey protein concentrate on texture profile and sensory acceptance of synbiotic guava mousses

The effects of refrigeration, freezing and substitution of milk fat by inulin and whey protein concentrate (WPC) on the texture and sensory features of synbiotic guava mousses supplemented with the probiotic, Lactobacillus acidophilus La-5, and the prebiotic fibre oligofructose, were studied. The frozen storage (−18 ± 1 °C), followed by thawing at 4 °C before the analyses, and the complete replacement of the milk fat by inulin plus WPC, led to significant differences in the instrumental texture parameters of mousses (P < 0.05). Nonetheless, these changes did not affect the sensory acceptability of the products studied. The frozen storage may be employed to extend the shelf-life of synbiotic guava mousses. Additionally, to obtain a texture profile similar to the traditional product, the simultaneous addition of inulin and WPC is recommended only for the partial replacement of milk fat in refrigerated and frozen mousses, and the total proportion of both ingredients together should not exceed 2.6%.     

The effect of the pre-treatments and the long and short-term frozen storage on the quality of raspberry (cv. Heritage)

Results are presented of the effect of pre-treatments before freezing followed by long and short-term frozen storage (12 months at –18 °C and 24 days suffering temperature fluctuations between –18 °C and –12 °C) on quality parameters of raspberry. Pre-treatments were carried out with calcium, low methoxyl pectin, a combined solution, and results compared with untreated control fruits. Kramer shear, back extrusion, compression, and multiple penetration tests were used to measure rheological behavior. One-hundred mM CaCl₂ reduced the long and short-term frozen storage induced loss of firmness. For long-term storage at –18 °C, a softening of the tissue became evident between 3 and 12 months and at each date test the stored fruits were firmer than those without storage. For short-term storage with fluctuations, the loss of firmness was evident between 0 and 24 days, and at all the testing dates the stored fruits were softer than those without storage. Results evidenced a higher cell damage in the short-term frozen storage. Coefficients of softening per day suffering fluctuation were determined, the highest values being given by Kramer shear energy and back extrusion maximum force (>1%). Short-term frozen storage affected physical and physico-chemical characteristics, increasing the saturation (r) and the anthocyanins and decreasing the ascorbic acid of the raspberries. In both storage conditions, pre-treatments reduced the drip loss, which correlated best with the Kramer shear energy. Panelists detected mainly time effect on the sensory firmness. For long-term, sensory firmness and juiciness gave the highest correlations with back extrusion maximum force, while for the short-term, sensory firmness and drip loss gave the highest correlations with the Kramer shear energy. SEM revealed different degrees of mechanical damage to structure, which accounted for rheological behavior of the fruits.     

食品质感性能的主客观评价技术分析

食品的质感性能是固体或半固体食品的四大质量要素之一,强烈地影响着消费者对产品的接受程度和消费意愿。对食品质感性能的评价与检测,是改进产品设计和生产工艺、控制产品质量、满足消费者需要、提高企业效益不可或缺的技术手段。食品质感性能评价技术传入我国已有多年,各种先进的检测方法和试验设备已被广大食品研发人员所接受,但在使用过程中,主客观分析结果所表现出来的巨大偏离,一直困扰着许多研究人员,严重制约着食品质感性能分析技术的推广和发展。本文试图从定义及发展过程出发,阐述食品质感性能主客观分析技术的基本原理及使用过程可能存在的误区,并根据作者的学术背景,从力学的角度提出了食品质感性能及其评价方法今后发展的一些思考。     

Evaluating instrumental colour and texture of thermally treated New Zealand King Salmon (Oncorhynchus tshawytscha) and their relation to sensory properties

Farmed New Zealand King Salmon (Oncorhynchus tshawytscha) was prepared according to common consumer techniques, namely poached, steamed, microwaved, pan fried (no oil), oven baked (no oil) and deep fried (in sunflower oil). Colour and texture were measured instrumentally and a sensory evaluation comprising of a generic QDA was conducted for the intensity and overall liking of the properties of colour, texture, flavour and aroma.During the thermal treatment (cooking), the outer colour of the King Salmon fillets became lighter, more red and yellow. Thermal treatment increased the texture firmness, chewiness and springiness of King Salmon as measured by texture analyser. Overall, the sensory panel preferred the oven baked King Salmon but least liked the poached and microwaved King Salmon. The instrumental texture measurements of the cooked King Salmon were closely linked with the texture ratings from the sensory panel. These experiments provide useful data for determining the optimal preparation techniques that in turn can facilitate the farming of NZ King Salmon to directly benefit the consumer.     

Reducing salt and fat content: Impact of composition,texture and cognitive interactions on the perception of flavoured model cheeses

To better understand which composition levers are available to reduce salt content in food without altering flavour perception, this paper aimed at quantifying the impact of texture and composition (salt, fat and dry matter) of a model cheese: (i) on salt and flavour perception, and; (ii) on profile texture and flavour release.     

Impact of industrial processing and storage on major polyphenols and the antioxidant capacity of tropical highland blackberry (Rubus adenotrichus)

Critical steps of a typical industrial line for processing a blackberry-based beverage in glass bottles have been studied, together with the effects of storage of final product at four different temperatures. For the steps, contents of total phenolics, anthocyanins, ellagitannins, and minor phenolic compounds were assessed by HPLC-DAD and antioxidant capacity by H-ORAC and DPPH. Thermal processes, especially blanching, drastically reduced anthocyanins, whereas hot-filling degraded ellagitannins. The final product showed reduced values for the anthocyanins cyanidin-3-glucoside (by 52%) and cyanidin-3-malonyl glucoside (64%), and ellagitannins lambertianin C (80%), and sanguiin H-6 (50%). Antioxidant capacity (H-ORAC) dropped by almost 47%. The anthocyanins and ellagitannins continued degrading during storage, especially if temperatures were high. Reduction kinetic parameters during storage were estimated for anthocyanins and, for the first time, for both lambertianin C and sanguiin H-6.     

Effect of batter freezing conditions and resting time on cake quality

The aim of the present study was to investigate the effects of batter freezing and conditions and resting time before baking on quality of two kinds of cakes (layer and sponge cakes), including freezing temperature (−18 °C, −26 °C), storage time at sub-zero temperatures (30 and 100 days), and resting time (60 and 120 min). Characteristics of the batter (pH, density, viscosity, and microstructure) and cakes (density, texture, and colour) were analysed. Freezing process increases batter density and viscosity, and consequently decreases cake volume and height, but increases hardness. Cakes from frozen batters have a darker and more yellow crumb and lighter-coloured crust than cakes from non-frozen batters. Freezing process has a greater effect on batter and cake quality characteristics than storage/freezing conditions or resting time. In layer cakes, freezing mainly affected volume and colour, whilst in sponge cakes, there was a more marked effect on texture. Differences between the two kinds of cake could be related to a distinct internal structure. Resting time mainly affected batter characteristics, although there were no apparent differences in the quality of the cakes obtained.     

Impact of pretreatment and freezing conditions on the microstructure of frozen carrots: Quantification and relation to texture loss

The textural quality of carrots subjected to pretreatments affecting the pectin structure in combination with different freezing conditions was studied. Carrot samples frozen under different conditions were extensively studied by light microscopy quantifying the freezing damage based on the analysis of different parameters (number, area, perimeter, and shape factor of tissue particles) associated with carrot tissue damage. The reduced texture loss of rapidly or cryogenically frozen carrots, compared to slowly frozen samples, was associated with the reduction in cell wall damage in the carrot tissue. In case no pretreatment was used, carrot texture was only slightly improved by using high-pressure shift freezing instead of slow freezing. Detailed analysis of the different steps involved showed that severe tissue damage occurred during the completion of the high-pressure freezing process at atmospheric pressure. However, tissue damage, and thus texture loss, of high-pressure frozen carrots could be minimized by applying pretreatments consisting of a thermal treatment at 60 °C and a high-pressure treatment at 300 MPa and 60 °C.     

Effect of Hydrocolloid Pre-Treatment on Instrumental and Sensory Texture Attributes of Frozen Carrot (Daucus carota)

The effect of different hydrocolloids (pectin, carboxy methylcellulose, xanthan gum, and sodium alginate) pre-treatment used at different concentrations (0.2–0.4%) on instrumental texture parameters as well as on the sensory attributes of frozen-thawed pre-cut carrots was evaluated. Instrumental texture profile analysis of frozen-thawed carrot showed a significant (P < 0.05) increase in cohesiveness with an increase in the concentration of all the hydrocolloids. Nevertheless, the increase in springiness was not significant (P > 0.05) over the untreated control samples, whereas chewiness did not show consistent results with an increase of any of the hydrocolloids. As the concentration of hydrocolloids increased, the firmness values obtained by cutting the frozen-thawed carrot samples with a Warner Bratzler Blade were also found to increase. Higher texture retention after freezing and thawing was observed in xanthan gum (0.4%) pre-treated samples than other hydrocolloids used as well as than the control samples. It increased the firmness up to 196.2% than the control samples. However, 0.3% xanthan pre-treatment gave the best sensory results. Sensory acceptability increased on increasing the pectin and carboxy methylcellulose concentrations, while lower concentration levels of alginate pre-treatment showed higher sensory preference than the higher concentration levels. Based on the results, untreated frozen samples suffered from a detrimental texture and sensory deterioration during 15 months of frozen storage. The carrot tissue integrity was well retained during frozen storage in the hydrocolloid pre-treated samples.     

Freezing protocol effect on quality properties of fruit tissue according to the fruit, the variety and the stage of maturity

Among the changes induced by freezing of fruits, it is still difficult to determine the major properties which are the most representative of quality variation. A range of characteristics (texture, color, soluble solids, water activity, water content, pH, titrable acidity) were determined before and after three different freezing protocols (at −20 °C in a cold chamber, at −80 °C in gas nitrogen convection chamber and after immersion in liquid nitrogen at −196 °C) for two fruit types (apple-Malus domestica Borkh- and mango - Mangifera indica L. cv. ‘KENT’-), two varieties of apples (Golden Delicious and Granny Smith) and two maturities of one variety (ripe and unripe Granny Smith). Freezing induced significant changes mostly in texture, color and soluble solids. Property variations due to freezing depended mainly on the type of fruit, to a lesser extent on the variety of apples studied and slightly on the maturity of Granny Smith apples. Among the freezing conditions tested, gas nitrogen convection at −80 °C appeared to be the best choice for limiting fruit quality degradation.     

Effect of temperature fluctuations during frozen storage on the quality of potato tissue (cv. Monalisa)

 Results are presented on the effect of different ranges of temperature fluctuation (–24 to –18°C, –18 to –12°C, –12 to –6°C, –24 to –12°C and –18 to –6°C) on the compression, shear and tension parameters of packed and unpacked frozen potato tissue. The initial temperature, duration and number (2, 4, 8, 16, 24 and 32) of fluctuations were varied. The highest parameter values occurred in samples subjected to fluctuations between –24°C and –18°C, and the lowest values in the range –18 to –6°C. The mechanical strength of the frozen tissue decreased with an increase in the number of fluctuations and in most cases was lower in the packed samples. Moisture loss was greatest in the –18 to –6°C range for pre-packed samples. Changes in the maximum compression force, as a measure mechanical damage, showed the greatest level of significance. Received: 17 June 1997     

Effect of temperature fluctuations during frozen storage on the quality of potato tissue (cv. Monalisa)

 Results are presented on the effect of different ranges of temperature fluctuation (–24 to –18°C, –18 to –12°C, –12 to –6°C, –24 to –12°C and –18 to –6°C) on the compression, shear and tension parameters of packed and unpacked frozen potato tissue. The initial temperature, duration and number (2, 4, 8, 16, 24 and 32) of fluctuations were varied. The highest parameter values occurred in samples subjected to fluctuations between –24°C and –18°C, and the lowest values in the range –18 to –6°C. The mechanical strength of the frozen tissue decreased with an increase in the number of fluctuations and in most cases was lower in the packed samples. Moisture loss was greatest in the –18 to –6°C range for pre-packed samples. Changes in the maximum compression force, as a measure mechanical damage, showed the greatest level of significance. Received: 17 June 1997     

The Effect of Cooking Water Composition on Textural and Cooking Properties of Spaghetti

The effect of cooking water on both textural and cooking properties of spaghetti was investigated for spaghetti samples, which differ in protein content. The samples were analysed after cooking in deionised, laboratory tap water, deionised water with 2.5% salt and deionised water with 5.0% salt. Brands A, B, and C were usual durum wheat spaghetti and brand D was spaghetti enriched with bran. Regardless of the cooking water used, brand D had higher hardness and lower adhesiveness than other spaghetti samples and required longer cooking time to achieve optimum cooking. It was found that samples cooked deionised water had lower hardness and adhesiveness values as compared to samples cooked in salty water. It can be concluded that a certain amount of salt in the cooking water improves textural characteristics of cooked pasta.     

Effect of modified starch concentration and freezing and thawing rates on properties of mashed potatoes (cv. Kennebec)

Effects of modified cornstarch concentration, freezing rate and thawing mode on quality properties of mashed potatoes were examined. The product was tested by oscillatory rheometry, instrumental texture profile analysis (ITPA) and cone penetration, colour, dry matter (DM) and sensory analyses. Oscillatory parameters showed that increasing starch concentration resulted in a softer product in which gel strength decreased in direct proportion to concentration in quick‐frozen and microwave‐thawed product. Quick freezing made for firmer mashed potatoes, whereas oscillatory, ITPA and penetration parameters were lower in the samples thawed at 4 °C. Starch concentration and instrumental consistency and firmness were directly proportional to one another. Adding starch at the highest concentration, quick freezing and slow thawing produced a lighter‐coloured mashed potato, although the loss of colour in the processed product was not detected by panellists in the microwave‐thawed samples. DM was higher in the quick‐frozen samples and lower in air‐thawed samples. The factors studied affected different sensory texture parameters but had hardly any effect on attributes perceived during final and residual phases of mastication. Only starch concentration had a significant effect on sensory acceptability, but interactions between factors showed that starch addition followed by quick freezing was judged undesirable by the panellists due to excessive softening. Oscillatory parameters correlated well with sensory texture attributes and proved quite precise. They would therefore appear to be the best test to monitor properties of frozen mashed potatoes. Copyright © 2007 Society of Chemical Industry