A Handheld low-mass, impact instrument to measure nondestructive firmness of fruit

A portable, handheld impact firmness sensor was designed for nondestructive measurement of fruit firmness while the fruit remain attached to the tree or for use in other remote locations where the use of a benchtop instrument would be impractical. The instrument design was based on the low-mass, constant velocity, impact-type measurement concept. Validation tests of the handheld sensor using `Bartlett' pears from orchards in California and Washington showed excellent agreement (r2 = 0.92 and 0.96, respectively) with both ASAE Standard method S368.2 for determining the apparent modulus of intact fruit and the impact firmness scores from a commercial benchtop impact firmness instrument

Addressing potential sources of variation in several non-destructive techniques for measuring firmness in apples

Measurements of firmness have traditionally been carried out according to the Magness Taylor (MT) procedure; using a texture analyser or penetrometer in reference texture tests. Non-destructive tests like the acoustic impulse response of acoustic firmness sensors (AFSs), a low-mass impact firmness sensor Sinclair International (SIQ-FT) and impact test (Lateral Impact – UPM) have also been used to measure texture and firmness. The objectives of this study were to evaluate the influence of different sources of variation in these three non-destructive tests and to evaluate their respective capabilities of discriminating between fruit maturity at two different harvest dates, turgidity before and after dehydration treatment and ripening after different storage periods. According to our results, fruit studied an unexpected AFS trend with turgidity. Contact measurements (Lateral Impact – UPM and SIQ-FT) appeared highly sensitive to changes in turgidity, but were less able to follow changes in ripening caused by storage period. Contact measurements were suitable for detecting differences between fruits from different harvest dates and showed higher correlation coefficients with reference texture tests than acoustic measurements. The Lateral Impact – UPM test proved better at separating fruits according to turgidity than the SIQ-FT instrumen

Selection Models for the Internal Quality of Fruit, based on Time Domain Laser Reflectance Spectroscopy

Time domain laser reflectance spectroscopy (TRS) was applied for the first time to evaluate internal fruit quality. This technique, known in medicine-related knowledge areas, has not been used before in agricultural or food research. It allows the simultaneous measurement of two optical characteristics of the sample: light scattering inside the tissues and light absorption. Models to estimate non-destructively firmness, soluble solids and acid contents in tomato, apple, peach and nectarine were developed using sequential statistical techniques: principal component analysis, multiple stepwise linear regression, clustering and discriminant analysis. Consistent correlations were established between the two parameters measured with TRS, i.e. absorption and transport scattering coefficients, with chemical constituents (soluble solids and acids) and firmness, respectively. Classification models were created to sort fruits into three quality grades (‘low’, ‘medium’ and ‘high’), according to their firmness, soluble solids and acidity

Detection of internal quality in kiwi with time-domain diffuse reflectance spectroscopy

Time-domain diffuse reflectance spectroscopy (TRS), a medical sensing technique, was used to evaluate internal kiwi fruit quality. The application of this pulsed laser spectroscopic technique was studied as a new, possible non-destructive, method to detect optically different quality parameters: firmness, sugar content, and acidity. The main difference with other spectroscopic techniques is that TRS estimates separately and at the same time absorbed light and scattering inside the sample, at each wavelength, allowing simultaneous estimations of firmness and chemical contents. Standard tests (flesh puncture, compression with ball, .Brix, total acidity, skin color) have been used as references to build estimative models, using a multivariate statistical approach. Classification functions of the fruits into three groups achieved a performance of 75% correctly classified fruits for firmness, 60% for sugar content, and 97% for acidity. Results demonstrate good potential for this technique to be used in the development of new sensors for non-destructive quality assessment

Influence of cold storage time on the softening prediction in Spring Bright nectarines

With Time-resolved Reflectance Spectroscopy (TRS) the maturity of nectarines at harvest can be assessed by measuring the absorption coefficient at 670 nm (µa 670) in the fruit flesh. A kinetic model has been developed linking the optical properties as measured by TRS with the models of µa 670 and firmness decay in shelf-life at 20°C, making the prediction of the softening time for individual fruit possible. In order to study the influence of cold storage time prior to shelf life on the softening prediction, 540 (year 2003) and 870 (year 2004) ‘Spring Bright’ nectarines were measured at harvest with TRS; then fruit were put in shelf life after various periods of cold storage at 0°C (4 and 10 d, year 2003; 6, 13 and 20 days, year 2004). During the 5-day period of shelf life at 20°C, fruit were analysed for firmness by pressure test after 30, 48, 54, 72, 78, 96, 102 and 120h in 2003 and after 36, 43, 62, 87, 108 and 135h in 2004. For each year and cold storage time, the parameters of the logistic model of softening as a function of µa 670 at harvest were computed. The cold storage up to 13 days did not significantly influence the estimates of the softening rate constant (kf), of the maximum firmness at minus infinite time (Fmax) and of parameter alpha (a) in both years, whereas parameter beta (ß) in 2003 significantly decreased from -1.867 at day 4 to -2.237 at day 10. The further 7 days of cold storage in 2004 significantly affected kf, which decreased from 0.00084 at days 6 and 13 to 0.00069 at day 20, and ß which increased from -2.395 at day 6 to -2.053 at day 20. Our results indicate that the cold storage time significantly influences the softening prediction of nectarines as the longer the cold storage, the lower the softening rat

Variation in the impact of stem scar and cuticle on water loss in highbush blueberry fruit argue for the use of water permeance as a selection criterion in breeding

The role of fruit scar on water loss from fresh harvested, fully blue highbush blueberry (Vaccinium corymbosum L.) fruit was studied on three germplasm lines from each of three half-sib families at University of Talca, Chile. The stem scar of half of the harvested fruit was sealed using nail polish and weight loss of sealed and non-sealed fruit determined daily at 20 °C (5 d storage) and bi-weekly at 0 °C (15 d storage). Fruit firmness was determined at the end of the storage period. The stem scar accounted for approximately 40% of the moisture lost at 20 °C, but percentages varied considerably between lines. While the stem scar covered 0.19% to 0.74% of the fruit surface area, its rate of transpiration was 170-times higher than for the cuticle at 20 °C. The larger the fruit scar area, the greater was the absolute rate of water loss, but scar size scar did not affect the rate of weight loss expressed on a per gram fruit basis. Higher levels of water loss were associated with a greater loss in firmness; fruit having a large scar had a greater rate of water loss and were less firm than those having medium or small scars. The water permeance of the fruit cuticle varied two-fold and the apparent permeance of the scar varied three-fold among the 9 lines evaluated when held at 20 °C. Interestingly, one line exhibited a 75% lower rate of water loss from its stem scar than the other lines than would be predicted based on its scar diameter. Storage at 0 °C reduced the rate of water loss by 90% but the cuticle permeance was not affected by temperature. Sealing the stem scar increased fruit firmness retention at 0 °C and 20 °C, but provided less benefit at 0 °C vs. 20 °C. The highly variable nature of water loss through the stem scar and the cuticle in this study suggests that large gains in reductions in water loss are possible for the highbush blueberry once the mechanisms for transpiration are better understood.In Chile, this work was supported by the National Commission for Scientific and Technological ResearchCONICYT (FONDECYT11130539) and the Universidad de Talca (research programs “Adaptation of Agriculture to Climate Change (A2C2)”, “Fondo Proyectos de Investigación” and “Núcleo Científico Multidisciplinario”). In the United States this work was partially supported by the “2015 Fulbright Specialist Program”, Project 6365. In Spain this work was partially supported by “Fundación Carolina” and “Programa de Doctorado en Ciencia y Tecnología Agraria y Alimentaria”, Universitat de Lleida

A First approach of using ultrasound as an alternative for blanching in vacuum-packaged potato strips

The effect of ultrasound (US) (40 kHz, 200 W, 3 min), blanching (85 °C, 3.5 min), and the combination of both methods was evaluated on the quality of vacuum-packaged potato strips stored at 3 ± 1 °C for up to 10 days. For this study, two cultivars of potatoes were assessed. For blanched Agata samples, the lightness (L*) decreased over 12 % (p < 0.05). Moreover, their hue increased up to 100, obtaining lesser yellow potato strips. In contrast, US did not affect the hue values. The losses of firmness of blanched potato strips were notable (35 % for Agata and 51 % for Agria), whereas US did not change this property (p < 0.05). Nevertheless, no significant differences were found in the total starch content at 10 days. Agata and Agria showed different metabolic behaviors of sucrose in the refrigerated storage. Therefore, Agria cultivar retained better color after frying. These results suggest that US had less impact on color and improve the firmness in vacuum-packaged potato strips with no added chemicals.Postprint (author's final draft

Investigation of the Role of Plasticizers in Film-forming Coats for Protecting Cooled Meat

As a result of theoretical studies on problems of protection and prolongation of storage terms of meat, it was revealed, that one of promising directions is to use protecting coats, based on natural biopolymers.The topicality of this study is in studying film-forming coats, based on natural polysaccharides, because they have high mechanical indices, absence of a smell, taste and are subjected to biological destruction. For regulating mechanical properties, the composition of film-creating coats is added with plasticizers of different origins.The aim of this work is in describing characteristics of food films, based on carrageenan, sodium alginate and plasticizers of different origins.There were mechanical, rheological properties of protecting coats. The comparative characteristic of these properties, depending on an added plasticizer, was realized. The type and mechanisms of interaction of components of the film-forming coat and plasticizers were completely described. The viscosity of the film-forming coat with a plasticizer has less values comparing with other solutions. Adding plasticizers resulted in increasing the film elasticity, but at the same time some increase of the firmness was observed.Film-forming coats with adding a plasticizer had a higher limit of fluidity, so they were firmer than complex film-forming coats without a plasticizer. From the other side, deformation values of film-forming coats without adding a plasticizer were higher than ones of complex film-forming coats with adding a plasticizer, because they were firmer.The study of physical properties of developed film-forming coats, based on hydrocolloids, demonstrated that coats with a plasticizer have more gas permeability.According to the results, obtained at experiments it was established, that the film-forming coat, based on sodium alginate, carrageenan and glycerin, has best mechanical, physical and rheological indices