Process Adaptability Appraisal of Fermented Chopped Chili Pepper Made from Fresh Chili Peppers of Different Varieties

Abstract

Fermented chopped chili pepper (FCCP) is the most important fermented and processed chili pepper product, and most pepper varieties can be processed with obvious flavor differences. Many studies have tried to explain these differences using the results of component analysis, processing technology, the microbes involved, etc., but few have examined the characteristics of these varieties along with the flavor of products. We conducted a physiochemical characteristic analysis of 35 kinds of fresh chili peppers with different genotypes and made fermented products from 17 varieties, using principal component analysis (PCA) and cluster analysis (CA) to correlate their components with FCCP products. The results were as follows: (1) Protein, total acids, a* (representation of the object’s red and green color), protopectin, and fruit thickness are the five key indexes that affect the quality of fresh chili peppers the most. (2) Protein, total acids, a*, protopectin, and fruit thickness are also the key indexes that affect the quality of FCCP. (3) Suitable ranges of fresh chili pepper to manufacture FCCP are 1.3–2.0 g/100 g for protein, 2.5–4.0 g/kg for total acids, 10–15 g/100 g for protopectin, 30–39 for a*, and 1.2–2.0 mm for fruit thickness. (4) Sensory appraisal shows crispness is the most important mouthfeel sensation and can decrease during the process. The varieties with the top three scores were A12 (21G675), A13 (20Z663), and A14 (21Z698) with scores of 87.92, 74.08, and 74.15, respectively. The varieties in the top three scores are pod peppers. The PCA and CA showed that pod peppers were the most suitable materials for making FCCP. Our results will benefit others in selecting fresh chili peppers for making FCCP and provide data support for directing processable variety breeding.

1. Introduction

The chili pepper (Capsicum spp.) is a variety of Capsicum of the Solanaceae family. The main varieties grown and consumed globally are C. annuum L., C. frutescens L., C. baccatum L., C. chinense Jacq., and C. pubescens Ruiz and Pav. The most common edible chili peppers are C. frutescens L. and C. chinense Jacq. The chili peppers cultivated in Hunan Province are representative of typical Chinese chili peppers, and the hybrid species mainly grown in this area are sharp peppers, line peppers, and pod peppers, which occupy about 1,075,000 hectares. The line pepper and pod pepper are the two most commonly used feedstocks for fermented chopped chili pepper (FCCP), and their cultivated area proportions are 37.4% and 11.9%, respectively.

Fermented chili peppers are made using fresh chili peppers (FCPs) as the main raw materials along with additional ingredients. They are processed through chopping or fermentation and consumed whole, as a jam-like substance, or chopped. The FCCP is the most important product of fermented chili pepper and has been the subject of many studies. Wang et al. [1] researched the course of fermentation using 10 varieties of lactic acid bacteria; based on an evaluation of the acid-producing ability, antibacterial activity, nitrite accumulation, and γ-aminobutyric acid-producing activity of the strain, they recommended using Lactobacillus fermentum, a fructose-consuming Lactobacillus, as the fermented strain. Ge et al. [2] measured the agronomic traits and physicochemical indexes of five varieties of Sanwei pepper in Xintian County, evaluating its freshly consumed palatability and processing. Wang et al. [3] evaluated 20 varieties of chili in Tibet by using indexes such as fruit shape and physicochemical indicators. Ren et al. [4] measured the crude fat, crude fiber, vitamin C, and capsaicin levels of 18 line pepper varieties and found that these four indexes were the main points of difference between the species. Cui et al. [5] analyzed 24 indexes of 18 varieties of fresh chili via principal component analysis (PCA) and clustering analysis (CA) and identified three high-quality species varieties. Peng et al. [6] measured the color, aroma, and taste of 25 dried chili varieties with an electronic nose and an electronic mouth, providing a quantitative comparison of the key indexes; this showed flavor variation between the fresh chilies and the dry-processed chilies. Liu et al. [7] measured the quality of 11 local chili varieties in Guizhou Province; capsaicin showed the largest variable coefficient. The chili pepper can also be classified into three clusters using quality indexes. Cosimo Taiti et al. [8] studied the influence of the drying process on the volatile compounds of various Capsicum varieties, finding that its volatile compound composition varies between species; however, it also has its own characteristic compound, which can be used for species classification.

However, there is a lack of research evaluating chili screening systems used to produce FCCP based on the relationship between the raw materials and the resulting products. Thus, this research aimed to establish a model to assess the quality and perform evaluations of FCPs for fermentation into FCCP. To achieve this, we analyzed line peppers and pod peppers (the main raw materials in FCCP) and the resulting products. Furthermore, we performed a correlation analysis of the flavor and compound compositions to identify the key indexes that lead to quality differences. We also did so to establish an appraisal method for FCCP process adaptability, using sensory evaluation to verify its effectiveness. Our results will lead to an appraisal model and afford important basic background information for processable species breeding.

2. Materials and Methods

2.1. Experimental Materials

Thirty-five chili varieties were picked from the Changsha Test Station of the Hunan Agriculture Research System in Changsha, Hunan, China, with a latitude of 28.5° N and a longitude of 113.3° E. The plant base of Honghe Hopen Food Co., LTD. of Jianshui County in Honghe Prefecture, Yunnan, China, has a latitude of 23.9° N and a longitude of 102.85° E (varieties’ details in Table S1). The chilies were planted on 25 April and picked on 23 July 2021. The average temperature was 29.5 °C and the average precipitation was 678 mm. Each sample was in the red ripe stage and weighed about 3 kg. The fruit samples were similar in size, about 7–9 cm in length and 1–1.5 cm in diameter. The samples were transported immediately by an air-conditioned vehicle, spread to cool in a 25 °C room with good ventilation for 24 h. The samples to measure were numbered, photographed, and kept at −40 °C for later use; the samples to process were processed immediately after the cooldown.

2.2. Processing of FCCP

Seventeen varieties of FCP were selected for fermentation using traditional FCCP technology without spicy ingredients to compare differences in the fermented products. The main processing flow is shown in Figure 1.

Procedure 1—Picking and cleaning: Fresh pepper samples were uncapped and washed for 10 min, and then water was filtered out.

Procedure 2—Drying in the air: The washed pepper samples were placed in a ventilated place to air-dry for 12 h.

Procedure 3—Chopping: The pepper samples were chopped into slices (roughly 1 cm cubes).

Procedure 4—Fermentation: First, 10% NaCl was added to the chili samples and fully blended; then, they were placed in a 5 L jar and sealed for fermentation at 25 °C for 28 days.

Procedure 5—Pasteurization: The peppers were bottled and pasteurized at 85 °C for 20 min and then cooled at room temperature (about 25 °C) for later use.

2.3. Instruments and Reagents

Analysis was carried out using an Agilent 1260 high-performance liquid chromatography (HPLC) system (Agilent Co., USA); a UV spectrophotometer (Tianjin Guanze Technology Co., Tianjin, China); an AUY200 analytical balance (SHMADZV Co., Tokyo, Japan); a K9840 Kjeldahl apparatus (Haineng Instruments Co., Shanghai, China); a TA-XT-plus food physical property tester (Stable Micro System Ltd., Godalming, UK); an ultrapure water preparation apparatus (Shenzhen Hongsen Environmental Technology Ltd., Shenzhen, China); a KQ-5200DE supersonic cleaner (Kunshan Supersonic Cleaner Ltd., Shanghai, China); and an electronic balance (Shanghai Precise Scientific Instruments Ltd., Shanghai, China).

The chemicals used included tetrahydrofuran, methanol, copper sulfate, sodium hydroxide, methylene blue, 95% ethanol, glucose, and potassium ferrocyanide—all purchased from Sino Pharming, Beijing, China, all at analytical purity (≥95%). Dihydrocapsaicin (standard), capsaicin (standard), malic acid, citric acid, and lactic acid were purchased from Aladdin, China, at chromatographical purity (≥95%).

2.4. Main Methods

2.4.1. Measurement Methods for Physicochemical Indexes

Fruit Hardness and Thickness

Twenty fruit samples from each variety were selected and their hardness and thickness were measured using a food physical property tester and vernier caliper, respectively, and the average results were reported.

Fruit Color

Ten representative fruits from each variety were selected, cleaned, and air-dried. The upper, middle, and lower parts of the chilies were randomly selected, peeled, sliced, and placed under a calibrated colorimeter (3nh, Shenzhen, China). L* (lightness), a* (green-red), and b* (yellow-blue) values were measured, and the average results were reported [9].

Texture

The chili slices with similar sizes and thicknesses were selected and placed in 4 columns: 2 columns were frontside up and 2 columns were backside up. The F_max values were measured using a P/100 probe and repeated 10 times for each sample, and the average results were reported [9].

The test conditions were as follows: 2 mm/s before the test; test speed of 1 mm/s; 10 mm/s after the test; compress ratio of 80%; pressure of 5 g.

Moisture

The moisture was measured using the direct drying method derived from the first method listed in GB5009.3-2016 of the Chinese Standardization Administration [10].

A clean aluminum weighing bottle was placed in a drying oven at 101~105 °C, and drying was repeated until the mass difference exceeded no more than 2 mg (m3). Five to ten grams of pepper (accurate to 0.0001 g) was precisely weighed in the weighing bottle (m1) and placed in a drying oven at 101~105 °C for 2–4 h and then cooled down for 0.5 h before weighing. This procedure was repeated until the mass difference exceeded no more than 2 mg (m2), calculated per the formula below:

X = (m1 − m2)/(m1 − m3) × 100

X—the moisture content (g/100 g); m1—the mass of the weighing bottle and sample (g); m2—the mass of the weighing bottle and dried sample (g); m3—the mass of the weighing bottle (g).

Protein

The protein of each sample was measured using the Kjeldahl method, as per the first method listed in GB5009.5-2016 of the Chinese Standardization Administration [11]. Ten chili fruits were randomly selected, cleaned, and air-dried from each variety. Samples were smashed and homogenized. A 3 g (accurate to 0.1 g) sample was placed in a tube and mixed with 0.4 g of CuSO₄, 6 g of K₂SO₄, and 20 mL of H₂SO₄, and placed in a nitrating furnace to nitrate. When the tube turned green and transparent, the tube was placed in the automatic Kjeldahl nitrogen determination instrument. When it cooled down with no smoke coming out, 50 mL of water, 25 mL of boric acid, and 80 mL of alkali were added and distilled for 5 min. Two drops of indicator were added into the receiving bottle, the liquid was titrated with 0.05 mol/L of HCl, and the HCl volume was recorded for calculations.

Total Acids

The total acids were measured using the potentiometric titration method from GB/T 12456-2008 of the Chinese Standardization Administration [12]. A total of 100 g of fruit was selected and smashed and 25 g of the homogenated sample was placed in a flask and titrated with 0.01 mol/mL of NaOH (pH = 8.2), recording the volume for calculations. Each variety was measured 3 times and the average results were reported.

Capsaicin

Capsaicin was measured using the method from GB21226-2007 of the Chinese Standardization Administration [13]. A total of 50 g of chili pepper was selected and dried at 50 °C for 2 h and 1 g sample was weighed and mixed with 25 mL of methyl-tetrahydrofuran in a flask. The flask was put under a 60 °C water bath in ultrasonic surroundings for 30 min. The steps were repeated twice and the extract was combined for later use.

Then, 0.01 g of capsaicin and 0.0001 g of dihydrocapsaicin were weighed and dissolved in CH₃OH. A 10 µL sample was filtered using a 20 µm filter membrane and injected into the Agilent HPLC instruments to measure the content.

HPLC conditions: Agilent C18 column (4.6 mm × 250 mm, 5 μm); eluent: CH₃OH (A)/water (B) = 75:25; wave number, 280 nm; column temperature, 30 °C; sample size, 10 µL.

Cellulose and Vitamin C

The cellulose was measured using the throne colorimetric method [14]. The samples were dried and ground into powder. Next, 0.2 g of the sample powder was put into a beaker and placed into a cold water (0 °C) bath, and 60 mL of 50% sulfuric acid was added to hydrolysis for 40 min. The supernatant in the amount of 10 mL was filled to 100 mL in a volumetric flask; 2 mL of supernatant was taken with 0.5 mL of 2% anthraquinone and 5 mL of concentrated sulfuric acid and shaken well; then, the absorbance was measured at 620 nm and the cellulose content of the sample was calculated according to the standard curve equation.

Standard curve drawing: 0, 0.40, 0.80, 1.20, 1.60, and 2.00 mL of cellulose standard solution was added to 10 mL colorimetric tube, and 2.00, 1.60, 1.20, 0.80, 0.40, and 0 mL of distilled water was added, respectively. After 0.5 mL of 2% anthraquinone and 5 mL of concentrated sulfuric acid were added, the absorbance was measured at 620 nm.

Vitamin C was measured using the molybdenum blue colorimetric method [15]. The 10 g sample was mixed with 40 mL of acetone, ground and centrifuged, and the supernatant was taken for later use. Ammonium molybdate reagent was prepared and kept at room temperature for later use. A total of 1 mL sample was mixed with 1 mL of 0.5 mol/L ammonium ferrous sulfate solution for 30 min. Then, 5 mL of 0.5 mol/L NaOH was added to hydrolysis for 10 min and reacted with ammonium molybdate reagent under a 40 °C water bath for 20 min. Finally, 1 mL of 2% acetic acid was added and the absorbance was measured and the results were calculated according to the standard curve.

Standard curve drawing: 0.1 g vitamin C powder was mixed with 10 mL of 0.1 mol/L HCl. The mixture was diluted with 0.1 mol/L HCl to different concentrations of standard solutions at 10, 20, 30, 40, and 50 mg/L, and the absorbance was measured and the results were calculated to draw the standard curve.

Soluble Glucose

The soluble glucose was measured using anthracene colorimetry [9]. First, 1 g of smashed chili was mixed with 2 mL of distilled water for a 30 min water bath. Then, 5 mL zinc acetate and potassium ferrocyanide were added to get the sample solution. The anthracene reagent was added to react for 10 min, the absorbance was measured at 620 nm, and the soluble glucose content was calculated.

Protopectin

A total of 100 g of chili was randomly selected and smashed [16]. A 5 g sample was mixed with 25 mL of absolute ethyl to extract under a 40 °C water bath, and 25 mL of 0.5 mol/L H₂SO₄ was added to hydrolyze for 1 h. Then, 0.15% carbazole ethyl solution was added to react for 30 min, the absorbance was measured at 530 nm, and the results were calculated.

Sensory Appraisal Method of FCCP

The sensory test was performed at the Food Science and Technology’s food processing sensory room at Hunan Agricultural University using the methods described by Newlove A. Afoakwah et al. [17]. Before the sensorial studies, the FCCPs were held at 28 ± 2 °C for 24 h. Each expert panel was offered 45 g of the FCCPs placed in a 40 mL transparent plastic plate branded with random 3-digit numbers. The panel members received water and unsalted crackers as palate cleaners. The sensory evaluation team comprised 20 untrained students (13 men and 7 women) who were familiar with FCCPs and could eat them without experiencing an allergic response, with each panelist completing an informed consent before the sensory test [18]. The sensory appraisal—based on taste, color, aroma, form, and crispness as per Table S2—was carried out in a room with cool, well-lit light, odor-free surroundings. Each index was assigned 20 points, 100 points in total

2.4.2. Data Analysis

All experiments were conducted in triplicate and the data were subjected to one-way ANOVA, with significance set at a 95% confidence level. Pictures were drawn with Origin Pro 2022. Descriptive analysis, correlation analysis, principal component analysis (PCA), and cluster analysis (CA) were conducted with SPSS Statistics 26 (IBM, New York, NY, USA).

3. Results and Discussion

3.1. Quality Analysis of FCP with Different Genotypes

Table 1. Basic physicochemical data of fresh chili pepper.

Geno Type	Code	Total Acids g/kg	Protopectin g/100 g	L	a*	b*	Peel Thickness mm	Hardness N/cm2
Line Pepper	21G233	2.86 ± 0.07 hij	12.54 ± 0.09 gh	31.04 ± 0.64	30.77 ± 0.77	16.97 ± 0.70	1.91 ± 0.46 defghij	3.23 ± 0.38 efghi
	21G27	2.67 ± 0.00 lm	11.06 ± 0.18 klmn	32.81 ± 0.6	33.79 ± 1.68	20.59 ± 0.90	1.61 ± 0.18 ghijklm	3.25 ± 0.52 efghi
	21G47	1.92 ± 0.08 q	10.98 ± 0.27 lmno	30.23 ± 1.79	26.49 ± 2.04	14.04 ± 0.87	2.84 ± 0.27 b	2.6 ± 0.36 ij
	Bola Redbull	2.63 ± 0.03 im	13.68 ± 0.16 e	33.4 ± 1.22	34.21 ± 1.07	19.00 ± 1.65	1.76 ± 0.3 efghijk	3.36 ± 0.72 efgh
	21G07	2.19 ± 0.11 p	11.15 ± 0.19 klm	33.38 ± 1.24	32.45 ± 2.34	19.79 ± 0.59	1.91 ± 0.42 defghij	3.02 ± 0.5 ghi
	21G228	2.93 ± 0.01 hi	11.45 ± 0.13 u	29.80 ± 1.62	28.19 ± 3.88	16.21 ± 2.47	2.22 ± 0.54 cde	3.17 ± 0.26 efghi
	21G77	1.98 ± 0.13 q	10.68 ± 0.23 no	33.26 ± 1.01	32.75 ± 0.67	19.75 ± 1.03	2.21 ± 0.44 cde	3.36 ± 0.36 efgh
	21G76	1.81 ± 0.07 q	13.14 ± 0.37 f	31.32 ± 1.35	32.51 ± 1.96	19.13 ± 1.12	2.19 ± 0.37 cdef	3.31 ± 0.53 efgh
	21G10	2.83 ± 0.01 ijk	11.45 ± 0.17 jkl	33.48 ± 1.62	31.52 ± 1.65	20.31 ± 1.88	2.14 ± 0.29 defg	3.25 ± 0.6 efghi
	21G04	2.39 ± 0.01 no	10.63 ± 0.37 no	29.64 ± 1.1	30.48 ± 1.63	18.09 ± 1.62	2.13 ± 0.59 defg	3.53 ± 0.3 defg
	21G229	2.25 ± 0.14 op	8.7 ± 0.09 s	29.31 ± 2.15	27.69 ± 3.36	16.61 ± 2.36	1.62 ± 0.35 ghijklm	3.03 ± 0.6 fghi
	21G73	2.68 ± 0.04 jklm	8.92 ± 0.11 rs	31.54 ± 1.98	30.77 ± 1.77	18.39 ± 2.49	1.44 ± 0.14 hijklmn	3.37 ± 0.64 efgh
	21G03	2.55 ± 0.13 mn	13.4 ± 0.13 ef	32.27 ± 1.47	30.82 ± 1.3	17.96 ± 0.73	1.99 ± 0.3 defg	3.7 ± 0.54 cdefg
	21G43	3.74 ± 0.03 e	17.93 ± 0.12 a	26.55 ± 2.52	21.53 ± 4.29	11.15 ± 2.34	1.97 ± 0.24 defgh	2.79 ± 0.19 hij
	21G90	1.88 ± 0.04 q	12.14 ± 0.15 hi	33.75 ± 2.16	31.99 ± 1.27	21.99 ± 2.92	1.65 ± 0.1 fghijkl	3.36 ± 0.20 efgh
	21G25	2.68 ± 0.14 jklm	7.67 ± 0.08 t	32.76 ± 1.25	30.29 ± 3.92	18.42 ± 1.25	1.9 ± 0.43 defghij	3.35 ± 0.43 efgh
Pod pepper	21Z604	4.83 ± 0.13 a	13.73 ± 0.06 de	33.47 ± 1.3	36.97 ± 1.21	21.72 ± 1.35	1.42 ± 0.2 ijklmn	3.52 ± 0.62 defg
	20Z663	3.75 ± 0.04 e	17.06 ± 0.09 b	33.09 ± 1.97	32.82 ± 1.89	19.59 ± 1.52	1.37 ± 0.07 jklmn	3.45 ± 0.56 defgh
	20Z702	3.97 ± 0.02 cd	13.48 ± 0.19 ef	34.81 ± 1.28	32.25 ± 1.61	18.16 ± 2.49	1.22 ± 0.21 klmn	3.74 ± 0.33 cdef
	Jipin pickled pepper	4.92 ± 0.16 a	14.47 ± 0.1 c	34.67 ± 1.13	31.47 ± 2.10	18.60 ± 1.47	1.21 ± 0.13l mn	4.89 ± 0.16 a
	21Z709	4.54 ± 0.01 b	11.07 ± 0.08 klmn	31.12 ± 0.9	31.01 ± 0.8	16.95 ± 0.7	2.72 ± 0.39 bc	4.62 ± 0.31 ab
	21Z656	3.82 ± 0.2d e	13.5 ± 0.39 ef	33.38 ± 1.3	32.88 ± 1.29	17.79 ± 0.96	1.09 ± 0.27 mn	4.55 ± 0.82 ab
	21Z682	3.75 ± 0.02 e	13.38 ± 0.31 ef	36.16 ± 2.38	37.37 ± 1.54	24.41 ± 3.84	1.63 ± 0.3 ghijklm	4.11 ± 0.26 bcd
	21Z698	3.21 ± 0.03 fg	10.57 ± 0.33 o	35.52 ± 1.36	38.77 ± 1.96	23.38 ± 2.41	1.63 ± 0.23 ghijklm	3.65 ± 0.26 cdefg
	21Z697	3.23 ± 0.09 f	13.35 ± 0.3 bef	34.92 ± 2.57	39.79 ± 1.76	24.45 ± 3.01	1.37 ± 0.3 jklmn	3.35 ± 0.45 efgh
	20Z647	4.82 ± 0.01 a	10.85 ± 0.1 mno	36.07 ± 1.16	39.87 ± 3.75	25.62 ± 3.25	1.02 ± 0.08 n	4.12 ± 0.39 bcd
	21Z675	4.05 ± 0.17 c	14.14 ± 0.25 cd	37.23 ± 1.51	36.41 ± 1.49	24.54 ± 2.5	1.36 ± 0.47 jklmn	3.8 ± 0.28 cdef
Horn pepper	21G17	2.73 ± 0.02 jkl	11.84 ± 0.51 ij	33.72 ± 1.96	32.96 ± 3.00	20.97 ± 3.35	1.62 ± 0.31 ghijklm	4.28 ± 0.42 abc
	21G12	2.72 ± 0.05 jklm	8.82 ± 0.18 rs	32.31 ± 1.15	31.96 ± 1.47	18.81 ± 1.28	2.06 ± 0.34 defg	4.31 ± 0.24 abc
Sharp pepper	21G50	3.18 ± 0.03 fg	11.42 ± 0.09 jkl	30.25 ± 0.86	27.12 ± 1.67	14.02 ± 1.14	1.94 ± 0.57 defghi	2.13 ± 0.13 j
	21G08	2.37 ± 0.05 nop	9.94 ± 0.35 p	34.42 ± 0.81	30.82 ± 1.46	19.47 ± 0.71	2.08 ± 0.25 defg	3.15 ± 0.16 efghi
	21G36	1.84 ± 0.03 q	10.63 ± 0.1 no	25.84 ± 3.12	9.29 ± 2.18	8.18 ± 1.01	2.44 ± 0.38 bcd	3.8 ± 0.48 cdef
Yellow pepper	21G62	2.75 ± 0.04 jkl	9.52 ± 0.11 pq	52.33 ± 1.18	23.77 ± 2.18	52.66 ± 2.71	1.89 ± 0.43 efghij	3.7 ± 0.34 cdefg
	21G59	3.04 ± 0.13 gh	9.24 ± 0.13 qr	53.26 ± 0.69	24.46 ± 2.01	53.08 ± 1.14	1.03 ± 0.2 n	3.14 ± 0.18 fghi
Jalapeño	21G226	1.95 ± 0.14 q	12.61 ± 0.16 g	28.04 ± 1.86	23.51 ± 2.14	12.29 ± 0.82	4.49 ± 0.32 a	3.85 ± 0.53 cde
	Max.	4.92	17.93	52.26	39.87	8.18	4.49	4.89
	Min.	1.81	6.45	25.84	9.29	53.08	1.02	2.13
	Average	3.01	11.71	33.56	30.84	20.64	1.8593	3.5382
	STD	0.89	2.39454	5.59	6.04	8.94	0.69	0.68
	CV%	29.64	24.43	16.65	19.58	43.31	37.62	19.40
Geno type	Code	Capsaicin (g/kg)	Dihydrocapsaicin (g/kg)	Moisture Content (%)	Cellulose (mg/g)	Vitamin C (mg/100 g))	Protein (g/100)	Soluble Glucose %
Line pepper	21G233	0.209 ± 0.02 k	0.062 ± 0.009 mnop	87.16 ± 0.15 l	24 ± 1.45 defg	54.12 ± 16.57 cdefgh	1.6 ± 0.01 defg	5.79 ± 0.01 jk
	21G27	0.204 ± 0.007 k	0.089 ± 0.008 ghijk	89.14 ± 1.16 hijk	22.64 ± 2.39 defghi	20.49 ± 0.63 h	0.95 ± 0.01 po	5.77 ± 0.01 k
	21 G47	0.212 ± 0.002 k	0.056 ± 0.005 opq	88.32 ± 1.29 ijkl	20.16 ± 2.35 efghijk	31.42 ± 5.72 efgh	0.96 ± 0.01 po	6.67 ± 0.01 c
	Bola hongniu	0.436 ± 0.007 c	0.155 ± 0.003 b	93 ± 0.36 de	23.33 ± 1.33	76.9 ± 13.98 cde	2.21 ± 0.01 a	5.84 ± 0.01 i
	21G07	0.240 ± 0.000 j	0.072 ± 0.003 klmno	87.92 ± 0.5 kl	24.48 ± 3.38	23.38 ± 3.3 fgh	1.24 ± 0.01 jklm	5.46 ± 0.02 n
	21G228	0.206 ± 0.000 k	0.063 ± 0.003 mnop	87.12 ± 0.79 l	31.44 ± 2.35 bc	62.77 ± 11.4 cdefgh	1.11 ± 0.01 lmno	5.44 ± 0.01 n
	21G77	0.092 ± 0.001 o	0.035 ± 0.000 rst	93.26 ± 0.14 d	39.27 ± 2.48 a	38.82 ± 26.19 efgh	1.39 ± 0.01 jhij	4.35 ± 0.01 s
	21G76	0.207 ± 0.003 k	0.058 ± 0.003 nopq	87.67 ± 0.28 kl	13.41 ± 0.97 lmn	54.14 ± 3.57 cdefgh	1.05 ± 0.01 on	5.92 ± 0.02 h
	21G10	0.085 ± 0.001 o	0.030 ± 0.000 t	88.33 ± 0.54 ijkl	24.78 ± 3.82 de	133.36 ± 23.26 ab	0.84 ± 0.01 qp	6.29 ± 0.01 e
	21G04	0.284 ± 0.007 h	0.088 ± 0.002 ghijk	88.31 ± 0.48 jkl	11.33 ± 0.96 n	55.08 ± 7.55 cdefgh	0.96 ± 0.02 po	6.72 ± 0.02 b
	21G229	0.335 ± 0.007 f	0.106 ± 0.004 efg	87.52 ± 0.63 kl	31.73 ± 0.83 bc	22.09 ± 2.73 gh	1.1 ± 0.01 onml	5.16 ± 0.01 pq
	21G73	0.273 ± 0.003 hi	0.092 ± 0.003 ghij	89.95 ± 0.2 ghij	12.56 ± 1.05 mn	38.51 ± 12.04 efgh	1.07 ± 0.00 onm	5.75 ± 0.01 kl
	21G03	0.034 ± 0.001 p	0.043 ± 0.001 qrst	86.72 ± 0.85 l	26.54 ± 3.22 cd	71.74 ± 16.67 cdef	0.69 ± 0.05 lq	6.09 ± 0.01 g
	21G43	0.200 ± 0.000 kl	0.076 ± 0.005 jklmn	87.17 ± 0.05 l	35.03 ± 4.29 ab	36.31 ± 11.17 efgh	1.32 ± 0.01 ijk	5.92 ± 0.01 h
	21G90	0.208 ± 0.000 lk	0.055 ± 0.004 opqr	86.74 ± 0.4 l	15.18 ± 3.58 defgh	71.59 ± 11.15 cdef	0.95 ± 0.01 po	5.82 ± 0.01 ij
	21G25	0.086 ± 0.001 o	0.033 ± 0.000 st	95.27 ± 0.12 bc	24.11 ± 0.7 de	37.67 ± 9.63 efgh	1.2 ± 0.00 klmn	5.36 ± 0.01 o
Pod pepper	21Z604	0.395 ± 0.002 d	0.154 ± 0.01 b	89.65 ± 2.18 ghij	13.44 ± 1.32 lmn	98.97 ± 19.86 bc	1.99 ± 0.01 b	6.12 ± 0.01 fg
	20Z663	0.636 ± 0.006 a	0.244 ± 0.000 a	90.77 ± 0.16 fg	17.93 ± 1.21 hijklm	61.54 ± 23.28 cdefgh	1.78 ± 0.01 c	6.64 ± 0.02 c
	20Z702	0.300 ± 0.00 g	0.1 ± 0 fghi	91.38 ± 0.16 ef	17.17 ± 1.87 ijklmn	69.36 ± 8.12 cdefg	1.69 ± 0.00 cde	7.12 ± 0.12 a
	Jipin pickled pepper	0.459 ± 0.008 b	0.102 ± 0.002 efgh	90.02 ± 2.46 fgh	33.63 ± 3.21 bc	21.45 ± 2.35 gh	1.55 ± 0.01 defg	5.83 ± 0.01 ij
	21Z709	0.184 ± 0.003 m	0.082 ± 0.002 ijklm	95.12 ± 0.06 bc	21.96 ± 2.88 defghij	35.7 ± 7.11 efgh	1.21 ± 0.02 jklmn	4.66 ± 0.03 r
	21Z656	0.335 ± 0.004 f	0.121 ± 0 de	93.18 ± 0.15 d	14 ± 2.23 lmn	96.86 ± 38.62 bc	1.52 ± 0.01 edgh	5.2 ± 0.01 p
	21Z682	0.284 ± 0.001 h	0.103 ± 0.003 efgh	96.28 ± 0.2 b	18.54 ± 3.26 fghijklm	22.54 ± 0.67 gh	1.7 ± 0.01 cd	6.15 ± 0.01 f
	21Z698	0.21 ± 0.001 k	0.068 ± 0.005 lmnop	87.37 ± 0.06 l	22.58 ± 3.61 defghi	67.84 ± 19.56 cdefg	1.69 ± 0.01 cde	5.48 ± 0.01 n
	21Z697	0.438 ± 0.007 c	0.15 ± 0.004 bc	90.08 ± 1.18 fgh	11.7 ± 2.19 n	30.14 ± 1.58 efgh	1.65 ± 0.01 cde	5.7 ± 0.02 k
	20Z647	0.05 ± 0.004 d	0.159 ± 0.001 b	93.44 ± 0.08 d	33.17 ± 3.3 b	92.43 ± 23.49 bcd	1.59 ± 0.01 def	5.75 ± 0.01 kl
	21Z675	0.357 ± 0.00 e	0.131 ± 0 cd	96.1 ± 0.03 a	21.59 ± 1.43 defghij	20.31 ± 0.36 h	1.97 ± 0.01 b	5.7 ± 0.00 l
Horn pepper	21G17	0.442 ± 0.024 c	0.105 ± 0.007 efg	92.76 ± 0.72 de	26.1 ± 0.37 cd	38.22 ± 17.39 efgh	1.43 ± 0.01 fghi	5.59 ± 0.01 m
	21G12	0.205 ± 0.004 k	0.085 ± 0.005 hijkl	87.01 ± 0.62 l	12.73 ± 3.74 lmn	170.71 ± 41.04 a	1.37 ± 0.01 hijk	5.39 ± 0.01 o
Sharp pepper	21G50	0.189 ± 0.005 lm	0.12 ± 0.007 def	85.04 ± 1.16 m	12 ± 4.62 n	62.64 ± 25.22 cdefgh	1.24 ± 0.01 jklm	4.04 ± 0.00 t
	21G08	0.140 ± 0.006 n	0.040 ± 0.001 qrsst	87.5 ± 0.76 l	11.54 ± 2.24 n	22.33 ± 9.34 gh	0.83 ± 0.01 qp	5.76 ± 0.01 k
	21G36	0.139 ± 0.001 n	0.051 ± 0.001 pqrs	88.1 ± 0.36 jkl	24.29 ± 0.04 def	26.27 ± 8.33 fgh	1.2 ± 0.01 klmn	5.14 ± 0.01 q
Yellow pepper	21G59	0.329 ± 0.001 f	0.081 ± 0.001 ijklm	91.09 ± 0.03 fg	18.17 ± 0.21 ghijklm	170.23 ± 21.8 a	1.73 ± 0.01 cd	3.99 ± 0.01 t
	21G62	0.404 ± 0.006 d	0.127 ± 0.005 d	87.82 ± 0.01 kl	16.58 ± 5.08 jklmn	24.85 ± 7.72 fgh	1.28 ± 0.01 ijkl	4.7 ± 0.01 r
Jalapeño	21G226	0.261 ± 0.003 i	0.113 ± 0.003 def	93.87 ± 0.45 cd	15.02 ± 0.46 klmn	43.89 ± 9.25 degh	1.1 ± 0.02 lmno	6.37 ± 0.03 d
	Max.	0.636	0.244	96.28	39.27	170.71	2.21	7.12
	Min.	0.034	0.159	85.04	11.33	20.31	0.83	3.99
	Average	0.269	0.09281	0.90	21.20	57.27	1.34	5.67
	STD	0.128	0.045	0.035	7.88	43.27	0.36	0.72
	CV%	48.02	48.70	3.88	37.16	75.54	27.34	12.75

Abbreviation: Maximum—Max.; Minimum—Min., Standard Deviation—STD, Coefficient of Variation—CV. Notes: Different letters show significant difference level.

shows differences in FCP quality, as indicated by several variables. There was a significant difference in 14 indexes, notably vitamin C (Vc), capsaicin, b*, cellulose, total acids, protein, protopectin, and fruit thickness, with correlative coefficients of 75.54%, 48.02%, 48.70%, 37.62%, 37.16%, 29.64%, 27.34%, and 24.43%, respectively. The fruit thickness, protein, total acid, and protopectin values were comparatively high in the pod pepper, and the color was a bright red. A large difference was also found in capsaicin, Vc, and cellulose, but this showed no obvious relationship [19,20].

3.2. Correlation Analysis of the Quality of FCPs with Different Genotypes

In Figure 1, red represents a positive correlation, and blue represents a negative correlation; darker colors and narrower ovals indicate a greater correlation between the indexes. As per Figure 2, the main results are as follows: (1) There is a significant positive correlation between protein, capsaicin, dihydrocapsaicin, total acids, and color; this indicates that protein and total acids are the main soluble solids in chili peppers, and the higher the soluble solid content, the richer the chili pepper’s flavor. (2) L represents the degree of color in the peel and was significantly positively correlated with b*, representing the yellow–blue relationship. This explains why red chili peppers are always very bright, which enhances related products. (3) The fruit thickness was negatively correlated with total acids, L* a* b*, capsaicin, and protein. Fruit thickness is based on the maturity of the chili pepper; when the chili pepper is overmature, the other indexes will decline, and thus, the quality will also decline. (4) Capsaicin and dihydrocapsaicin shared a significant correlation; the more capsaicin was in the chili pepper, the more dihydrocapsaicin there was. This shows that these two compounds are representative of hotness in chili peppers.

3.3. PCA of the Quality Indexes of FCP with Different Genotypes

PCA was adopted to analyze 14 indexes of the 35 chili pepper varieties (Table S3). The characteristic values of the first five components were greater than one, and the cumulative variance contribution rate was 72.90%, reflecting the most information for the original variable; thus, the five components could be regarded as the main quality appraisal index. In Table S4, the red numbers indicate the indexes with the greatest load. Capsaicin, dihydrocapsaicin, protein, total acids, thickness, and a* were the indexes with the greatest load in the first principal component; therefore, they affected the quality more than the other product attributes. Except for thickness, these indexes were positively correlated.

Table S5 shows five equations corresponding to the five principal components, as follows:

F₁ = 0.394 × X₁ + 0.392 × X₂ + 0.374 × X₃ + 0.359 × X₄ − 0.309 × X₅ + 0.266 × X₆ + 0.214 × X₇+ 0.237 × X₈ + 0.03 × X₉ + 0.203 × X₁₀ − 0.039 × X₁₁ + 0.238 × X₁₂ + 0.215 × X₁₃ + 0.088 × X₁₄

F₂ = 0.035 × X₁ + 0.081 × X₂ + 0.144 × X₃ + 0.12 × X₄ + 0.15 × X₅ − 0.078 × X₆ − 0.512 × X₇ − 0.496 × X₈ + 0.421 × X₉ + 0.38 × X₁₀ + 0.079 × X₁₁ − 0.11 × X₁₂ + 0.155 × X₁₃ − 0.264 × X₁₄

F₃ = 0.04 × X₁ − 0.203 × X₂ − 0.259 × X₃ + 0.191 × X₄ + 0.045 × X₅ − 0.004 × X₆ − 0.049 × X₇ − 0.014 × X₈ − 0.295 × X₉ − 0.175 × X₁₀ + 0.555 × X₁₁ + 0.464 × X₁₂ + 0.423 × X₁₃ − 0.171 × X₁₄

F₄ = −0.142 × X₁ − 0.271 × X₂ − 0.237 × X₃ + 0.081 × X₄ + 0.02 × X₅ + 0.42 × X₆ − 0.073 × X₇ − 0.049 × X₈ + 0.305 × X₉ − 0.167 × X₁₀ − 0.359 × X₁₁ + 0.122 × X₁₂ + 0.377 × X₁₃ + 0.503 × X₁₄

F₅ = −0.05 × X₁ + 0.177 × X₂ + 0.167 × X₃ − 0.235 × X₄ + 0.524 × X₅ − 0.259 × X₆ + 0.156 × X₇+ 0.146 × X₈ + 0.043 × X₉ − 0.09 × X₁₀ − 0.432 × X₁₁ + 0.406 × X₁₂ + 0.278 × X₁₃ − 0.241 × X₁₄

where X₁ is capsaicin, X₂ is protein, X₃ is dihydrocapsaicin, X₄ is total acids, X₅ is thickness, X₆ is a*, X₇ is b*, X₈ is L, X₉ is soluble total glucose, X₁₀ is protopectin, X₁₁ is cellulose, X₁₂ is water, X₁₃ is Vc, and X₁₄ is hardness.

The scores of the five components were multiplied by the variance contribution rate and then added together to obtain the function for a comprehensive assessment, as follows:

$$Y=31.63F_1+17.84F_2+10.538F_3+7.937F_4+7.693F_5$$

The indexes of the 35 chili pepper varieties were processed without dimensionalization or standardization and then calculated using the aforementioned formula to obtain the scores in Table S6. The pod pepper scores were generally higher, and pod pepper 20Z663 had the highest scores. Except for Bolahongniu, a line pepper, the peppers with the top 10 highest scores were pod peppers.

3.4. Cluster Analysis of the Quality of Fresh Chili Pepper by Different Genotypes

In Figure 3, the chili pepper varieties are arranged into four clusters. The first cluster is 21G226, with high water content and a fruit thickness of 4.49 mm. The second cluster includes 21 species from 21G47 to 21G43, which are lower in capsaicin and have an average content of 0.18 ± 0.71 g/kg. In the third cluster, there are 11 species: Bolahongniu, 21Z604, 21Z702, 21Z682, 21Z675, 21G17, 21Z656, 21Z656, Jipin pickled peppers, 20Z647, and 20Z663. Except for 21G17 and Bolahongniu, these are pod peppers. The chili peppers in this cluster have higher protein and total acids, with a thin fruit thickness and bright red color. The fourth cluster is 21G62 and 21G59, which are considered yellow chili peppers given their color [21,22]. Each cluster has a distinct characteristic: the first cluster has the lowest quality, the second cluster has the lowest hotness, the third cluster mostly includes pod peppers, and the fourth cluster has a different color. From the four clusters, 17 varieties of chili pepper were selected as representatives to produce FCCP and to find suitable varieties for it; this research will also elucidate the main indexes that affect this product.

3.5. Processing Adaptability Appraisal of Fresh Chili Peppers of Different Genotypes

3.5.1. Sensory Appraisal Results of FCCP

A sensory appraisal was used to describe FCCP quality. Seven appraisal indexes were counted, including color, aroma, taste, form, and crispness. As shown in the radar plot (Figure 4), most FCCP products look good in taste, aroma, color, and form, but the greatest difference is in the crispness. The crispness varies from the center to the periphery, which shows the greatest attribute of FCCP. As discussed by Liu et al. [23], crispness is the most important mouthfeel sensation and can decrease during the process. The varieties with the top three scores were A12 (21G675), A13 (20Z663), and A14 (21Z698) with scores of 87.92, 74.08, and 74.15, respectively. A12 (21G675) is superior to the other products in all attributes and the varieties in the top three scores are pod peppers. The FCCP is made from FCPs with a particular salt concentration. Soluble substances, such as protein and glucose, exude from the chili pepper via osmotic pressure and then undergo a series of changes owing to the effects of microbes and enzymes; thus, the characteristic flavor of FCCP is finally formed. These results indicate that FCCP with good flavor comes from using high-quality FCPs, but high-quality FCPs do not necessarily produce FCCP with a good flavor.

3.5.2. Key Index Screening in Process Adaptability of FCCP

In Table S6, the red numbers are significant positive correlation coefficients, and the results are as follows: (1) The color of the FCCP originated from its fresh material (p < 0.05). (2) Protein (p < 0.01) and total acids (p < 0.01/p < 0.05) were the most important factors affecting the aroma, taste, form, and crispness of FCCP, indicating that higher protein and total acid contents improved its flavor. (3) Protopectin (p < 0.01) only affected crispness, and water content (p < 0.01) only affected aroma. (4) Fruit thickness (p < 0.05) was the only factor with a negative correlation with most of the sensory indexes, indicating that thinner peels improve the quality of FCCP. (5) Protein, total acids, a*, protopectin, and fruit thickness were the top five most influential key indexes in FCCP sensory outcomes [24].

The screening results of the stepwise regression analysis are shown in Table S7. The top five indexes that affected the quality of FCCP were protein, total acids, a*, protopectin, and fruit thickness, which are the same as the results from the correlation analysis above. Therefore, we determined that these are the key indexes for appraising the process adaptability of fresh chili peppers.

3.5.3. Process Adaptability Appraisal of FCCP

We appraised fresh chili peppers based on the top five indexes identified above; the results are shown in Table S8. The results are as follows: (1) There was no significant difference within the same level, between the first two levels, or between the last two levels, indicating that the closer the key indexes of fresh chili peppers, the more similar the FCCP quality. (2) There was a significant difference between the first and second levels and the third and fourth levels (p < 0.05), indicating that the more different the indexes, the more different the quality. Based on the variation in the first level, the key index ranges are shown in Table S9, and the sensory appraisal results and appraisal standard are shown in Table S10. The most suitable chili peppers for FCCP were 20Z647, 21Z698, 21Z663, 21Z675, Bolahongniu, 21G33, and 21G288 [25].

3.5.4. Verification of FCCP via Cluster Analysis

A cluster analysis of the five key indexes—color, aroma, taste, form, and crispness—using the Euclidean distance method is shown in Figure 5. Cluster 1 included Bolahongniu, 21G233, 21G288, 20Z647, 21Z698, 21G77, and 21Z663; cluster 2 includes 21G04, 21G27, 21G10, 21G07, 21G229, 21G226, and 21G76; cluster 3 includes 21Z675; and cluster 4 includes 21G36 and 21G08.

The cluster analysis statistical results for the sensory appraisal indexes are shown in

Table 2. Cluster analysis of sensory appraisal indexes of FCCP.

Cluster		Color	Aroma	Taste	Form	Crispness	Score
Cluster 1	Ave.	13.19 ± 1.77	15.10 ± 0.45	15.23 ± 0.66	15.09 ± 1.18	13.21 ± 1.62	71.50 ± 1.78
	Max.	15.08	15.69	16.08	16.15	16.31	74.15
	Min.	10.38	14.62	14.62	13.31	11.85	69.62
Cluster 2	Ave.	15.23 ± 1.60	13.18 ± 1.00	13.50 ± 1.60	12.82 ± 1.27	9.05 ± 1.41	63.89 ± 4.91
	Max.	17.23	15.46	16.08	14.54	11.23	71.85
	Min.	12.15	12.31	10.46	11.23	7.08	55.08
Cluster 3	Ave.	18.46 ± 0.00	16.92 ± 0.00	17.85 ± 0.00	18.08 ± 0.00	16.62 ± 0.00	87.92 ± 0.00
	Max.	18.46	16.92	17.84	18.08	16.62	87.92
	Min.	18.46	16.92	17.84	18.08	16.62	87.92
Cluster 4	Ave.	5.54 ± 0.00	12.77 ± 0.00	9.92 ± 0.00	11.15 ± 0.00	6.31 ± 0.00	45.69 ± 0.00
	Max.	5.54	12.77	9.92	11.15	6.31	45.69
	Min.	5.54	12.77	9.92	11.15	6.31	45.69

, with the descending average score as follows: 87.92 (cluster 3) > 71.50 (cluster 1) > 63.89 (cluster 2) > 45.69 (cluster 4).

The results showed a significant difference in the color and crispness indexes, but there was a less significant difference in the color and taste between clusters 1 and 2 and the form index between clusters 2 and 4 [26].

4. Conclusions

The quality of FCCP is related to fermentation microbes, processing technology, and FCPs. To create controlled fermentation surroundings and procedures, we specifically focused on the influence of different varieties on the quality of FCCP. We selected 17 representative varieties of FCPs to make FCCP. Through a correlation analysis between FCPs and FCCP, combined with sensory evaluation, we found that protein, total acids, a*, protopectin, and fruit thickness were the five key indexes that affect the quality of FCPs the most. Furthermore, these indexes were also found to be the key indexes that affect the quality of FCCP. Our composition analysis showed that the suitable ranges for fresh chili peppers in the process of making FCCP were 1.3–2.0 g/100 g for protein, 2.5–4.0 g/kg for total acids, 10–15 g/100 g for protopectin, 30–39 for a*, and 1.2–2.0 mm for fruit thickness. These indexes can be used to appraise the process adaptability of chili peppers for FCCP, and breeding can be directed to emphasize these indexes and their ranges. During our screening of the 35 FCP varieties, we also concluded that pod peppers were the most suitable varieties for making FCCP, which has also been determined by more and more enterprises. In the future, we will conduct research to explore the correlation between microbes and process technologies, to obtain a clearer image of how to select suitable varieties for making FCCP.