Fresh Pepper Research Articles

HS–SPME combined with GC–MS and GC–O for characterization of key aroma-active compounds in fruity and grassy peppers (Capsicum chinense Jacq.)

Pepper (Capsicum spp.) is highly popular due to its unique flavor. However, there was limited research on the primary volatiles that influence the different flavors of fresh peppers. In this study, peppers with three aroma compound types denoted as “grassy,” “fruity,” and “no special aroma” (control) were analyzed using sensory evaluation combined with gas chromatography–mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC–O). Altogether, 393 volatiles were identified by GC–MS, and the main volatiles in peppers (C. chinense Jacq.) were esters and terpenoids. GC–O and relative odor activity value analysis revealed that 2-isobutyl-3-methoxypyrazine had a highly bitter, spicy aroma intensity in all peppers. Hexanal and trans-2-hexenal were the main aroma-active compounds in grassy peppers. In addition, citronellal was determined to be a crucial aroma-active compound in fruity peppers. This study offers a theoretical foundation for guiding the growth of the pepper processing industry and breeding.

Effect of fresh pepper at different ripening stages on the physiochemical quality and flavor of fermented Chinese pepper

Effect of fresh pepper at different ripening stages on the physiochemical quality and flavor of fermented Chinese pepper

Alterations in physico-chemical properties, microstructure, sensory characteristics, and volatile compounds of red pepper (Capsicum annuum var. conoides) during various thermal drying durations

Red pepper (Capsicum annuum var. conoides) is commonly used for dried pepper production in China, and the drying process, particularly the during duration, profoundly affects its quality. The findings indicate that prolonged exposure to high temperatures during thermal drying results in significant darkening, an evident decrease in red and yellow tones, and gradual transformation of the pepper's microscopic structure from granular to compact, along with 88% reduction in moisture content and 81% decrease in thickness. The capsaicinoid content increased, resulting in a 4.3-fold increase in spiciness after drying compared to that of fresh pepper. The pepper aroma shifts from fruity, choking, and grassy to herb, dry wood, and smoky. Compounds such as 2-Acetylfuran, furfural, 2-methylfuran, 1-methylpyrrole, 2-methylpyrazine, and 2,5-dimethylpyrazine exhibited positive correlations with drying time, whereas ethyl 2-methylpropanoate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl hexanoate, and 3-methylbutyl butanoate showed negative correlations, indicating their potential as markers for monitoring thermal drying processes.

Influence of the Drying Process on the Volatile Profile of Different Capsicum Species.

Chili is a globally significant spice used fresh or dried for culinary, condiment, and medicinal purposes. Growing concerns about food safety have increased the demand for high-quality products and non-invasive tools for quality control like origin tracing and safety assurance. Volatile analysis offers a rapid, comprehensive, and safe method for characterizing various food products. Thus, this study aims to assess the impact of the drying process on the aromatic composition of various Capsicum species and to identify key compounds driving the aromatic complexity of each genetic makeup. To accomplish these objectives, the aroma was examined in fruits collected from 19 different pepper accessions (Capsicum sp.) belonging to four species: one ancestral (C. chacoense) and three domesticated pepper species (C. annuum, C. baccatum and C. chinense). Fresh and dried samples were analyzed using a headspace PTR-TOF-MS platform. Our findings reveal significant changes in the composition and concentration of volatile organic compounds (VOCs) from fresh to dried Capsicum. Notably, chili peppers of the species C. chinense consistently exhibited higher emission intensity and a more complex aroma compared to other species (both fresh and dried). Overall, the data clearly demonstrate that the drying process generally leads to a reduction in the intensity and complexity of the aromatic compounds emitted. Specifically, fresh peppers showed higher volatile organic compounds content compared to dried ones, except for the two sweet peppers studied, which exhibited the opposite behavior. Our analysis underscores the variability in the effect of drying on volatile compound composition among different pepper species and even among different cultivars, highlighting key compounds that could facilitate species classification in dried powder. This research serves as a preliminary guide for promoting the utilization of various pepper species and cultivars as powder, enhancing product valorization.

Lactic Acid Bacteria Isolation from Üçburun Peppers and Comparison of the Different Production Process for Pickled Pepper

In recent years, the number of conscious consumers who care about accessing safe food has increased, and this has brought about an increased interest in pickle products that do not contain preservatives and are obtained by natural fermentation. With the negative effects of food additives on health coming to the forefront, the search for new and natural methodologies in pickle production processes has begun. For this purpose, lactic acid bacteria (LAB), which is the most common bacteria in pickle fermentation and a normal microbiota member of fresh peppers, is used for natural fermentation studies in pickle production. In this context, this study aimed to sample Üçburun pepper (Capsicum annuum var. annuum L., “Golden Greek”) for LAB isolation and to compare two different pickle production techniques within the scope of industrial processing. Accordingly, sampling was performed from two different sampling points for LAB isolation. The phenotypic and biochemical characteristics of the obtained isolates were determined. Kit-based identification of 10 isolates that were determined to exhibit different profiles was carried out using the API 50CH kit. To obtain additive-free pickled peppers on an industrial scale, two different pickle production processes (fermentation and acidification methods) were applied. According to the analysis results and the differences in the production stages of stock pickles, it has been seen that the pickles obtained by the acidification method are more suitable for pickle industry production.

Evaluation of antioxidant capacity and bioactive compounds in Capsicum annum L. red peppers following drying in a polycarbonate greenhouse

Abstract The current study aims to provide insights into the drying of agro products, with a specific focus on Capsicum annum L. (red pepper). Among open sun drying (OSD), polyethylene bag drying (PBD), and polycarbonate sheet drying (PCSD), PCSD was efficient requiring around 24 hours with a maximum yield of 350 g of dried product per 1000 g of supplied fresh peppers. The PCSD dried chili also showed greater retention of antioxidant markers (capsaicin and dihydrocapsaicin) than OSD and PBD as evidenced by UV-VIS spectroscopy. Additionally, the PCSD dried chili demonstrated highest antioxidant potential via ABTS (2, 2′-Azinobis-3-Ethylbenzothiazoline-6-Sulfonic Acid). Interestingly, the presence of various aromatic compounds and other chemical groups, indicated the occurrence of capsaicin and dihydrocapsaicin in each drying method used. The study suggests that PCSD sheet drying is an efficient and cost-effective approach that can conserve the antioxidant potential of agro products such as red pepper.

Response of Microbial Recovery Rate to Straw Return after Calcium Cyanamide Soil Disinfection

At present, returning vegetable straw in situ is an effective measure to solve environmental pollution and improve soil properties. However, the direct return of straw to the field can reduce the release rate of soil organic matter and cause serious soilborne diseases. The combined application of calcium cyanamide (CaCN2) and straw can solve this problem. The objective of this study was to determine the effect of CaCN2 combined with pepper straw return on cucumber yield, soil physicochemical properties, and soil microbial communities during 2020 to 2021 in Shandong Province, China. The treatments were designed as follows: (1) calcium cyanamide soil disinfection, CC; (2) fresh pepper straw return, LJ; (3) fresh pepper straw return combined with calcium cyanamide disinfection, LJ+CC; and (4) natural soil without straw return treatment, CK. Compared with CK, the LJ+CC treatment significantly improved cucumber production by 20%. The cultivable microbial community in the soil was temporarily inhibited during soil fumigation treatment, and the cultivable bacterial and actinomycete communities in the soil return to their initial levels after the film was removed (harvest period). The numbers of culturable bacteria and actinomycetes in the soil in the LJ+CC treatment were 4.68 × 107 CFU/g and 5.17 × 107 CFU/g, respectively, higher than those in the soil in the CC treatment. The contents of TN and OM in the LJ+CC treatment increased by 13.1% and 13.5%, respectively, compared with that in LJ. Therefore, the LJ+CC treatment enhanced soil fertility and cucumber yields. CaCN2 can promote straw decomposition and straw can promote soil microbial recovery, and their combined application is considered a feasible and sustainable technique for utilizing vegetable residues in the greenhouse. The combination of returning pepper straw to the field and calcium cyanamide technology achieves a win-win situation of resource circulation and economic circulation by converting agricultural waste into fertilizer before being put into production. Based on this, it is recommended that the straw returning technology receives strong policy support, stimulates researchers to explore the feasibility of different vegetable straw returning to the field, promotes the implementation of this technology achievement, and leverages the environmental benefits of the application of straw returning technology.

Influence of wood type on anthraquinone levels and quality properties of smoked chipotle pepper

This study aimed to assess the effects of pecan and mesquite wood, as well as smoking time, on anthraquinone (AQ) levels and quality properties of chipotle pepper (CHP) during the traditional smoking process. Changes in moisture content, microstructure, levels of total phenols (TPs), AQ, capsaicin (CAPS), dihydrocapsaicin (DHC), total polyphenols (TPPs), and total antioxidant activity (TAA), as well as color parameters, were measured. A wood mixture consisting of pecan, poplar, mesquite, and pine was used as the control. The CHP moisture content consistently decreased from 12 to 108 h of smoking, with long times exhibiting asymptotic trends across all treatments. Concurrently, structural changes, such as pericarp thinning and plant tissue collapse, were observed as the smoking process progressed. The wood type and processing time had a significant impact (P < 0.05) on TPs, AQ, CAPS, DHC, TAA levels, and color. TPs and AQ exhibited behavior opposite to that of the moisture content. CHP smoked in mesquite wood exhibited the highest TPs absorption rate and the lowest AQ levels. However, the AQ levels in CHP using any wood type exceeded permissible limits (0.02 mg·kg−1) at 12 h of processing, with the control exhibiting the highest AQ concentrations. The highest concentrations of CAPS and DHC were observed at 36 h in all treatments, with lower losses in mesquite wood CHP. The control exhibited the highest TAA values compared to fresh peppers. CHP color (a*, redness) decreased throughout the smoking process. The pecan and mesquite wood treatments resulted in the lowest loss of a* (P < 0.05). These results indicate that using mesquite wood for CHP production promotes higher TPs concentrations with lower AQ levels, followed by pecan wood, when compared to the control. These findings suggest the need to investigate the mechanisms of AQ formation to achieve CHP parameters within the regulatory limits with good quality.

Residue behavior and processing factors of thirteen field-applied pesticides during the production of Chinese traditional fermented chopped pepper and chili powder.

In this study, the fate, processing factors and relationship with physicochemical properties of thirteen pesticides in field-collected pepper samples during Chinese chopped pepper and chili powder production was systematically studied. The washing, air-drying, chopping and salting and fermentation processes reduced 24.8%-62.8%, 0.9%-26.4%, 25.1%-50.3% and 16.3%-90.0% of thirteen pesticide residues, respectively, while the sun-drying processing increased the residues of eleven pesticides by 1.27-5.19 fold. The PFs of thirteen pesticides were<1 in chopped pepper production and the PFs of eleven pesticides were more than 1 for chili powder production. The chopped pepper processing efficiency have most negative correlation with octanol-water partition coefficient. In contrast, the chili powder processing efficiency have most positive correlation with vapour pressure. Thus, this study can offer important references for assessment the pesticide residue levels in Chinese traditional fermented chopped pepper and chili powder production from fresh peppers.

Cinnamaldehyde Inhibits Postharvest Gray Mold on Pepper Fruits via Inhibiting Fungal Growth and Triggering Fruit Defense.

Gray mold infected with Botrytis cinerea frequently appears on fruits and vegetables throughout the supply chain after harvest, leading to economic losses. Biological control of postharvest disease with phytochemicals is a promising approach. CA (cinnamaldehyde) is a natural phytochemical with medicinal and antimicrobial activity. This study evaluated the effect of CA in controlling B. cinerea on fresh pepper fruit. CA inhibited B. cinerea growth in vitro significantly in a dose- (0.1-0.8 mM) and time-dependent (6-48 h) manner, with an EC50 (median effective concentration) of 0.5 mM. CA induced the collapse and breakdown of the mycelia. CA induced lipid peroxidation resulting from ROS (reactive oxygen species) accumulation in mycelia, further leading to cell leakage, evidenced by increased conductivity in mycelia. CA induced mycelial glycerol accumulation, resulting in osmotic stress possibly. CA inhibited sporulation and spore germination resulting from ROS accumulation and cell death observed in spores. Spraying CA at 0.5 mM induced a defense response in fresh pepper fruits, such as the accumulation of defense metabolites (flavonoid and total phenols) and an increase in the activity of defense enzymes (PAL, phenylalanine ammonia lyase; PPO, polyphenol oxidase; POD, peroxidase). As CA is a type of environmentally friendly compound, this study provides significant data on the activity of CA in the biocontrol of postharvest gray mold in peppers.

Fate of Amadori compounds in processing and digestion of multi-ingredients tomato based sauces and their effect on other microconstituents

Amadori compounds (ACs), the first stable products of Maillard reaction, are detected in various products of fruits and vegetables, and show an antioxidant activity which can be related to beneficial effects in human health. In order to optimize the nutritional quality of a multi-ingredient tomato sauce (tomato puree – onion – olive oil – dried pepper), the fate of ACs during processing (drying, heating) and gastrointestinal digestion of a model meal was assessed as well as that of other microconstituents, i.e. carotenoids, phenolic compounds and capsaicinoids. The drying at 50 °C of fresh pepper induced the formation and accumulation of ACs after 6 days. During the heat treatment by microwave of multi-ingredient tomato sauce, Maillard reaction occurs in presence of dried pepper and the content in ACs in the tomato-based sauces increased (+33% to + 53%) depending of quantities of dried pepper added. The bioaccessibility of total ACs was 24–31% in duodenal phase and 18–22% in jejunal phase. Individual ACs have shown variable bioaccessibility, e.g. very high for Fru-Arg (50.8% to 71.3%), and very low for Fru-Met (1.8% to 2.2%). The kinetic monitoring of ACs in digestion medium showed that ACs are not stable (-46% in gastric phase, −49 % in intestinal phase) which indicated their potential degradation in the digestive tract. The presence of ACs in the multi-ingredients tomato sauces had no effect on the content of the other bioactive compounds monitored in the study and even promoted the bioaccessibility of total lycopene (+30%) but decreased the bioaccessibility of total phenolic compounds.

A Comprehensive Review of Pesticide Residues in Peppers

Pesticides are chemicals that are used to control pests such as insects, fungi, and weeds. Pesticide residues can remain on crops after application. Peppers are popular and versatile foods that are valued for their flavor, nutrition, and medicinal properties. The consumption of raw or fresh peppers (bell and chili) can have important health benefits due to their high levels of vitamins, minerals, and antioxidants. Therefore, it is crucial to consider factors such as pesticide use and preparation methods to fully realize these benefits. Ensuring that the levels of pesticide residues in peppers are not harmful to human health requires rigorous and continuous monitoring. Several analytical methods, such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), and nuclear magnetic resonance spectroscopy (NMR), can detect and quantify pesticide residues in peppers. The choice of analytical method depends on the specific pesticide, that is being tested for and the type of sample being analyzed. The sample preparation method usually involves several processes. This includes extraction, which is used to separate the pesticides from the pepper matrix, and cleanup, which removes any interfering substances that could affect the accuracy of the analysis. Regulatory agencies or food safety organizations typically monitor pesticide residues in peppers by stipulating maximum residue limits (MRLs). Herein, we discuss various sample preparation, cleanup, and analytical techniques, as well as the dissipation patterns and application of monitoring strategies for analyzing pesticides in peppers to help safeguard against potential human health risks. From the authors' perspective, several challenges and limitations exist in the analytical approach to monitoring pesticide residues in peppers. These include the complexity of the matrix, the limited sensitivity of some analytical methods, cost and time, a lack of standard methods, and limited sample size. Furthermore, developing new analytical methods, using machine learning and artificial intelligence, promoting sustainable and organic growing practices, improving sample preparation methods, and increasing standardization could assist efficiently in analyzing pesticide residues in peppers.

Evaluation of Total Polyphenol and Flavonoid Contents of Fresh and Dried Pepper (&amp;lt;i&amp;gt;Piper nigrum&amp;lt;/i&amp;gt;) from the Ivory Coast

The growing interest in the potential biological activity of polyphenols and flavonoids has highlighted necessity to assess their content in fresh and dried pepper from Ivory Coast. The total polyphenol content was determined using the Folin-Ciocalteu test and the total flavonoid content was also measured spectrophotometrically using the aluminum chloride colorimetric test. The results obtained indicate the total polyphenol levels of fresh and dried peppers are higher in the samples collected in Danane (0.8 ± 0.05 mg GAE/100g) and in Azaguie (0.4 ± 0.08 mg GAE/100g). The lowest concentrations were obtained with fresh and dried pepper samples collected in N’douci (0.22 ± 0.02 mg GAE/100g) and in PK 103 (0.22 ± 0.02 mg GAE/100g). The highest content of total flavonoids was revealed in the locality of PK 103 (1.85 ± 0.62 mg EC/100g) followed by the locality of Maféré (1.37 ± 0.25 mg EC/100g) respectively for black pepper and green pepper. Then, the lowest flavonoid contents were obtained in the dried pepper of Lopou (0.57 ± 0.03 mg EC/100g) and the fresh pepper of PK 103 (0.47 ± 0.03 mg EC/100g). The results obtained highlight the importance of these black spices as promising sources of phenolic compounds and could be used in pharmaceutical treatments and in food.

Identification and validation of core microbes associated with key aroma formation in fermented pepper paste (Capsicum annuum L.)

Fermented peppers are usually obtained by the spontaneous fermentation of microorganisms attached to fresh peppers, and the variable microbial composition would lead to inconsistencies in flavor between batches. To demonstrate the roles of microorganisms in flavor formation, the core microbes closely associated with the key aroma compounds of fermented pepper paste were screened and validated in this study. Lactobacillus was the dominant bacterial genus in fermented pepper paste, whereas the main fungal genera were Alternaria and Kazachstania. Nine strains of the genera Lactobacillus, Weissella, Bacillus, Zygosaccharomyces, Kazachstania, Debaryomyces, and Pichia were isolated from fermented pepper paste. Eleven key aroma compounds were identified using gas chromatography combined with olfactometry and relative odor activity values. Correlation analysis showed that Zygosaccharomyces and Kazachstania were positively correlated with the majority of the key aroma compounds, whereas Lactobacillus was negatively correlated with them. Thus, Zygosaccharomyces and Kazachstania were identified as core genera associated with the key odorants. Finally, Zygosaccharomyces bisporus, Kazachstania humilis, and Lactiplantibacillus plantarum were used as starter cultures for fermented peppers, confirming that Z. bisporus and K. humilis were more beneficial for the key aroma compounds (e.g., acetate, linalool, and phenyl ethanol) rather than L. plantarum. This study contributed to understanding the flavor formation mechanism and provided references for the quality control of food fermentation.

Co-milling of sound olives with fresh chili peppers improves the volatile compound, capsaicinoid and sensory profiles of flavoured olive oil with respect to the typical infusion

In the context of the olive oil flavoured with chili peppers, the aim of this study was to compare co-milling of sound olives and fresh chili peppers at mill scale to infusion of dried chili peppers in oil, using the same batch of olives for all oils. Capsaicinoids by HPLC-DAD, volatile profile by HS-SPME-GC-MS and HS-GC-IMS and sensory profile were characterized. Capsaicinoids were statistically higher in oils prepared with green (52.0–68.0 mg/kg) than red (48.0–60.2 mg/kg) chili peppers. Oils flavoured by infusion showed higher contents of volatile compounds linked to defects such as acetic acid, with winey/vinegary sensory defect (median, 1.72–2.02) and no fresh pepper flavour. Oils prepared by co-milling resulted rich in the typical esters of chili pepper (6.175 and 4.156 mg/kg with green and red chili peppers, respectively), with pleasant hotness sensation and fresh pepper flavour. Overall, the co-milling approach allowed obtaining flavoured samples with improved sensory quality.

The Changes in Bell Pepper Flesh as a Result of Lacto-Fermentation Evaluated Using Image Features and Machine Learning.

Food processing allows for maintaining the quality of perishable products and extending their shelf life. Nondestructive procedures combining image analysis and machine learning can be used to control the quality of processed foods. This study was aimed at developing an innovative approach to distinguishing fresh and lacto-fermented red bell pepper samples involving selected image textures and machine learning algorithms. Before processing, the pieces of fresh pepper and samples subjected to spontaneous lacto-fermentation were imaged using a digital camera. The texture parameters were extracted from images converted to different color channels L, a, b, R, G, B, X, Y, and Z. The textures after selection were used to build models for the classification of fresh and lacto-fermented samples using algorithms from the groups of Lazy, Functions, Trees, Bayes, Meta, and Rules. The highest average accuracy of classification reached 99% for the models developed based on sets of selected textures for color space Lab using the IBk (instance-based K-nearest learner) algorithm from the group of Lazy, color space RGB using SMO (sequential minimal optimization) from Functions, and color space XYZ and color channel X using IBk (Lazy) and SMO (Functions). The results confirmed the differences in image features of fresh and lacto-fermented red bell pepper and revealed the effectiveness of models built based on textures using machine learning algorithms for the evaluation of the changes in the pepper flesh structure caused by processing.

Effect of Fruit Weight and Fruit Locule Number in Bell Pepper on Industrial Waste and Quality of Roasted Pepper

Bell pepper (Capsicum annuum L.), one of the most consumed vegetables worldwide, shows great differences between its diverse varieties. These differences affect the fruit type, size and shape. Food preservation techniques prolong the availability of sweet pepper. Roasted pepper is a product marketed with the European recognition of Protected Geographical Indication ‘Pimiento Asado del Bierzo’. The objective of this work was to analyse the effect of the fruit weight and fruit locule number of the industrial fresh pepper on quality and roasted pepper yield. Large trilocular fruits and large tetralocular fruits reached higher roast yield and uniformity than small trilocular fruits. Regardless of fruit locule number and fruit weight, the overall quality of all the samples of roasted pepper was categorised as very good. Large tetralocular and large trilocular fruits are the most appropriate peppers for industrial purposes, whereas small trilocular fruits should be intended for the fresh product market. This easy method of sorting bell pepper fruit attending to fruit weight will decrease the amount of pepper waste in the industrial roasting process (around 18%), while maintaining the high overall quality of the final product. Moreover, the faster peeling of large peppers will also contribute to increasing the productivity of the industrial processing of roasted pepper.

Effects of use of modified traditional driers in making smoked paprika “Pimentón de La Vera”, on pepper quality and mitigation of PAH contamination

“Pimentón de La Vera” is a smoked paprika regulated by a Protected Designation of Origin. The smoking process confers highly-valued sensorial properties to paprika. However, this particular drying process also increases the levels of polycyclic aromatic hydrocarbons to concerning concentrations. In this work, two modified dryers were compared to a traditional dryer as a strategy to mitigate PAH contamination. Drying parameters (temperature and humidity of the dryers, days of drying required), quality of the peppers (moisture, reflected colour parameters, ASTA (American Spice Trade Association) units, PACI ([1000a*/(L* + H*)]) index, and colour stability), and the content of benzo(a)pyrene, chrysene, benzo(b)fluoranthene, and benzo(a)anthracene were evaluated during four different seasons. The moisture of the fresh peppers varied among the seasons (ranging from 69.4% to 81.4%), and was positively related with lower drying times. There were no differences in the final moisture of the peppers on the basis of dryer type used. Different seasons influenced the colour values of the dried peppers. Peppers obtained from dryer type 2 presented the highest values of extractable colour (133 ASTA units). Differences in PAH4 levels were observed between seasons (ranging from 277 to 1208 µg/kg) and between the types of dryer used (ranging from 432 to 932 µg/kg). Dryer type 2, characterized by combustion of firewood in a closed chamber and forced convection with a fan, diminished the levels of PAHs contamination and maintained the quality of the smoked paprika.

Pulsed Vacuum Drying of Pepper (Capsicum annuum L.): Effect of High-Humidity Hot Air Impingement Blanching Pretreatment on Drying Kinetics and Quality Attributes.

With a high moisture content, fresh peppers are perishable and rot easily. Drying is essential for shelf-life extension. The natural thin wax layer on the pepper surface hinders moisture transfer. Traditionally, chemical dipping or mechanical pricking is used to remove this wax layer. However, in chemical dipping, chemical residues can trigger food-safety issues, while the low efficiency of mechanical pricking hinders its industrial application. Feasible pretreatment methods are advantageous for industrial use. Here, an emerging pretreatment technique (high-humidity hot-air impingement blanching, HHAIB) was used for peppers before drying and its effects on drying characteristics, microstructure, and polyphenol oxidase (PPO) activity were explored. The impact of drying temperature on color parameters and red pigment content of pulsed-vacuum-dried peppers was also evaluated. PPO activity was reduced to less than 20% after blanching at 110 °C for 60 s. HHAIB reduced drying time and PPO activity and promoted chemical-substance release. Effective water diffusivity was highest (5.01 × 10−10 m2/s) after blanching at 110 °C for 90 s, and the brightness value and red pigment content were highest (9.94 g/kg) at 70 °C. HHAIB and pulsed vacuum drying are promising pretreatment and drying methods for enhancing the drying rate and quality of red peppers.

Non-destructive prediction of the hotness of fresh pepper with a single scan using portable near infrared spectroscopy and a variable selection strategy.

There has been no study on using near-infrared spectroscopy (NIRS) to predict the hotness of fresh pepper. This study is aimed at developing a non-destructive and accurate method for determining the hotness of fresh peppers using portable NIRS and the variable selection strategy. Spectra from different locations on samples were obtained non-destructively with a single scan. Quantitative models were established using partial least squares (PLS) with a variable selection method or fusion method. The results showed that near-stalk was the best spectral acquisition location for quantitative analysis. The variable selection strategy allows the selection of targeted characteristic variables and improves the results. A fusion method, namely variable adaptive boosting partial least squares (VABPLS), was selected for optimal prediction of the performance. In the optimized model, the root mean square errors of prediction for the validation set (RMSEPvs) of capsaicin, dihydrocapsaicin and pungency degree were 0.295, 0.143 and 47.770, respectively, while the root mean square errors of prediction for the prediction set (RMSEPps) collected one month later were 0.273, 0.346 and 75.524, respectively.