Influence of drying techniques and growing location on the chemical composition of sweet pepper (Capsicum annuum L., var. Senise)

Assessment of the Effects of Roasting, Contact Grilling, Microwave Processing, and Steaming on the Functional Characteristics of Bell Pepper (Capsicum annuum L.)

Bell peppers (Capsicum annuum L.) in various stages of maturity are widely used in the diets of individuals and in the food industry; they are consumed both fresh and after thermal processing. However, every type of processing impacts the overall textural and bioactive characteristics of this plant-based food. In order to quantify the changes in the bioactive substances and color-structural characteristics that occur during selected heat treatments (contact grilling, roasting, roasting combined with microwaving, and steam cooking) of bell peppers at three maturity stages (green, yellow, and red), analyses of antioxidant activity, reducing sugar content, polyphenolic compound content, textural properties, and color coordinates in the L*a*b* system were carried out. Some of the processes used, such as contact grilling (15.43 mg GAE/g d.b.) and roasting combined with microwaving (15.24 mg GAE/g d.b.), proved to be beneficial as the total polyphenol content of green peppers (2.75 mg GAE/g d.b.) increased. The roasting (3.49 mg TE/g d.b.) and steaming (6.45 mg TE/g d.b.) methods decreased the antioxidant activity of yellow bell peppers (14.29 mg TE/g d.b.). Meanwhile, the roasting (0.88 mg Glc/g d.b.), contact-grilling (2.19 mg Glc/g d.b.), simultaneous microwaving and roasting (0.66 mg Glc/g d.b.), and steaming (1.30 mg Glc/g d.b.) methods significantly reduced the content of reducing sugars and reducing substances in red bell peppers (4.41 mg Glc/g d.b.). The studies proved that in order to preserve the antioxidant and bioactive properties of bell peppers, it is necessary to consider the use of appropriately selected heat treatments, depending on the different stages of maturity. The proper selection of adequate thermal treatment can not only increase digestibility, but also improve the bioavailability of bioactive substances from this raw material.

Antioxidant potential and factors influencing the content of antioxidant compounds of pepper: A review with current knowledge

The use of natural food items as antioxidants has gained increasing popularity and attention in recent times supported by scientific studies validating the antioxidant properties of natural food items. Peppers (Capsicum spp.) are also important sources of antioxidants and several studies published during the last few decades identified and quantified various groups of phytochemicals with antioxidant capacities as well as indicated the influence of several pre- and postharvest factors on the antioxidant capacity of pepper. Therefore, this review summarizes the research findings on the antioxidant activity of pepper published to date and discusses their potential health benefits as well as the factors influencing the antioxidant activity in pepper. The major antioxidant compounds in pepper include capsaicinoids, capsinoids, vitamins, carotenoids, phenols, and flavonoids, and these antioxidants potentially modulate oxidative stress related to aging and diseases by targeting reactive oxygen and nitrogen species, lipid peroxidation products, as well as genes for transcription factors that regulate antioxidant response elements genes. The review also provides a systematic understanding of the factors that maintain or improve the antioxidant capacity of peppers and the application of these strategies offers options to pepper growers and spices industries for maximizing the antioxidant activity of peppers and their health benefits to consumers. In addition, the efficacy of pepper antioxidants, safety aspects, and formulations of novel products with pepper antioxidants have also been covered with future perspectives on potential innovative uses of pepper antioxidants in the future.

The Effect of the Varietal Type, Ripening Stage, and Growing Conditions on the Content and Profile of Sugars and Capsaicinoids in Capsicum Peppers

Peppers (Capsicum sp.) are used both as vegetables and/or spice and their fruits are used in a plethora of recipes, contributing to their flavor and aroma. Among flavor-related traits, pungency (capsaicinoids) and lately volatiles have been considered the most important factors. However, the knowledge of sugars is low, probably due to the fact peppers were historically considered tasteless. Here, using HPLC, we studied the content and profile of major sugars and capsaicinoids in a comprehensive collection of varietal types (genotype, G), grown under different growing systems (environment, E) in two years (Y) and considered the two main ripening stages (R). We found a major contribution to the ripening stage and the genotype in total and individual sugars and capsaicinoids. The year was also significant in most cases, as well as the G × E and G × Y interactions, while the growing system was low or nil. Ripening increased considerably in sugars (from 19.6 to 36.1 g kg^-1 on average) and capsaicinoids (from 97 to 142 mg kg^-1 on average), with remarkable differences among varieties. Moreover, sugars in fully ripe fruits ranged between 7.5 and 38.5 g kg^-1 in glucose and between 5.2 and 34.3 g kg^-1 in fructose, and several accessions reached total sugars between 40 and 70 g kg^-1, similar to tomatoes. The results reveal the importance of the genotype and the ripening for these traits, particularly sugars, which should be considered key for the improvement of taste and flavor in peppers.

Geographical Discrimination of Bell Pepper (Capsicum annuum) Spices by (HS)-SPME/GC-MS Aroma Profiling and Chemometrics

Dried and ground red pepper is a spice used as seasoning in various traditional dishes all over the world; nevertheless, the pedoclimatic conditions of the diverse cultivation areas provide different chemical characteristics, and, consequently, diverse organoleptic properties to this product. In the present study, the volatile profiles of 96 samples of two different ground bell peppers harvested in diverse Italian geographical areas, Altino (Abruzzo) and Senise (Lucania), and a commercial sweet paprika, have been studied by means of headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The investigation of their volatile profile has led to the identification of 59 analytes. Eventually, a discriminant classifier, Partial Least Squares Discriminant Analysis (PLS-DA), was exploited to discriminate samples according to their geographical origin. The model provided very accurate results in external validation; in fact, it correctly classified all the 30 test samples, achieving 100% correct classification (on the validation set). Furthermore, in order to understand which volatiles contribute the most at differentiating the bell peppers from the different origins, a variable selection approach, Variable Importance in Projection (VIP), was used. This strategy led to the selection of sixteen diverse compounds which characterize the different bell pepper spices.

Experimental races of Capsicum annuum cv. jalapeño: Chemical characterization and classification by 1H NMR/machine learning

This work reports on the metabolic fingerprinting of ten new races of Capsicum annuum cv. jalapeño using ¹H NMR based metabolomics coupled to machine learning projections. Ten races were classified and evaluated according to their differential metabolites, variables of commercial interest and by multivariate data analysis/machine learning algorithm. According to our results, experimental races of jalapeño peppers exhibited differences in carbohydrate, amino acid, nucleotide and organic acid contents. Forty-eight metabolites were identified by 1D and 2D NMR and the differential metabolites were quantified by qNMR. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) separated the studied races into two groups. The group A included the races Colosus, Emperador, Fundador and Rayo whereas the group B included the races Don Benito, SMJ 1416, SMJ 1417, SMJ 1423, SMJ 145 and STAM J0904. OPLS-DA revealed that levels of citric acid in group A were higher than in group B, while the levels of asparagine, fumaric acid, GABA, glucose, malic acid, pyruvic, quinic acid, sucrose and tryptophan were higher in the group B. Remarkably, ascorbic acid was exclusively found in the race Colosus. Random forest model revealed the diversity of the experimental races and the similarity rate with the well-established races. The most relevant variables used to generate a model were length, weight, yield, width, xylose content and organic acids content.

Phytochemical Profile of Capsicum annuum L. cv Senise, Incorporation into Liposomes, and Evaluation of Cellular Antioxidant Activity

Overproduction of oxidants in the human body is responsible for oxidative stress, which is associated with several diseases. High intake of vegetables and fruits can reduce the risk of chronic diseases, as they are sources of bioactive compounds capable of contrasting the free radical effects involved in cancer, obesity, diabetes, and neurodegenerative and cardiovascular diseases. Capsicum annuum L. cv Senise is a sweet pepper that is grown in the Basilicata region (Italy). It is an important source of polyphenols, carotenoids, and capsinoids and can play a key role in human health. In this study, an ethanol extract was obtained from C. annuum dried peppers and the analysis of the phytochemical composition was performed by LC-ESI/LTQ Orbitrap/MS. The extract was incorporated into liposomes, which showed small size (~80 nm), good homogeneity, negative surface charge, and good stability in storage. The biological activity of the extract was evaluated in the human hepatoma (HepG2) cell line, used as model cells. The extract showed no cytotoxic activity and reduced the intracellular reactive oxygen species (ROS) level in stressed cells. The antioxidant activity was further improved when the extract was loaded into liposomes. Moreover, the extract promoted the expression of endogenous antioxidants, such as catalase, superoxide dismutase, and glutathione peroxidase through the Nrf-2 pathway evaluated by RT-PCR.

Species Composition and Toxigenic Potential of Fusarium Isolates Causing Fruit Rot of Sweet Pepper in China

Apart from causing serious yield losses, various kinds of mycotoxins may be accumulated in plant tissues infected by Fusarium strains. Fusarium mycotoxin contamination is one of the most important concerns in the food safety field nowadays. However, limited information on the causal agents, etiology, and mycotoxin production of this disease is available on pepper in China. This research was conducted to identify the Fusarium species causing pepper fruit rot and analyze their toxigenic potential in China. Forty-two Fusarium strains obtained from diseased pepper from six provinces were identified as F. equiseti (27 strains), F. solani (10 strains), F. fujikuroi (five strains). This is the first report of F. equiseti, F. solani and F. fujikuroi associated with pepper fruit rot in China, which revealed that the population structure of Fusarium species in this study was quite different from those surveyed in other countries, such as Canada and Belgium. The mycotoxin production capabilities were assessed using a well-established liquid chromatography mass spectrometry method. Out of the thirty-six target mycotoxins, fumonisins B₁ and B₂, fusaric acid, beauvericin, moniliformin, and nivalenol were detected in pepper tissues. Furthermore, some mycotoxins were found in non-colonized parts of sweet pepper fruit, implying migration from colonized to non-colonized parts of pepper tissues, which implied the risk of mycotoxin contamination in non-infected parts of food products.