Curcubita moschata Seeds: Ancestral Flavor and Nutrition for Current Use

Abstract

The squash, C. moschata, is a type of pumpkin that grows easily in milpas—small, polyculture fields in Guatemala. Excavations carried out in pre-Columbian mounds in Uaxactún, Petén, indicate that squash has been cultivated and consumed for more than 5000 years. Today, both the pulp and the seed are still used as food; seeds are processed by hand and sold as toasted seed, or as toasted and ground seed with added salt, which is called pepita. The seed is used as a flavoring and thickening ingredient in sauces and pepita is used as an accompaniment to fresh fruit. This work aimed to provide updated information on the nutritional compositions of squash seeds and pepita in popular markets in the north, center, west, and southeast of Guatemala. The moisture content was determined in a convection oven at 60 °C, the ash by combustion in furnace at 450 °C, the protein by Kjeldahl method, fat by solvent extraction in the goldfish apparatus, and minerals by atomic absorption spectroscopy; and a UV/VIS colorimeter. The moisture content in seeds and pepita were 5.67% and 4.65%; ash 4% and 6.24%; protein 32.9% and 29.21%; lipids 32.07% and 30.22%, respectively. There was a higher content of macrominerals in pepita than in seeds, due to the salt addition. Comparing the nutritional results of the dry seed with those reported in the Food Composition Table for Central America, differences in protein and fat content are greater than 10%.

1. Introduction

Ayote is a type of squash that grows as a creeping plant in corn fields in Guatemala. It belongs to the Cucurbitaceae family, and its scientific name is Cucurbita moschata Duchesne. Guatemala is the point of origin of Cucurbita moschata D [1]; there are archaeological records that mention C. moschata as a plant cultivated and consumed in Guatemala for more than 5000 years [2]; in excavations carried out in pre-Columbian mounds, in Uaxactún, Petén, researchers found carbonized peduncles of C. moschata [2].

The cultivation of squash is part of the Mesoamerican food system known as milpa, which includes the cultivation of corn, beans, and squash in the same physical space and in biological harmony, which allows the spontaneous growth of a variety of herbs with edible leaves and stems that, together, are called quiletes [3].

Both the flowers and the tender stems of the ayote, the immature fruits, the mature fruits, and its seeds are edible. Squash seeds are abundant, extracted from the ripe fruit and easily dried in the sun or at room temperature. The seeds are usually toasted and consumed as a snack, but they can also be ground and added as a thickening agent to sauces. The sauce known as “iguashte” in Spanish, or Ch’ereb’an in Kaqchiquel, is prepared from these seeds; it is a thick sauce obtained from squash seeds blended in the water used to boil meats or vegetables, seasoned with salt and chili. Approximately one ounce of toasted squash seeds is used per serving of vegetables or meat [3].

Another popular way in which squash seeds are consumed is as “pepita”. Pepita is prepared using artisanal methods: people toast them on a clay or metal pan, grind them in a disc mill, and then add salt. The most frequent use of the pepita is to accompany pieces of fresh fruit, which are sold on the street. Normally, a teaspoon of pepita is added per 250 g portion of fruit.

Due to the importance of seeds in the diet, the frequent use of squash seeds in the Guatemalan diet and the lack of information on pepita’s nutritional composition, we present this study to provide more data on the nutritional composition of the squash seed and the pepita sold in popular markets in five regions of Guatemala.

2. Materials and Methods

2.1. Sample Collection

The squash seeds and pepita were obtained in bulk from five markets of Guatemala: Flores and Santa Cruz del Quiché (northern region), Jutiapa (southern region), Jacaltenango (western region), and Santiago Atitlán, (central region).

2.2. Macronutrient and Minerals Quantification

The proximal composition was determined by official techniques. The analysis matrix was dried and pulverized squash seed, and dried and pulverized pepita, both with a particle size of 0.5 mm. The humidity was determined in a convection oven at 60 °C until it was a constant weight; the ash by muffle at 450 °C, the raw protein by the Kjeldhal method using Kjeltec Auto 1030 Analyzer equipment; the lipids by petroleum benzene extraction using Goldfish equipment. The minerals were determined by atomic absorption spectroscopy, using Perkin Elmer AAnalyst 100 equipment, except phosphorus, which was determined using a UV/VIS Lambda 11 colorimeter. The analyses were conducted in triplicate.

2.3. Statistical Analysis

Macronutrient and mineral content results were expressed as mean +/− standard deviation. The results were analyzed using descriptive statistics and analysis of variance -ANOVA + post hoc to determine statistically significant differences, through the Statgraphics Centurion19.

3. Results and Discussion

3.1. Macronutrients and Minerals in Cucurbita Moschata Seeds

Table 1. Macronutrients (g/100 g) and minerals (mg/100 g) in C. moschata seeds.

	Jutiapa	Flores, Petén	Santa Cruz, Quiché	Jacaltenango	Santiago Atitlán	Media
Water	3.61 ± 0.09 a	4.79 ± 0.03 b	5.34 ± 0.19 c	6.47 ± 0.09 d	6.56 ± 0.10 d	5.35 ± 1.1
Ash	4.76 ± 0.08 d	3.90 ± 0.02 b	4.12 ± 0.07 c	3.50 ± 0.04 a	3.40 ± 0.07 a	3.9 ± 0.5
Lipids	30.59 ± 0.04 b	32.78 ± 0.02 d	32.23 ± 0.05 c	29.31 ± 0.05 a	32.31 ± 0.06 c	31.44 ± 0.9
Protein	35.39 ± 0.05 e	30.08 ± 0.3 a	33.64 ± 0.06 c	35.68 ± 0.05 d	33.35 ± 0.05 b	33.63 ± 1.9
Calcium	80 ± 0 a	100 ± 0 c	80 ± 0 a	90 ± 0 b	80 ± 0 a	86 ± 0
Phosphorus	73 ± 5.7 b	73 ± 5.7 b	63 ± 5.7 a	110 ± 0 c	63 ± 5.7 a	76.6 ± 19.3
Sodium	20 ± 0 a	21 ± 0 a	22 ± 0 a	23 ± 0 a	24 ± 0 a	22 ± 0
Potassium	630 ± 0 c	690 ± 0 d	690 ± 0 d	480 ± 34.6 b	440 ± 0 a	586 ± 118
Magnesium	380 ± 0 d	330 ± 0 b	350 ± 0 c	310 ± 0 a	323 ± 11.5 b	338.6 ± 27.24
Iron	8.0 ± 0 c	7.6 ± 0.28 c	5.8 ± 0.28 a	6.5 ± 0 b	6.6 ± 0.28 b	6.09 ± 0.88
Coper	0.1 ± 0 a	0.36 ± 0.23 b	0.1 ± 0 a	0.1 ± 0 a	0.5 ± 0 b	0.23 ± 0.18
Zinc	6.0 ± 0 c	7.2 ± 0.28 e	5.2 ± 0.28 a	5.5 ± 0 b	6.5 ± 0 d	6.1 ± 0.79
Manganese	4.83 ± 0.57 c	1.16 ± 0.28 a	2.83 ± 0.28 b	2.5 ± 0 b	3.0 ± 0 b	2.8 ± 1.31

Different letters in the superscripts, between columns, indicate significant differences (p ≤ 0.05).

shows the macronutrients and mineral content of C. moschata seeds from different regions. Squash seeds had high protein and lipid and low water content. This is characteristic of all seeds, since they must accumulate reserve nutrients for germination purposes [4].

The protein content was in the range of 30 to 35%. Squash seeds from Flores, Petén had the lowest value. This amount of protein is similar to that reported in code 10015 of the Central American Food Composition Table, and in code 12014 of the USDA database, for dried squash seeds and raw pumpkin seeds, respectively [5,6].

The average lipid content was 31.44% and the range was between 29.31% and 32.78%. The lowest content was found in squash seeds from Jacaltenango. In general, the amount of lipids in squash seeds was high, but it was observed that there was 10 to 15% lower lipid content compared to data from the food composition tables and databases [5,6]. Alfawaz [7] and Manda Devi, Prassad and Palmei [8] analyzed the nutritional composition of whole pumpkin seeds and kernels and found 28–32% of lipids in whole seeds and 32–44% in kernels. Petkova and Antova [9] studied the protein and lipid content in C. moschata seeds at 30, 60, and 90 days of post-flowering growth, and found that the concentration of both nutrients is directly related to the post-flowering time. This could explain the difference found in this study, given that the seeds analyzed were whole seeds, and probably the maturity level of the fruit from which the seeds were extracted was around 45 days post-flowering growth.

High variability was observed in the copper, manganese, and phosphorus concentrations based on where the seeds were purchased. When compared with food composition tables and databases [5,6], there was a lower concentration of phosphorus, potassium, and magnesium in the seeds from Guatemala.

3.2. Macronutrients and Minerals in Pepita

Table 2. Macronutrients (g/100 g) and minerals (mg/100 g) in pepita.

	Jutiapa	Flores, Petén	Santa Cruz, Quiché	Jacaltenango	Santiago Atitlán	Media
Water	4.45 ± 0.1 b	2.53 ± 0.08 a	4.69 ± 0.14 b	5.61 ± 0.28 c	5.97 ± 0.94 c	4.65 ± 1.39
Ash	9.43 ± 0.07 d	4.21 ± 0.03 b	9.35 ± 0.07 d	3.72 ± 0.03 a	4.52 ± 0.06 c	6.25 ± 2.88
Lipids	31.38 ± 0.06 c	32.65 ± 0.04 d	35.51 ± 0.04 e	28.32 ± 0.10 b	23.26 ± 0.11 a	30.22 ± 4.67
Protein	21.06 ± 0.02 a	32.61 ± 0.04 d	28.73 ± 0.04 b	33.46 ± 0.03 e	30.21 ± 0.03 c	29.21 ± 4.92
Calcium	100 ± 0 b	90 ± 0 a	120 ± 0 c	123 ± 5.7 c	250 ± 0 d	136 ± 64.8
Phosphorus	80 ± 0 b	73 ± 5.7 b	103 ± 5.7 c	63 ± 5.7 a	103 ± 5.7 c	84.6 ± 18.0
Sodium	2130 ± 0 e	20 ± 0 a	1320 ± 0 d	60 ± 0 b	880 ± 0 c	882 ± 889
Potassium	920 ± 34.64 e	690 ± 0 c	810 ± 0 d	650 ± 0 b	530 ± 0 a	720 ± 150
Magnesium	350 ± 0 c	380 ± 0 d	430 ± 0 e	280 ± 0 b	160 ± 0 a	320 ± 104.6
Iron	5.0 ± 0 c	6.66 ± 0.28 d	4.33 ± 0.28 b	2.0 ± 0 a	4.5 ± 0 b	4.5 ± 1.7
Coper	0.1 ± 0 a	0.23 ± 0.23 a	0.1 ± 0 a	0.1 ± 0 a	0.1 ± 0 a	0.12 ± 0.05
Zinc	3.5 ± 0 c	5.5 ± 0 e	1.5 ± 0 a	3.0 ± 0 b	5.2 ± 0.29 d	3.73 ± 1.64
Manganese	1.0 ± 0 b	3.0 ± 0 c	0.5 ± 0 a	3.5 ± 0 d	3.0 ± 0 c	2.2 ± 1.3

Different letters in the superscripts, between columns, indicate significant differences (p < 0.05).

shows the macronutrient and mineral content of pepita from different places.

It was observed that the pepita from Jutiapa and Santa Cruz del Quiché had twice the ash as those from other origins; it was also observed that the pepita from Flores, Petén, did not show variation in sodium content when compared to the other seeds, which can be interpreted as meaning that no salt was added. This is related to observations about the pepita’s sodium content and other minerals, which increase from 50 to 100 times. Except for iron and copper, it was observed that all minerals had higher concentrations in the pepita than in the seed.

The bioavailability of minerals and protein in the pumpkin seed is expected to improve when the seed is ground into coarse flour, since the physical structure of the seed is broken and the external protective layers are disintegrated, which allows a greater surface area of contact between the tissues and digestive enzymes.

When comparing the average content of macronutrients and minerals in pumpkin seed and pepita (

Table 3. Media of macronutrients and minerals in C. moschata seeds and pepita.

	Seeds	Pepita
Water	5.35 ± 1.1	4.65 ± 1.39
Ash	3.9 ± 0.5	6.25 ± 2.88
Fat	31.44 ± 0.9	30.22 ± 4.67
Protein	33.63 ± 1.9	29.21 ± 4.92
Calcium	86 ± 0	136 ± 64.8
Phosphorus	76.6 ± 19.3	84.6 ± 18.0
Sodium	22 ± 0	882 ± 889
Potassium	586 ± 118	720 ± 150
Magnesium	338.6 ± 27.24	320 ± 104.6
Iron	6.09 ± 0.88	4.5 ± 1.7
Coper	0.23 ± 0.18	0.12 ± 0.05
Zinc	6.1 ± 0.79	3.73 ± 1.64
Manganese	2.8 ± 1.31	2.2 ± 1.3

), the main differences were found in minerals, because the preparation of the pepita includes the addition of salt. Although the differences in macronutrient and mineral contents were not significant, the mathematical differences in sodium content were notable; since the sodium concentration was in the range of 20 to 2130 mg/100 g, this means a range of 1 to 166 mg of sodium per teaspoon of pumpkin seed.

4. Conclusions

Pumpkin seeds and pepita have nutritional characteristics that have been valued for thousands of years. Today, pumpkin seeds are consumed as an ingredient in sauces or an accompaniment to fruit. This study found differences in the macronutrient and mineral content of pumpkin seeds and pepita, depending on their origin. Its high protein, fat, and sodium content were also found, particularly in the pepita, due to its artisanal production.