Page 1 of 9
European Journal of Applied Sciences – Vol. 10, No. 5
Publication Date: October 25, 2022
DOI:10.14738/aivp.105.13169. Kinkela, N., Mpanda, K., & Metos, N. N. (2022). Transformation of Fresh Tomato Into Powder and its Conservation by the Artisanal
Drying Method in the Province of Uige in Angola. European Journal of Applied Sciences, 10(5). 222-230.
Services for Science and Education – United Kingdom
Transformation of Fresh Tomato Into Powder and its
Conservation by the Artisanal Drying Method in the Province of
Uige in Angola
Nswadi Kinkela
Polytechnic Institute of the Kimpa Vita University
Uíge, Angola CP. 77
Kundakama Mpanda
Polytechnic Institute of the Kimpa Vita University
Uíge, Angola CP. 77
Nwadi Nsayi Metos
Pedagogical Institute of Mbanza-Ngungu
Democratic Republic of Congo, BP. 127
ABSTRACT
Tomato is a plant belonging to the Solanaceae family, scientifically named
Lycopersicum esculentum Mill. Essential for the agricultural industry; the tomato is
one of the most cultivated and consumed used agricultural products by most of the
population of the province of Uige in Angola. It has excellent nutritional value, rich
in vitamins, lycopene, and mineral salts, and can be eaten fresh or processed. The
tomato is essential not only for its nutrients but also for its health benefits [9]. When
making field observations, two aspects caught our attention: When large quantities
of tomatoes are produced but not sold, we noticed that the rest of the merchandise
gets rotted due to their water content. On the other hand, almost all markets and
supermarkets in Uige sell fresh tomato and other tomato products (tomato paste,
ketchup, etc.). However, there is a shortage of tomato powder in the market. Thus,
this research aims to transform fresh tomato into powder, analyze the quality of the
powder, conserve it to minimize post-harvest losses, and at the same time offer a
different sensory product to the population of Uige. In order to achieve the objective
of our research, we have built a small-scale greenhouse for drying fresh tomatoes.
The tomato powder was taken to the chemical laboratory of Kimpa Vita University
(Uige/Angola) for chemical analysis of the product stored for 75days. Organoleptic
analyses, such as glycogen content (reducing sugars), titratable acidity, pH, and
moisture content, were carried out. In addition, the identification of some
phytochemical substances such as flavonoids, lycopene, anthocyanins, and reducing
sugar. The samples analyzed within the 75 days of storage presented the following
results: The colour remained light red from day 1 to day 48, and from December 9th
to the end of the experiment, it changed to dark red. Odour and taste changed from
very good to good. The texture remained powdery. During the identification of
chemical substances, we found flavonoids, lycopene, and glycides in the tomato
poder. As for the physical-chemical parameters, the following averages were
obtained respectively: pH: 4.02, acidity in citric acid:0.4%, moisture content:
36.6%, Glucose content:4.46%.
Page 2 of 9
223
Kinkela, N., Mpanda, K., & Metos, N. N. (2022). Transformation of Fresh Tomato Into Powder and its Conservation by the Artisanal Drying Method
in the Province of Uige in Angola. European Journal of Applied Sciences, 10(5). 222-230.
URL: http://dx.doi.org/10.14738/aivp.105.13169
Keywords: tomato, processing, drying, conservation, chemical analysis.
INTRODUCTION
Food is essential for life because human health depends on it (SESC , 2003). For millions of
years, most foods (agricultural products) were harvested and consumed almost immediately
so that they do not decompose and endanger human health.
However, "only" about two hundred years ago, a fast and sustained evolution in human
nutrition began. Around this time, the first step was taken to create an industry devoted to
transforming and conserving food (agricultural products).
This technological innovation made it possible to guarantee the preservation of foodstuffs for
more extended periods. Thus, it became possible to do the following:
- Storing foods that will be consumed during shortage;
- Transport certain foods to places where their consumption was not possible due to their
perishable nature and the lack of proper transportation conditions;
- To provide consumers with new flavours of agri-food products
Among the vegetables grown worldwide for consumption in nature and, above all,
industrialized, the tomato (LycopersiconesculentumMill), a vegetable whose edible part is the
fruit, stands out, the reason why it is considered of universal production and use. This
climacteric fruit is highly perishable; thus, conservation techniques in post-harvest can
contribute to minimizing its losses and adding value). [1]
Tomato (Solanum Lycopersicum L) is a fruit of great socio-economic importance and an
important source of minerals, vitamins, and antioxidant pigments such as lycopene. A study of
over 47,000 men showed that those who consumed tomato products ten times or more per
week had less than half the risk of developing advanced prostate cancer. [6]
Thus, a diet rich in lycopene is essential to reduce the risk of developing various types of cancer
and cardiovascular diseases.
However, this fruit is quite perishable, and with a relatively short shelf life, post-harvest losses
are very high (25% - 50%) compared to other vegetables. These are among the significant
problems faced by farmers, wholesale traders, and consumers. [5]
Post-harvest preservation methods for tomatoes can contribute to minimizing losses. One of
these methods is drying. Drying is one of the oldest methods of food preservation; it consists of
eliminating water from the food. There are two methods of drying: the natural, which is done
in the sun, and the artificial, which needs energy supply, different from the solar one. [4]
Tomato powder is obtained by grinding dried tomatoes; this has several advantages, such as
ease of packaging, transport, and handling. It can be reconstituted into pulp or juice and used
as a base for preparing products such as sauce, ketchup, soups, seasonings, etc.
Page 3 of 9
224
European Journal of Applied Sciences (EJAS) Vol. 10, Issue 5, October-2022
Services for Science and Education – United Kingdom
The quality of tomato powder depends on the characteristics of the raw material and the drying
process. Therefore, the study of the efficiency of the drying method and the factors influencing
the quality of dehydrated products is essential to establish the best process condition to obtain
a high-quality product. [10]
It is necessary to analyze the quality parameters to know the conservation status of tomato
powder. Several researchers studied physicochemical parameters and summarized them in the
table below.
Table 1: Quality parameters of tomato powder
Parameter Values
pH 4,0 – 4,5 (ácid)
Soluble solids 4,3 – 5,4 (salad/italian tomato)
8,0 (sweeter mini tomato)
Acidity in citric acid (g/100g) 0,33 – 0,5
Vitamin C (mg/100g) 21,2
Lycopene (mg/g) 60 – 80
Potassium (mg/100g) 22,0
Source : [11]
MATERIALS AND METHODS
Origin of raw material
We used tomato fruits of the Italian variety purchased at the conventional market fair in the
municipality of Uige /Angola.
Tomatoes were selected according to the following criteria:
Ø Intense red colouration in the skin and pulp;
Ø Uniformity of size
Ø Good quality
Ø Physiologically developed;
Ø Absence of stalk;
Ø Clean;
Ø A pH ≤ 4.5; [13].
Transformation of fresh tomato into powder
To make tomato powder, we used a handmade wooden stove.
Description of the apparatus
The device is made of wood, powered by 220V-50Hz from the outlet, and has the following
dimensions: 13.2cm in length, 19.5cm in width, and 19.2cm in height. Its interior is coated with
aluminum paper, with an iron grid also coated with aluminum paper to avoid oxidation; it
contains two 75 Watts lamps, a 12 V fan, and two mercury thermometers.