Color analysis of horticultural produces using hue spectra fingerprinting.

Color has great importance in agriculture due to its relationship with plant pigments and therefore, plant development and biochemical changes. Due to the trichromatic vision, instruments equipped with CCD or CMOS sensor represent color with the mixture of red, green and blue signals. These values are often transformed into HSL (hue, saturation, luminance) color space. Beyond average color of the visible surface area, histograms can represent color distribution. Interpretation of distribution can be challenging due to the information shared among histograms. Hue spectra fingerprinting offers color information suitable for analysis with common chemometric methods and easy to understand. Algorithm is presented with GNU Octave code.•Hue spectra is a histogram of hue angle over the captured scene but summarizes saturation instead of number of pixels. There are peaks of important colors, while others of low saturation disappear. Neutral backgrounds such as white, black or gray, are removed without the need of segmentation.•Color changes of fruits and vegetables are represented by displacement of color peaks. Since saturation is usually changing during ripening, storage and shelf life, peaks also change their shape by means of peak value and width.

In-Situ Measurement of Fresh Produce Respiration Using a Modular Sensor-Based System.

In situ, continuous and real-time monitoring of respiration (R) and respiratory quotient (RQ) are crucial for identifying the optimal conditions for the long-term storage of fresh produce. This study reports the application of a gas sensor (RMS88) and a modular respirometer for in situ real-time monitoring of gas concentrations and respiration rates of strawberries during storage in a lab-scale controlled atmosphere chamber (190 L) and of Pinova apples in a commercial storage facility (170 t). The RMS88 consisted of wireless O2 (0% to 25%) and CO2 sensors (0% to 0.5% and 0% to 5%). The modular respirometer (3.3 L for strawberries and 7.4 L for apples) consisted of a leak-proof arrangement with a water-containing base plate and a glass jar on top. Gas concentrations were continuously recorded by the RMS88 at regular intervals of 1 min for strawberries and 5 min for apples and, in real-time, transferred to a terminal program to calculate respiration rates ( R O 2 and R CO 2 ) and RQ. Respiration measurement was done in cycles of flushing and measurement period. A respiration measurement cycle with a measurement period of 2 h up to 3 h was shown to be useful for strawberries under air at 10 °C. The start of anaerobic respiration of strawberries due to low O2 concentration (1%) could be recorded in real-time. R O 2 and R CO 2 of Pinova apples were recorded every 5 min during storage and mean values of 1.6 and 2.7 mL kg-1 h-1, respectively, were obtained when controlled atmosphere (CA) conditions (2% O2, 1.3% CO2 and 2 °C) were established. The modular respirometer was found to be useful for in situ real-time monitoring of respiration rate during storage of fresh produce and offers great potential to be incorporated into RQ-based dynamic CA storage system.

Response of pomegranate arils (cv. Wonderful) to low oxygen stress under active modified atmosphere condition.

BACKGROUND: Successful characterization of the relationship between respiration rate (RR) and low oxygen (O2 ) limit is critical for optimizing the modified atmosphere condition. It is well documented that a low O2 atmosphere reduces the RR of fresh produce, but could also lead to abiotic stress due to the accumulation of glycolysis end products. Therefore, this study investigated the response of pomegranate arils exposed to low O2 atmosphere (composed of 2 kPa O2 , 18 kPa carbon dioxide, and 80 kPa nitrogen) and identified the low O2 limit at 5 °C and 10 °C. The study aim was achieved by using real-time RR and respiration quotient (RQ) data, microbial growth, identifying changes in the fermentative volatile organic compounds profile, and the consumption of respiratory metabolites (organic acids and individual sugars). RESULTS: The gas concentrations changed significantly respective to the storage temperature and resulted in a significant change in the parameters studied. The response of pomegranate arils to low O2 stress involves making alterations to the metabolic composition, especially those involved in anaerobiosis, such as the accumulation of ethanol, and an immediate increase on RQ. CONCLUSION: Pomegranate arils (cv. Wonderful) can tolerate down to 1.9 kPa O2 and 2.3 kPa O2 concentrations at 5 °C and 10 °C respectively. © 2018 Society of Chemical Industry.

Impact of mixtures of different fresh-cut fruits on respiration and ethylene production rates.

UNLABELLED: Packaging and storage of fresh-cut fruits and vegetables are a challenging task, since fresh produce continue to respire and senesce after harvest and processing accelerates the physiological processes. The response on respiration and ethylene production rates of fresh produce to changes in O2 and CO2 concentrations and temperature has been extensively studied for whole fruits but literature is limited on processed and mixed fresh-cut fruits. This study aimed to investigate the effects of mixing various proportions of fresh-cut fruits (melon chunks, apple slices, and pineapples cubes) on respiration and ethylene production rates and to develop predictive models for modified atmosphere packaging. The experiment was designed according to a simplex lattice method and respiration and ethylene production rates were measured at 10 °C. Results showed that single component pineapple cubes, apple slices, and melon chunks, in this order, had significant constant coefficients (P = 0.05) and the greatest impact on respiration rate while the interactive binary and tertiary coefficients were insignificant. For ethylene production rates, single component apple slices, melon chunks, and pineapple cubes, and their 3-component mixtures, in this order, had significant constant coefficients (P = 0.05) while binary coefficients were insignificant. Mathematical models were developed and validated; the cubical model was the best to describe the influence of proportion of fruit on respiration and ethylene production rates, however, considering simplicity the linear part of the model is recommended to quantify respiration and ethylene production rates of mixed fresh-cut fruits. PRACTICAL APPLICATION: This research helps to quantify the ethylene production and respiration rates of multicomponent mixed fresh-cut fruit, which then can be used for packaging design of fresh-cut produce.

Modified Atmosphere Packaging Technology of Fresh and Fresh-cut Produce and the Microbial Consequences-A Review.

Modified atmosphere packaging (MAP) technology offers the possibility to retard the respiration rate and extend the shelf life of fresh produce, and is increasingly used globally as value adding in the fresh and fresh-cut food industry. However, the outbreaks of foodborne diseases and emergence of resistant foodborne pathogens in MAP have heightened public interest on the effects of MAP technology on the survival and growth of pathogenic organisms. This paper critically reviews the effects of MAP on the microbiological safety of fresh or fresh-cut produce, including the role of innovative tools such as the use of pressurised inert/noble gases, predictive microbiology and intelligent packaging in the advancement of MAP safety. The integration of Hazard Analysis and Critical Control Points-based programs to ensure fresh food quality and microbial safety in packaging technology is highlighted.

Modeling the effect of time and temperature on respiration rate of pomegranate arils (cv. "Acco" and "Herskawitz").

Understanding the effect of time and temperature on the respiration rate (RR) of fresh-cut produce, towards the design of a suitable modified atmosphere packaging (MAP) system, requires an adequate mathematical model for prediction of RR as a function of both time and temperature. This study investigated the effect of temperature (5, 10, and 15 °C) and storage time (1 to 5 d) on the RR (R(O2) and R(CO2)) of 2 pomegranate cultivars (cv. "Acco" and "Herskawitz") fresh arils. R(O2) and R(CO2) were 3 to 4 folds significantly higher with increased temperature from 5 to 15 °C and were within the range of 2.51 to 7.59 mL/kg h and 2.72 to 9.01 mL/kg h, respectively, for both cultivars. At 15 °C R(CO2) increased significantly from 8.4 to 25.96 mL/kg h from day 1 to 5, respectively, while at 5 °C R(CO2) changed from 2.9 to 2.05 mL/kg h from day 1 to 5. Temperature had the greatest influence on RR and the interaction of time and temperature also significantly affected R(O2) and R(CO2). The respiratory quotient (RQ) estimated by linear regression was 0.98 at 95% significant level. The dependence of RR on temperature and time was accurately described with a combination of an Arrhenius-type and power equation model for and of fresh pomegranate arils.