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Modified atmosphere packaging (MAP) is a promising approach to extend the storage life of kiwifruit (Actinidia deliciosa) and reduce food waste at retail. To investigate the effect of MAP on maintaining fruit quality during post-storage shelf life, 'Hayward' kiwifruit were stored in MAP or air (perforated polyethylene film) at 1°C 60%–70% RH for 35 days before being repacked in either perforated film (air), a non-perforated (MAP) retail bag or in MAP with an ethylene scrubber (ES) and stored at 20°C 67%–70% RH for 10 days (simulating retail conditions). The atmospheres created by MAP were 12%–15% O2 + 3%–4% CO2 at 1°C and 12%–16% O2 + 7%–10% CO2 at 20°C. MAP reduced kiwifruit softening during coolstorage, and this benefit was maintained during subsequent shelf life. However, MAP in simulated retail conditions benefited only weight loss and SSC. Ethylene was detected only in retail bags with rotten fruit, including one with an ES, suggesting that an ES may not be sufficient to manage ethylene in retail conditions. The application of MAP in retail as a means of reducing fruit losses at the end of the supply chain requires further research attention. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fruit microstructural differences were found among kiwifruit cultivars. [•] Differences in raphide bundles were found among kiwifruit cultivars. [•] Orchard manipulation caused macro, but not microstructural, quality differences. [ABSTRACT FROM AUTHOR]

Abstract: The kiwifruit industry was established on fruit of Actinidia deliciosa (‘Hayward’), which is known as a climacteric fruit with high sensitivity to ethylene. In recent times fruit from Actinidia chinensis have become a substantial component of the kiwifruit market. There is limited information about the sensitivity of A. chinensis to ethylene during refrigerated storage and hence current ethylene management practices for A. chinensis mimic those established for A. deliciosa. This research aimed to quantify the effect of ethylene during refrigerated storage on A. chinensis (‘Hort16A’) quality (firmness, colour and total soluble solids). Three grower lines were stored at 1.5°C, 95% RH with ethylene in the range of 0.001–1μLL−1 applied to the environment after 3 weeks of storage for the remainder of storage (17 weeks). Fruit quality was assessed at regular intervals. Loss of firmness was found to be very sensitive to ethylene, with significant differences between fruit stored in 0.001μLL−1 (as a control) and 0.1μLL−1 occurring after 2 weeks of exposure. Fruit exposed to 1μLL−1 ethylene not only rapidly softened, but also increased in hue angle (greenness) and reduced in lightness (darkened) further reducing the quality of the yellow coloured kiwifruit cultivar. Total soluble solids were not heavily influenced by ethylene exposure, with grower differences being maintained throughout the experiment. This work demonstrates that A. chinensis (cv. Hort16A) fruit firmness and colour will be influenced by the ethylene conditions in a commercial storage environment by advancing ripening and senescence. [Copyright &y& Elsevier]

Temperature and exogenous ethylene are two important factors that determine the rate of quality change in ‘Hass’ avocado. The aim of this study was to quantify this effect and to build a mathematical model that will assist in predicting the effect of temperature, exogenous ethylene, and time on quality outcomes of ‘Hass’ avocado. A mathematical model was developed to describe autocatalytic ethylene production, and coupled to models describing softening and colour changes via ethylene. The effect of exogenous ethylene was incorporated by addition of a diffusion term, while temperature effect was modelled by expressing rate constants as a function of temperature using the Arrhenius equation. The model was calibrated using data on ethylene efflux rate, firmness and skin hue collected on ‘Hass’ avocado fruit stored at 5, 10, or 20 °C, in atmospheres containing <0.05 μL L −1 (air), 1 μL L −1 or 10 μL L −1 ethylene in air. Effect of ethylene on softening was greater than on colour change, with clear firmness separation of the different ethylene treated fruit evident even during ripening at 20 °C. The high dependency of softening on ethylene was revealed in the Michaelis-Menten constant for the regulation of the softening enzyme by ethylene, which was about 15 times larger than that for the colour degrading enzymes. The model was successfully validated on a sub-dataset. [ABSTRACT FROM AUTHOR]

Hand-feel touch firmness is a sensory method reported to be used by the blueberry industry to characterise individual fruit firmness quality. A 'soft' blueberry may be considered unmarketable. However, firmness assessed by a hand touch is questionable due to being highly influenced by the assessor's subjective judgment. Objective instrumental methods are preferred to measure firmness and create a reliable and consistent dataset. This research aimed to study the relationship between sensory hand-feel touch firmness measured by a trained sensory panel and instrumental mechanical parameters of blueberry 'Centurion'. To our knowledge, this is the first attempt to relate instrumental mechanical parameters to hand firmness using a sensory panel setting and reference samples to exemplify hand-feel intensity differences. Seven assessors were trained to evaluate hand touch firmness in a sensory panel setting. References samples resembling a blueberry were made of silicone and used to calibrate assessors' performance by exemplifying four blueberry firmness scores ('very soft', 'soft', 'firm' and 'very firm'). Six sensory sessions were conducted, where each session represented a harvest date and storage time combination (3 harvest dates X 2 storage times). Each sensory session considered blueberries exposed to five storage relative humidity (71 %, 88 %, 95 %, 97 % and 100 % RH). As a result, assessors were able to discriminate differences in hand touch firmness as influenced by storage relative humidity (water loss differences). In addition, mechanical parameters measured by the slope of force-deformation curve using a plate probe on a compression test (hardness slope) or a needle probe on a penetration test (skin break slope) were best related to sensory hand-feel firmness. Average hardness slope and skin break slope higher than 1.7 kN m−1 and 0.42 kN m−1, respectively, were associated with a very low (≤5 %) likelihood of observing unmarketable ('soft' + 'very soft') 'Centurion' blueberries in a batch. Our study provides a basis for the standardisation of mechanical methods that can be used to assess blueberry quality based on its ability to represent consumer sensation preferences of texture. • A sensory panel was used to evaluate hand-feel touch firmness. • Water loss induces textural changes perceived by hand-feel firmness. • Chord stiffness correlates to hand-feel firmness. • Instrumental values were linked to unmarketable blueberries. [ABSTRACT FROM AUTHOR]

Total soluble solids concentration (TSS) and flesh firmness (FF) are two important quality attributes indicating the eating quality and postharvest storability of kiwifruit. Prediction of TSS and FF using non-destructive techniques would allow strategic marketing of fruit. This paper investigates the ability of visible-near-infrared (Vis-NIR) spectroscopy utilised as a sole input at harvest, to quantitatively predict both TSS and FF after cool storage using a blackbox model. Four at-harvest Vis-NIR spectral and post-storage fruit quality data sets were collected during 2012–2013, in order to develop regression models using partial least squares (PLS) and support vector machines (SVM). The SVM models performed better than PLS. Predictive accuracy was fair to good for TSS (R 2 = 0.58–0.83; RMSE = 0.66–1.02 °Brix) and was poor to moderate for FF (R 2 = 0.30–0.60; RMSE = 2.65–4.32 N). The ratio of prediction deviation, SDR values (1.5–2.3 for TSS; 1.4–1.7 for FF) suggest the developed regression models are not as yet useful for online sorting purposes. [ABSTRACT FROM AUTHOR]

Firmness is an important parameter for fresh blueberries as it influences the quality perceived by consumers and postharvest storage potential. However, the blueberry research community has not yet identified a universal standard method that can evaluate firmness for quality purposes. Different mechanical tests have been considered, offering different perspectives on this quality trait. This review summarises the most common methods previously used to evaluate textural and mechanical properties of fresh blueberries as influenced by pre- and postharvest factors. In addition, this review intends to assist the blueberry research community and commercial supply chain when selecting suitable methods to measure blueberry firmness as a fruit quality response. Different research initiatives to develop, optimize or standardise instrumental methods to assess blueberry firmness and relate to consumer sensory perception are reviewed. Mechanical parameters obtained by compression tests are the most previously used techniques to evaluate the influence of genotype, maturity, calcium, and postharvest management on blueberry firmness or to relate to sensory descriptors. However, standardising operational settings (e.g., compression distance, loading speed, and calculation procedures) is required to make results comparable across data collection conditions. Whether other mechanical test methods such as penetration or a combination of tests can better characterise blueberry quality or the relationship with consumer acceptance remains unknown and is worth studying. • A universal standard method to measure blueberry firmness is absent. • Compression test has been the preferred method to measure blueberry firmness. • Genotype, maturity, calcium, and postharvest management influence blueberry firmness. • Relationship between mechanical parameters and consumer acceptance is required. [ABSTRACT FROM AUTHOR]

Kiwifruit are often harvested unripe and kept in local coolstores for extended periods of time before being marketed. Many pre-harvest factors contribute to variation in fruit quality at harvest and during coolstorage, resulting in the difficulty in segregating fruit for their storage potential. The ability to forecast storage potential, both within and between populations of fruit, could enable segregation systems to be implemented at harvest to assist with inventory decision making and improve profitability. Visible-near infrared (Vis-NIR) spectroscopy is one of the most commonly used non-destructive techniques for estimation of internal quality of kiwifruit. Whilst many previous attempts focused on instantaneous quantification of quality attributes, the objective of this work was to investigate the use of Vis-NIR spectroscopy utilised at harvest to qualitatively forecast storage potential of individual or batches of kiwifruit. Commercially sourced 'Hayward' kiwifruit capturing large variability of storability were measured non-destructively at harvest using Vis-NIR spectrometer, and then assessed at 75, 100, 125 and 150 days after coolstorage at 0 °C. Machine learning classification models were developed using at-harvest Vis-NIR spectral data, to segregate storability of kiwifruit into two groups based on the export FF criterion of 9.8 N. The best prediction was obtained for fruit stored at 0 °C for 125 days: approximately 54% of the soft fruit (short storability) and 79% of the good fruit (long storability) could be predicted. Further novelty of this work lies within an independent external validation using data collected from a new season. Kiwifruit were repacked at harvest based on their potential storability predicted by the developed model, with the actual post-storage performance of the same fruit assessed to evaluate model robustness. Segregation between grower lines at harvest achieved 30% reduction in soft fruit after storage. Should the model be applied in the industry to enable sequential marketing, significant costs could be saved because of reduced fruit loss, repacking and condition checking costs. • At-harvest Vis-NIR data were used to predict postharvest kiwifruit storability. • Classification models enabled qualitative forecast of kiwifruit storage potential. • External validation was conducted by creating segregated populations at harvest. • At-harvest segregation between batches resulted in 30% reduction of soft fruit. [ABSTRACT FROM AUTHOR]