‘Annurca’ apple fruit,a southern Italy apple cultivar: textural properties and aroma composition

‘Annurca’ apple fruit, which is commonly cultivated in southern Italy and undergoes a typical reddening treatment and, is notable for its high firmness and its characteristic flavour, was examined for its pectic and aroma composition. Pectin, extracted with a water solution of potassium oxalate and dimethylsulphoxide, was found to be quantitavely and qualitatively important for its contribution to the high tissue firmness. Pectin changes its composition during the reddening process and there is even a difference in the pectic composition of the two ‘Annurca’ clones examined in this paper, ‘Standard’ and ‘Rossa del Sud’. Volatile compounds were collected by headspace sampling of intact unreddened and reddened fruits. Thirty-one compounds of several chemical classes were identified, to establish their role in the characteristic flavor of this apple cv. Among these compounds, n-pentanol was unusually present in large amounts; also δ-octalactone, never found in apples, was present.     

Design of apple snacks – A study of the impact of calcium impregnation method on physicochemical properties and structure of apple tissues during convective drying

Calcium impregnation methods (at atmospheric pressure, AI, or under vacuum, VI) followed by air drying at 60 °C were used for producing healthy apple snacks. This study compared the effect of the impregnation method on the ultrastructure features and physicochemical properties (desorption isotherm, density, porosity and shrinkage, thermal transitions, rheological behaviour, colour) of fortified apples along convective drying. Calcium concentration in AI and VI dried apples were ≈ 3600 and ≈ 5200 ppm respectively, which implied, considering a portion of dried apple of 50 g, 18% and 26% of the recommended intake for adults. Calcium incorporation did not affect the desorption behaviour but induced browning of apple tissues. Drying resulted in a great increase in porosity of AI samples and a noticeable compaction of the VI tissues. Impregnated tissues at a_w ≤ 0.47 exhibited distinctive mechanical properties: AI apples were characterized by very high stiffness and lower resistance to rupture, while VI apples appeared stronger and moderately stiff.Industrial relevance textThis study will help to develop large-scale commercial production of calcium fortified apple snacks with distinctive characteristics. High quality and content of nutrients, easy industrialization and storage and a long shelf life are important aspects of these healthy snacks. They constitute a valuable functional shelf-stable product, that also can help feeding the population during natural disasters and wars, as well as reducing food insecurity in vulnerable groups as part of the diet. On the other hand, the use of apples not meeting the organoleptic requirements for direct consumption, or not processed into juice, drink, or cider as raw material, looks of particular interest for diversifying the production within the framework of sustainable production.     

Stability of antioxidants in an apple polyphenol–milk model system

The stability of antioxidants in an apple polyphenol–milk model system was examined. The model system consisted of skim milk fortified with pH-neutralised apple polyphenols (AP, 0–200 mg per 100 ml milk), with or without ascorbic acid (100 mg per 100 ml milk). Physical and chemical changes were evaluated after thermal treatment (120 °C, 5 min) and oxidative storage (20 °C and 38 °C, up to 12 weeks). Antioxidant capacity was determined using both oxygen radical absorbance capacity (ORAC) assay and ferric reducing antioxidant power (FRAP) assay. Significant antioxidant capacity was detected in the presence of milk. Antioxidant capacity was retained during thermal treatment but decreased slowly during storage.     

The effects of γ irradiation on the structure of apple pectin

The effects of γ irradiation on the mol. wts, viscosities and methoxyl contents of apple pectins were investigated at doses of 0–10 kGy. The apple pectins investigated were samples isolated in the laboratory before and after irradiation and an industrially purified apple pectin. No changes in mol. wts of the pectins were observed when whole apples were irradiated but decreases in viscosity and methoxyl content were observed at doses of 1 kGy. When isolated pectins were irradiated, reductions also in mol. wt were detected, at the same doses.     

Inactivation of Alicyclobacillus acidoterrestris spores by high pressure CO₂ in apple cream

Alicyclobacillus acidoterrestris (A. acidoterrestris) is a bacillus-type spore former that causes significant alterations in fruit products. It is highly resistant to typical pasteurization regimes; thus, this work explored the use of high-pressure CO? (HPCD) for its deactivation in apple cream. The assays were conducted in a high-pressure apparatus where the cream was placed in an agitated vessel and the CO? passed over under different operating conditions for distinct periods of time. The HPCD was able to deactivate the A. acidoterrestris spores in the apple cream by four orders of magnitude at 30 °C and 10 MPa. On the other hand, the lethal effect of HPCD was independent of the thermal effect since the application of dry heat without CO? at the same temperature did not cause any A. acidoterrestris deactivation. The important variables in terms of improving the method were the flow regime and the way to put in contact the HPCD and the cream. Finally, the HPCD treatment did not affect the most important sensorial and rheological properties of the cream; although there was a slight reduction in the vitamin C content due to thermal degradation.     

The optimisation of solid–liquid extraction of antioxidants from apple pomace by response surface methodology

Response surface methodology using two food grade solvents, acetone and ethanol, was used to optimise antioxidant extraction from industrially generated apple pomace. Efficiency of extraction was optimised by measuring antioxidant activity, phenol content and three individual polyphenol groups. Conditions for optimal antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay were 56% ethanol, 80 °C and 31 min. Using these conditions an antioxidant value of 444 mg Trolox/100 g DW was obtained. For acetone extraction the optimal conditions were 65% acetone, 25 °C and 60 min, resulting in an antioxidant value of 436 mg Trolox/100 g DW. Both ethanol and acetone would be suitable to replace methanol for a food grade and more environmental friendly solid–liquid extraction of antioxidants.     

Solid-state fermentation of apple pomace using Phanerocheate chrysosporium – Liberation and extraction of phenolic antioxidants

Apple pomace is a by-product from the apple processing industry and can be used for the production of value-added phenolic compounds. A study was carried out to understand the changes and liberation of phenolic compounds and improvement in antioxidant activity during solid-state fermentation of apple pomace using Phanerocheate chrysosporium. The solid-state fermentation of apple pomace using P. chrysosporium mobilised the polyphenolic compounds and improved the nutraceutical properties. The polyphenol content in acetone extract increased and the results were statistically significant (P < 0.05) from 4.6 to 16.12 mg GAE/g dry weight during solid-state fermentation. The effect of various solvents, temperature, time and detergents were also investigated for the extraction of polyphenolics by ultrasonication and microwave-assisted extraction methods. The polyphenol content of the extracts was found to be in the range of 5.78–16.12 mg GAE/g DW of samples, depending on the solvent, extraction time and temperature. Antioxidant activities of polyphenol extracts were tested using the 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods, where the IC₅₀ ranged from 12.24 to 23.42 μg DW sample, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations.     

Characterization of traditional and exotic apple varieties from Portugal. Part 2 – Antioxidant and antiproliferative activities

Apples are known to have many health-promoting activities, especially anticancer, antiradical and antioxidant effects. Most of these actions are believed to be due to their polyphenolic components which vary greatly between different varieties.In this work, four traditional Portuguese apple cultivars (Bravo de Esmolfe, Malápio Fino, Malápio da Serra and Pêro Pipo) and five exotic varieties (Golden, Starking, Fuji, Gala Galaxy and Reineta Parda) were evaluated in terms of their bioactivity using both cell-based and cell-free assays; 17 parameters were evaluated for each sample. Results obtained were submitted to principal component analysis (PCA) and it was possible to conclude that Malápio Fino and Bravo de Esmolfe apple varieties have the highest antioxidant effect and Reineta Parda variety is the best cultivar in promoting antiproliferative effect against human colon (HT29) and gastric (MKN45) cancer cells. Correlations of the data obtained showed that among phenolic compounds catechin, epicatechin and procyanidin B1 were the major contributors to the antioxidant activity of apples whereas procyanidins (B1 and B2), phloridzin and epicatechin played an important role against human cancer cell proliferation.     

Studies on apple and blueberry fruit constituents: do the polyphenols reach the colon after ingestion?

The aim of our studies was to determine the amount of polyphenols reaching the colon after oral intake of apple juice and blueberries. After a polyphenol-free diet healthy ileostomy volunteers consumed a polyphenol-rich cloudy apple juice while others consumed anthocyanin-rich blueberries. Ileostomy effluent was collected and polyphenols were identified using HPLC-DAD as well as HPLC-ESI-MS/MS; quantification was performed with HPLC-DAD. Most of the orally administered apple polyphenols were absorbed from or metabolized in the small intestine. Between 0 and 33% of the oral dose was recovered in the ileostomy bags with a maximum of excretion after 2 h. A higher amount of the blueberry anthocyanins under study (up to 85%, depending on the sugar moiety) were determined in the ileostomy bags and therefore would reach the colon under physiological circumstances. Such structure-related availability has to be considered when polyphenols are used in model systems to study potential preventive effects in colorectal diseases.     

Measurement of malonaldehyde in apple juice using GC–MS and a comparison to the thiobarbituric acid assay

Malonaldehyde (MA) in gamma-irradiated apple juice was measured using a GC–MS method and in comparison to the thiobarbituric acid (TBA) assay. The profiles of MA content as a function of radiation dose were similar using both methods, however, MA content was higher when measured with the TBA assay compared to the GC–MS method. The overestimation of MA using the TBA assay increased as the amount of MA decreased. Use of the GC–MS method demonstrated MA content in irradiated juice declined rapidly during storage at 5 °C. MA content appeared to decrease much less when the TBA assay was used. The GC–MS method also allowed measurement of formaldehyde and acetaldehyde in addition to MA.     

Characterization of traditional and exotic apple varieties from Portugal. Part 1 – Nutritional,phytochemical and sensory evaluation

Phytochemical and nutritional characterization of traditional (Bravo de Esmolfe, Malápio Fino, Malápio da Serra, and Pêro Pipo) and exotic (Golden, Starking, Fuji, Reineta Parda and Gala Galaxy) apple varieties from Portugal were performed. Measurements were taken on 43 parameters including water, protein, sugars, acids, fibre, vitamins (C, A,B1, B2, B3, B5, B6, B9, β-carotene and α-tocopherol), minerals (K, P, Mg, Ca, S, Na, Si, B, Fe, Al, Cu, Mn, Zn, Ni, Mo, Cd) and polyphenols (total, catechin, epicatechin, chlorogenic acid, phloridzin, quercetin-3-glucoside, quercetin-3-rhamnoside, kaempferol-3-glucoside, procyanidins B1 and B2). Nutritional composition results showed that traditional apples had higher contents of fibre, protein, sugars, β-carotene, vitamin E, Mg and phenolic compounds. A comparison between unpeeled and peeled apples was also performed for the Bravo de Esmolfe variety and the unpeeled apples had higher amounts of fibre. Results from sensory evaluation of traditional apples performed by selected assessors and consumers showed there were differences among sample attributes such as sourness, juiciness and hardness, and two apple varieties were preferred (Bravo de Esmolfe and Pêro Pipo) for their odour, taste, hardness and juiciness.     

Freeze-dried snacks obtained from frozen vegetable by-products and apple pomace – Selected properties,energy consumption and carbon footprint

Valorisation of food waste is one of the goals that food industry needs to achieve in terms of sustainable development. The aim of the research has been to analyse selected properties of freeze-dried vegetable snacks obtained from wholesome waste derived from the fruit and vegetable industry, such as frozen vegetable by-products and apple pomace as well as to estimate carbon footprint as the technological process output on the basis of the energy used for the purpose of producing snacks. Properties of snacks, such as water content and activity, shrinkage, density, porosity and hardness, were determined using common methodology. The water content of the finished products was very low (<1.5%) and determined the water activity below 0.02. Technological operations, such as grinding, caused destruction of the cell structure of the ingredients, which subsequently made the product structure inhomogeneous and more dense than most of the freeze-dried plant tissues. The snacks were porous and featured by hardness of 79.43–113.26 N. The colour depended on their composition, and freeze-drying caused the products to brighten significantly. The estimated carbon footprint (CF) depended on the technological process. Freeze-drying had the most significant impact upon the CF, accounting for 86–87%. The use of apple pomace powder as a structure- and texture-forming additive constitutes the subject matter representing great prospects for further research.     

Development of a bioassay-coupled HPLC-SPE-ttNMR platform for identification of α-glucosidase inhibitors in apple peel (Malus ×domestica Borkh.)

This work describes an analytical platform based on a high-resolution α-glucosidase inhibition assay in combination with hyphenation of high-performance liquid chromatography, solid-phase extraction, and tube-transfer nuclear magnetic resonance spectroscopy, i.e., HPLC-SPE-ttNMR/high-resolution α-glucosidase assay. The platform enables fast screening for individual α-glucosidase inhibitory analytes in complex matrices, followed by structural identification targeted these α-glucosidase inhibitors, as demonstrated by a proof-of-concept study with extract of 'Pink Lady' apple peel. A scout-separation produced a high-resolution biochromatogram and a HPLC chromatogram, which were used for pinpointing HPLC peaks displaying α-glucosidase inhibition. Active analytes were cumulatively trapped on SPE cartridges and the structures identified by (1)H NMR experiments obtained in the HPLC-SPE-ttNMR mode. (-)-Epicatechin (1), reynoutrin (3) and avicularin (4) were identified as active compounds. IC(50) of the active compounds were determined along with six structurally related compounds. Quercetin was the most potent inhibitor with an IC(50) of 8.1±0.4μM. The platform proved to be an efficient method for the identification of α-glucosidase inhibitors.     

Analysis of patulin in apple products by liquid–liquid extraction,solid phase extraction and matrix solid-phase dispersion methods: a comparative study

Patulin is a marker of quality in the apple and apple juice industry and due to the potential risk for human health, reliable and potential methods for extracting patulin from a sample are therefore needed. In this study, the three methods with liquid–liquid extraction, matrix solid-phase dispersion (MSPD) and with solid-phase extraction (SPE) were studied for extracting patulin from different apple products. Result showed that for AJC and apple sample, MSPD method is most suitable for extracting patulin among the three methods. The recovery rates of AJC and apple sample were 80.35–114.46 and 79.68–94.32%, respectively, the coefficient variations were 3.18–4.90%; For dilute juice, SPE procedure is suitable for analysis of patulin and the recovery rates were and 85.35–90.14%.     

Determination of patulin in apple and quince products by GC–MS using C5–7 patulin as internal standard

A reliable gas chromatographic mass spectrometric method has been validated for the determination of trace levels (<10 μgL⁻¹) of patulin in apple products and quince jam. The method was based on extraction of patulin with ethyl acetate-hexane, alkalinisation and silylation with N,O-bis-trimethylsilyltrifluoroacetamide with 1% of trimethylchloro-silane. The accurate determination of patulin was achieved by employing commercial ¹³C_5–7 patulin labelled as an internal standard, which allowed compensating target analyte losses and enhancement or suppression matrix effects. Limits of detection and quantification of method using real samples were 0.4 and 1.6 μgkg⁻¹, respectively. Recoveries of patulin from samples spiked at 8–50 μgkg⁻¹ levels ranged between 71% and 89%. The repeatability of measurements (expressed as relative standard deviation) was lower than 16%. The method was successfully applied to the determination of patulin in apple fruit and apple products including juice, cider and baby food, and also in quince fruit and quince jam. A new PCR system for the detection of Penicillium expansum in samples containing highly degraded DNA was developed which permitted the detection of the mould in 2/3 of the samples containing patulin, including juices and jams.     

Dessert and crab apple seeds as a promising and rich source of all four homologues of tocopherol (α, β, γ and δ)

Tocochromanols composition in apple seeds, obtained as a by-product during the fruit salad and juice production, of twelve varieties - seven crab apple (‘Kerr’, ‘Kuku’, ‘Quaker Beauty’, ‘Riku’, ‘Ritika’, ‘Ruti’ and K-8/9-24) and five dessert apples (‘Antej’, ‘Beforest’, ‘Kent’, ‘Sinap Orlovskij’ and ‘Zarja Alatau’) were studied. Tocopherols and tocotrienols were isolated using the micro-saponification method of high precision and accuracy and they were analysedanalysed by rapid RP-HPLC/FLD and RP-UPLC-ESI/MSⁿ. Four tocopherols, with predominance of homologues α and β, were detected in each tested sample. The seeds from two apple cultivars ‘Antej’ and ‘Beforest’ were characterized by unique and similar ratios of all four tocopherol homologues α:β:γ:δ (1.7:1.5:1.3:1.0 and 2.1:2.0:1.3:1.0, respectively). The concentration range of individual tocopherol homologues (α, β, γ and δ) in apple seeds were as follows: 17.22–25.79, 7.53–29.05, 0.61–13.82 and 0.16–10.79 mg/100 g dry weight basis (dwb), respectively. Moreover, three tocotrienols (α, β and γ) were identified in lesser amounts (0.02–0.74 mg/100 g dwb). Use of apple seeds to isolate tocopherol homologues can ensure better environmental sustainability and effective use of natural plant material.     

Effects of an evoked refreshing consumption context on hedonic responses to apple juice measured using best–worst scaling and the 9-pt hedonic category scale

Awareness of the need to consider a product’s consumption context when measuring consumer hedonic response of a product is increasing among consumer sensory researchers. This study investigated the effects of evoking a consumption context using a written scenario on hedonic response measured using best–worst scaling and the 9-pt hedonic category scale. Hedonic responses for four apple juices with relatively large sensory differences were compared when measured in the evoked context ‘when having something refreshing to drink’ using best–worst hedonic scaling (n = 65) and the 9-pt hedonic scale (n = 48). Best–worst scaling discriminated between the four apple juices when a refreshing context was evoked (p < 0.01), while the juices were equally liked using the 9-point scale (p = 0.41) when the same context was evoked. Consumers perceived best–worst scaling to be more difficult than the 9-pt scale, however there was no difference between the two methods for consumers perceived accuracy of their liking information. The present study highlights that the effect of an evoked context on hedonic response may not be universal for hedonic methods. Further research is needed to understand the effect of evoking context on the liking of products, and to determine whether this measure reflects product liking in an actual consumption context.