Kiwifruit Puree Research Articles

Spray-Drying of Green or Gold Kiwifruit Juice–Milk Mixtures; Novel Formulations and Processes to Retain Natural Fruit Colour and Antioxidants

This study describes novel formulations and approaches to produce reconstitutable (in water) spray dried kiwifruit milk powders that possess the intrinsic fruit colour and antioxidants of kiwifruits. Novel feed formulations, containing the aqueous fraction of green or gold kiwifruit puree, skim milk, fortifying zinc (in the form of zinc citrate) and a minimal amount of maltodextrin (3 % w/w), were spray dried at a relatively low inlet temperature (150 °C) to produce kiwifruit juice–milk powders with good dissolution efficiency (complete dissolution in 21–28 s), low water activity (0.22–0.28) and high retention of vitamin C, phenolics and carotenoid antioxidants. Both the green and gold kiwifruit juice–milk powders were pseudoplastic-like materials. Their reconstituted aqueous solutions had viscosity of 2–23 mPa · s and exhibited a shear rate dependence. Adding kiwifruit pulp residue to the feed solution at a mass ratio of 25:75 significantly enhanced the dissolution efficiency and the natural kiwifruit colour of the product powders without affecting the total phenolic and vitamin C contents. Preheating the feed solution to 50 °C for 1 min had a positive impact on the physicochemical attributes and bioactive profile of kiwifruit juice–milk powders, including a greater retention of initial kiwifruit juice colour, lower water activity, better dissolution efficiency and a higher total phenolic content. The powders obtained in this study contain multiple health-promoting nutrients and bioactives including kiwifruit antioxidants and milk proteins, and can be used in beverages or as functional ingredients for nutraceutical applications.

Quality and Acceptability of Microwave and Conventionally Pasteurised Kiwifruit Puree

The development and optimisation of food preservation processes seem to be necessary in order to address consumer expectations related to secure, fresh-like foods. To this end, the sensory, nutritional and functional properties must be maximally retained. In order to contribute to the acquisition of knowledge about the adequacy of microwave processing as a means of preserving fruit-based products, the present study compares the impact of microwave heating with conventional thermal processing. The consumer acceptance of fresh and pasteurised kiwifruit puree was studied as was the content of water, soluble solids and bioactive compounds and the pH, consistency, viscosity, colour coordinates and antioxidant capacity, as well as the effect of the thermal treatment on enzyme and microbial inactivation. As bioactive compounds, the content of vitamins C, A and E and the total flavonoid, phenol and tannin content have been considered. As the obtained results show, not only was microwaved puree preferred by consumers, but it also exhibited a superior maintenance of the nutritive and functional properties of the fruit, smaller colour changes and a content of inactivated enzymes and microorganisms equal to or greater than the conventionally heated sample.

Listeria monocytogenes inactivation kinetics under microwave and conventional thermal processing in a kiwifruit puree

The inactivation of Listeria monocytogenes in a kiwifruit puree by conventional and microwave heating was studied. Survival curves at three microwave power levels (600–1000 W) and three temperatures (50–60 °C) were obtained. Data were properly fitted by a first-order kinetic model. Processing times under both technologies were corrected to isothermal treatment for the kinetic study. Microwave heating was shown to effectively inactivate L. monocytogenes. In the range of microwave and conventional processing conditions assayed, the 5-log10 reductions of L. monocytogenes recommended by the FDA for pasteurized products were achieved. The level of microwave power applied had a considerable influence on the L. monocytogenes inactivation rate. The higher the power level, the faster the inactivation. The inactivation of L. monocytogenes under microwave heating at 900 W (D60 °C = 17.35 s) and 1000 W (D60 °C = 17.04 s) happened faster than in a conventional thermal process (D60 °C = 37.45 s). Consequently, microwave heating showed greater effectiveness for L. monocytogenes inactivation than conventional heating. Consumers' desires are oriented towards new foods that are convenient, easy to preserve and ready-to-eat products, being consumption of fresh fruit replaced with processed fruit products. Food industry is currently focused on the development of novel and minimally processed products with improved quality. Thus, a variety of new processing technologies are being explored as alternative to traditional thermal processing. In this work, the thermal and microwave inactivation kinetics of Listeria monocytogenes in a ready-to-eat kiwifruit puree were investigated so as to assess the suitability of microwave processing as an alternative to thermal processing. The results of this study point out that more than conventional heating, microwave technology can be an appropriate means of fruit product pasteurization with the possibility of offering the required safety by using a lower process time, when microwave power of a certain level is applied.

Overall quality properties in pressurized kiwi purée: Microbial, physicochemical, nutritive and sensory tests during refrigerated storage

Abstract A suitable option for exploiting kiwifruit is to develop a processed product. High pressure treatment (HPT) was applied to kiwi puree and chill-stored for two months. Measurements during storage were: °Brix, pH, color, vitamin C, citric and malic acids, glucose, fructose, sucrose, microbial levels and sensory tests. HPT reduced the initial microbial load by 4 log; pH and °Brix were constant throughout storage and unaffected by pressurization. Just after the treatment, sugars and organic acids in the pressurized samples decreased by around 40 and 50%, and the color parameter a* increased by 50%. However, the levels remained almost constant and were similar in the unprocessed samples after five storage days. Similarly, the sensory assays showed significant differences between the treated and untreated kiwi purees during the initial storage days, but after one storage week the differences decreased. HPT appears to be a good alternative for processing kiwi puree. Industrial relevance Pasteurization of fruit purees with a high pressure treatment (HPT) has received considerable attention during recent years and will become a proper industrial application in the future for exploiting kiwi surplus production. The overall quality data obtained in this work demonstrate that high pressure processing followed by chilled storage can extend the shelf-life of kiwi puree while maintaining its overall quality. Sensory measurements made by panelists and consumers are an important tool for deciding on the effectiveness of pressurization for certain processed fruit product.

Impact of temperature on lethality of kiwifruit puree pasteurization by thermal and microwave processing

The use of pasteurization units (PU) as a measure of the lethal effect of processes was proposed with the aim of comparing conventional and novel thermal technologies. Kiwifruit puree was subjected to microwave (1000 and 900 W) and conventional (97 °C) heating. Processing conditions of the treatments were chosen to simulate a pasteurization treatment. The temperature profiles of the samples during processing were recorded at different positions. The coldest and hottest spots of the product were identified and the associated PU numbers were calculated. A significantly (p < 0.05) higher thermal load was necessary in order to stabilize the kiwifruit puree under conventional (19.27 min) than microwave heating mode (0.003–8 min) at any of the conditions studied. The higher effectiveness of microwave heating could be attributed to non-thermal effects associated with this technology.

Comparison of microwaves and conventional thermal treatment on enzymes activity and antioxidant capacity of kiwifruit puree

Enzymes are naturally present in food and can cause product deterioration. For this reason, most food-processing steps try to reduce the enzymatic activity. The aim of this work was to compare, in terms of both the inactivation of kiwifruit puree peroxidase, polyphenoloxidase and pectinmethylesterase and also the maintenance of the antioxidant capacity of the product, the effect of a microwave treatment with a conventional thermal treatment designed to cause the same level of peroxidase inactivation (90%). The microwave power and process time that best permitted the maximisation of both the enzyme inactivation and the antioxidant capacity of the product, were selected by means of the Response Surface Methodology. The results obtained point to microwave heating as an appropriate technology with which to produce a stable kiwifruit puree, since these treatments were more effective at enzyme inactivation and antioxidant capacity retention than the conventional thermal treatment. Food industry is currently focused on the development of novel and minimally processed products with improved quality. Traditional thermal processing has been assumed to require the use of high temperatures and long times to stabilise food products, which lead to dramatic losses of products' quality. Thus, a variety of different processing technologies are being explored as alternative to traditional thermal processing. The results of this study point out that more than conventional heating, microwave technology can be an appropriate means of achieving the required level of enzyme inactivation at which to obtain a stable kiwifruit puree with an improved antioxidant capacity.

Kinetics of chlorophyll degradation and color loss in heated kiwifruit puree

Kinetics of chlorophyll degradation and color loss in heated kiwifruit puree

Effects of Microwave Heating on Sensory Characteristics of Kiwifruit Puree

The effect of microwave processing on the characteristics of kiwifruit puree was evaluated by applying various gentle treatments. Different combinations of microwave power/processing time were applied, with power among 200–1,000 W and time among 60–340 s, and various sensory and instrumental measurements were performed with the aim of establishing correlations and determining which instrumental parameters were the most appropriate to control the quality of kiwi puree. The water and soluble solids of the product, 83 and 14/100 g sample, respectively, did not change due to treatments. For sensory assessment, an expert panel was previously trained to describe the product. Fourteen descriptors were defined, but only the descriptors ‘typical kiwifruit colour’, ‘tone’, ‘lightness’, ‘visual consistency’ and ‘typical taste’ were significant to distinguish between kiwifruit puree samples. The instrumental analysis of samples consisted in measuring consistency, viscosity, colour and physicochemical characteristics of the treated and fresh puree. Applying intense treatments (600 W–340 s, 900 W–300 s and 1,000 W–200 s) through high power or long treatment periods or a combination of these factors, mainly affects the consistency (flow distance decreased from 5.9 to 3.4 mm/g sample), viscosity (increased from 1.6 to 2.5 Pa/s), colour (maximun ΔE was 6 U) and taste of the product. As a result, samples were thicker and with an atypical flavour and kiwifruit colour due to increased clarity (L* increased from 38 to 43) and slight changes in the yellow–green hue (h* decreased from 95 to 94). For the instrumental determinations of colour and visual perception of consistency, the most suitable parameters for quality control are the colour coordinates L*, a*, h*, whiteness index and flow distance measured with a Bostwick consistometer.

Gold kiwifruit leather product development using Quality function deployment approach

In the product design and development process, Quality function deployment (QFD) provides a comprehensive, systematic approach to ensure new products meet or exceed customer expectations. QFD can be a powerful tool because it can reduce time to market, improved quality and increased customer satisfaction. The techniques that were employed in the study included: consumer surveys, quantitative descriptive analysis (QDA), and Quality function deployment (QFD). A consumer survey of 400 Thai respondents showed a high proportion of consumers (25%) ate fruit leather once or more often/week. Thai consumers were also asked to evaluate seven representative fruit leather products using a 9-point hedonic scale for various sensory attributes as well as overall liking and their responses together with data that was obtained from a QDA panel was used in the QFD to define the importance of the various sensory characteristics for the design of a new fruit leather. Based on customer requirements, the most important of product technical specifications found from QFD were the sweetness and hardness. The important process parameters related to such technical specifications were glucose syrup for the sweetness and pectin for control of the product’s textural characteristics. A 32 factorial design was used to optimize the addition levels of glucose syrup and pectin in gold kiwifruit leather. A recipe with 15g glucose syrup and 2g pectin per 100g gold kiwifruit puree had the highest hedonic score.

Kiwifruit-based polyphenols and related antioxidants for functional foods: kiwifruit extract-enhanced gluten-free bread

The present study investigates the production of gluten-free bread enhanced with polyphenols and related antioxidants derived from a natural aqueous extract from green-fleshed kiwifruit (Actinidia deliciosa). Puree and four aqueous extracts, produced from ripe green kiwifruit in the absence of artificial preservatives, were subjected to storage stability trials at 4°C, 20°C and 38°C, and were chemically characterized (phenolic, vitamin C and pectic polysaccharide contents). The aqueous extract with good stability and high phenolic and vitamin C contents was used for gluten-free bread-making. The resultant kiwifruit extract-enhanced bread was acceptable to a taste panel, possessing softer and smoother texture than plain gluten-free bread. Thus, the aqueous extract of kiwifruit puree containing health-beneficial constituents can be considered a functional ingredient for gluten-free bread formulation.

Effect of extraction techniques and conditions on the physicochemical properties of the water soluble polysaccharides from gold kiwifruit (Actinidia chinensis)

SummaryThe extraction of nonstarch polysaccharides from fruits and vegetables has received much attention recently in terms of their utilisation in functional food systems. In New Zealand kiwifruit production is one of the major fruit growing exploits. This paper explores the potential extraction techniques which may be employed to extract water soluble polysaccharides from kiwifruit material, in an attempt to utilise this commodity as an added value food ingredient. Crude water soluble polysaccharides of fresh gold kiwifruit were extracted under different extraction techniques (acid, hot water and enzyme) and conditions (time, temperature and concentration). The recovery of water soluble polysaccharide fraction (WSP), chemical composition, and their rheological behaviour were examined. The extraction technique had a significant effect on the WSP yield, galacturonic acid content, as well as the viscosity. Enzymatic extraction method yielded higher WSP and galacturonic acid than water and acid extraction, but this fraction exhibited lower viscosity. Acid extracted WSP yield decreased with increasing temperature and time. In contrast, water extracted WSP yield increased with increasing temperature and time. The selected extraction parameters for acid extraction were temperature 50 °C, extraction time 60 min, and 1:6 kiwifruit puree to acid solution ratio. The water extraction optimum parameters were 25 °C, 30 min and 1:4 puree to water ratio and 25 °C, 30 min with medium concentration for enzymatic extraction. The WSP viscosity and galacturonic acid content was maximum under these extraction conditions.

Feeding ZESPRI™ GOLD Kiwifruit puree to mice enhances serum immunoglobulins specific for ovalbumin and stimulates ovalbumin-specific mesenteric lymph node cell proliferation in response to orally administered ovalbumin

The health benefits of fruits have been recognized for some time, but only recently have their effects on the immune system been investigated. Kiwifruit contains vitamins, minerals, and phytochemicals that are known to be important for normal functioning of the immune system. In this work, the influence of feeding 2 ZESPRI GOLD Kiwifruit processed products (Tauranga, New Zealand) on immune function in mice was investigated. Using a model to demonstrate adaptive immune responses in the gut, mice were fed either ZESPRI GOLD Kiwifruit puree or ZESPRI GOLD Kiwifruit 40 degrees Brix Juice concentrate for 20 days, during which time they were immunized via the oral route with ovalbumin and subsequently given a suboptimal dose of the mucosal adjuvant cholera toxin. ZESPRI GOLD Kiwifruit puree enhanced the response to ovalbumin by significantly increasing the levels of total immunoglobulins and immunoglobulin G specific for ovalbumin and enhanced the antigen-specific proliferation of cells from the draining mesenteric lymph nodes compared with mice fed a 20% sugar control. These results indicate that ZESPRI GOLD Kiwifruit can modulate an antigen-specific immune response and suggest that ZESPRI GOLD Kiwifruit may represent a new type of functional food ingredient.

Specific Detection of Potentially Allergenic Kiwifruit in Foods Using Polymerase Chain Reaction

Kiwifruit (Actinidia deliciosa and Actinidia chinensis) is allergenic to sensitive patients, and, under Japanese regulations, it is one of the food items that are recommended to be declared on food labeling as much as possible. To develop PCR-based methods for the detection of trace amounts of kiwifruit in foods, two primer pairs targeting the ITS-1 region of the Actinidia spp. were designed using PCR simulation software. On the basis of the known distribution of a major kiwifruit allergen (actinidin) within the Actinidia spp., as well as of reports on clinical and immunological cross-reactivities, one of the primer pairs was designed to detect all Actinidia spp. and the other to detect commercially grown Actinidia spp. (i.e., kiwifruit, Actinidia arguta, and their interspecific hybrids) except for Actinidia polygama. The specificity of the developed methods using the designed primer pairs was verified by performing PCR experiments on 8 Actinidia spp. and 26 other plants including fruits. The methods were considered to be specific enough to yield target-size products only from the target Actinidia spp. and to detect no target-size products from nontarget species. The methods were sensitive enough to detect 5-50 fg of Actinidia spp. DNA spiked in 50 ng of salmon testis DNA used as a carrier (1-10 ppm of kiwifruit DNA) and 1700 ppm (w/w) of fresh kiwifruit puree spiked in a commercial plain yogurt (corresponding to ca. 10 ppm of kiwifruit protein). These methods would be expected to be useful in the detection of hidden kiwifruit and its related species in processed foods.

Comparative study on pressure and temperature stability of 5-methyltetrahydrofolic acid in model systems and in food products.

A comparative study on the pressure and temperature stability of 5-methyltetrahydrofolic acid (5-CH(3)-H(4)folate) was performed in model/buffer systems and food products (i.e., orange juice, kiwi puree, carrot juice, and asparagus). Effects of pH and ascorbic acid (0.5 mg/g) on 5-CH(3)-H(4)folate stability in buffer systems were studied on a kinetic basis at different temperatures (from 65 to 160 degrees C) and different pressure/temperature combinations (from 100 to 700 MPa/from 20 to 65 degrees C). These studies showed that (i) the degradation of 5-CH(3)-H(4)folate in all model systems could be described by first-order reaction kinetics, (ii) the thermostability of 5-CH(3)-H(4)folate was enhanced by increasing pH up to 7, (iii) 5-CH(3)-H(4)folate was relatively pressure stable at temperatures lower than 40 degrees C, and (iv) ascorbic acid enhanced both the thermo- and barostabilities of 5-CH(3)-H(4)folate. In food products, temperature and pressure stabilities of 5-CH(3)-H(4)folate were studied at different temperatures (70-120 degrees C) and different pressure/temperature combinations (from 50 to 200 MPa/25 degrees C and 500 MPa/60 degrees C). 5-CH(3)-H(4)folate in orange juice and kiwi puree was relatively temperature (up to 120 degrees C) and pressure (up to 500 MPa/60 degrees C) stable in contrast to carrot juice and asparagus. Addition of ascorbic acid (0.5 mg/g) in carrot juice resulted in a remarkable protective effect on pressure (500 MPa/60 degrees C/40 min) and temperature degradation (120 degrees C/40 min) of 5-CH(3)-H(4)folate.

Aroma active components in aqueous kiwi fruit essence and kiwi fruit puree by GC-MS and multidimensional GC/GC-O.

Gas chromatography-mass spectrometry (GC-MS) and multidimensional gas chromatography olfactometry (GC/GC-O) were utilized to study the aroma profile and the aroma active components of commercial kiwi essence and the initial fresh fruit puree. Totals of 29 and 33 components were identified and quantified in the essence and the puree, respectively. Ten components were quantified for the first time as constituents of the kiwi fruit including 3-penten-2-ol, 3-hydroxy-2-butanone, 3-methyl-2-butenal, 2-hexanol, nonanal, 3-methyl-1-butanol, 2-methyl-1-butanol, 3-methyl-2-butanone, 3-methyl 3-buten-2-one, and octane. Analysis of these samples by multidimensional gas chromatography-olfactometry (GC-O) allowed for the identification of >80% of the aroma active components present at level traces in this fruit. A total of 35 components appear to contribute to the aroma of kiwi fresh puree and its aqueous essence. Components described for the first time as constituents of the aroma profile in this fruit were 2-ethylfuran, 3-methyl-1-butanol, 2-cyclohexen-1-one, (E,E)-2,6-nonadienal, diethyl succinate, and hexyl hexanoate.

Composition of Italian kiwi (Actinidia chinensis) puree

The composition of the Hayward variety of kiwi from Italy was determined including ash, total solids, soluble solids, pectin, organic acids (quinic, citric, malic, D-isocitric), sugars (glucose, fructose, and sucrose), minerals (Na, K, Ca, Mg, and P), amino acids, and total protein. Liquid chromatographic methodology was used for the separation, identification, and quantitation of sugars, organic acids, and amino acids

GC-FTIR as a powerful tool for the characterization of flavor components in Kiwi

Extracts from deep-frozen Kiwi puree were investigated by an integrated method consisting of GC-FTIR and GC-MS for a reliable identification of the peaks detected and GC-sniffing to correlate this chemical information to sensory impression. Beneath trans-2-hexenal, that is responsible for the fresh, green scent, cyclohexarione was identified among a number of substances. By comparison of the FTIR-spectra to a specific vapor-phase-IR-library, that is presently accumulated in our group, most of the components could be identified. In particular 3 terpene-esters, linalyl-acetate, isobornylacetate anda-terpinyl-acetate were identified and found to be responsible for an overripe, terpene-like-off-flavor in stored Kiwi puree. In this field of unsaturated terpenes, esters and aldehydes the identification-capability of FTIR together with appropriate library-spectra exceeds that of mass-fragmentograms, especially for isomeric compounds, whereas the combined information of both techniques is needed for a reliable characterization of complex flavor-mixtures because of its complementary nature.