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Use of near infrared spectroscopy and chemometrics to evaluate the shelf-life of cloudy sonicated apple juice
摘要： Fresh products, such as cloudy apple juice, could be preserved from early spoilage through the application of non-thermal processes such as sonication. However, shelf-life analyses based on microbiological and sensory evaluations are expensive and time consuming. Few studies have applied near infrared spectroscopy to evaluate the quality and decay of apple juices. Here, a feasibility trial was conducted to study the spectral behaviour at 1300–2500 nm combined with chemometric approaches. The shelf-life was monitored during two experiments, a challenge test with juices inoculated with spoilage yeasts (inoculated non-sonicated (INS)) and then submitted to sonication treatments (inoculated sonicated (IS)), and a storage test to evaluate the spoilage on non-inoculated juices (non-inoculated non-sonicated (NINS)) and sonicated non-inoculated juices (non-inoculated sonicated (NIS)). These experiments were investigated at six different refrigeration times 7, 14, 21, 28 and 60 days. Two functions were modelled to describe the behaviours of the first principal component according to the storage time. In agreement with a previous chemical and sensory evaluation, this approach allowed us to highlight shelf-life end points of 7 and 14 days for non-sonicated and sonicated samples, respectively. Three different models were evaluated for classification purposes: (1) sonicated versus non-treated samples, (2) end-point shelf-life evaluation at seven days for the NINS and INS juices and (3) end-point shelf-life discrimination at 14 days for IS and NIS samples. A partial least square-discriminant analysis enabled a group classification with accuracy values ranging from 0.63 to 1.00. The application of a variable importance in projection index to interpret the wavelengths of the spectral features suggests a contribution of organic acids and lipids to the prediction of decay. A canonical discriminant analysis provided a clearer separation of samples according to the storage time, especially in relation to the two time thresholds of 7 and 14 days.
关键词： Apple juice,spoilage,near infrared spectroscopy,shelf-life,sonication
更新于2025-09-23 15:23:52
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Effects of LED lighting recipes on postharvest quality of leafy vegetables grown in a vertical farm
摘要： Vertical farming is a technology that controls climate, water, nutrients and light to grow food in a closed environment. This allows vegetables to grow pesticide free and without other contaminants. We investigated how to influence the postharvest quality by controlling the preharvest growth conditions while keeping a high production rate. Several standard LED lighting recipes (red/blue or red/white either with or without far red) are in use in commercial farms. For this research we used lettuce, baby leaf spinach, rocket and basil from various cultivars all grown in a vertical farm research facility. We used the standard red white LED light recipe as control, while we changed the spectrum with higher blue and/or higher far-red or apply few days of continuous light stimulation just before the harvest (preharvest). Quality at harvest and quality loss during postharvest storage was monitored. We observed that light quality affects shelf life of baby leaf spinach and rocket by several days. The best light recipe for shelf life had a high blue content (35%) while the worst was with a high far red (25%). In addition, contents of vitamin C, K, nitrate, chlorophyll and flavonols were different under various light quality. Nitrate (in lettuce, rocket and spinach) and vitamin C in rocket were strongly affected by preharvest continuous light, offering a way to reduce the nitrate and improve the antioxidant level. In addition, taste was also found to change as a function of light quality but magnitude of this change is shown to be strongly cultivar dependent.
关键词： LED lighting,nitrate,vitamin K,shelf life,vertical farming,taste,vitamin C
更新于2025-09-16 10:30:52
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Different Postharvest Responses of Fresh-Cut Sweet Peppers Related to Quality and Antioxidant and Phenylalanine Ammonia Lyase Activities during Exposure to Light-Emitting Diode Treatments
摘要： The in?uence of emitting diode (LED) treatments for 8 h per day on functional quality of three types of fresh-cut sweet peppers (yellow, red, and green) were investigated after 3, 7, 11, and 14 days postharvest storage on the market shelf at 7°C. Red LED light (660 nm, 150 μmol m?2 s?1) reduced weight loss to commercially acceptable level levels (≤2.0%) in fresh-cuts of yellow and green sweet peppers at 7 and 11 d, respectively. Blue LED light (450 nm, 100 μmol m?2 s?1) maintained weight loss acceptable for marketing in red fresh-cut sweet peppers up to 11 d. Highest marketability with minimum changes in color di?erence (?E) and functional compounds (total phenols, ascorbic acid content, and antioxidant activity) were obtained in yellow and green sweet pepper fresh-cuts exposed to red LED light up to 7 and 11 d, respectively, and for red sweet pepper fresh-cuts exposed to blue LED light for 11 d. Red LED light maintained the highest concentrations of β carotene, chlorophyll, and lycopene in yellow, green, and red sweet pepper fresh-cuts up to 7 d. Similarly, blue LED light showed the highest increase in lycopene concentrations for red sweet pepper fresh-cuts up to 7 d. Red LED (yellow and green sweet peppers) and blue LED (red sweet pepper) lights maintained phenolic compounds by increasing phenylalanine ammonia lyase activity. Thus, the results indicate a new approach to improve functional compounds of di?erent types of fresh-cut sweet pepper.
关键词： postharvest quality,antioxidant activity,bioactive compounds,photo technology,Capsicum annuum L.,shelf life
更新于2025-09-11 14:15:04