Review Article Journal of Advanced Research in Food Science and Nutrition (ISSN 2582 3892) Copyright (c) 2021 Advanced Research Publications Journal of Advanced Research in Food Science and Nutrition[.]
Trang 1Review Article
Peer Reviewed Journal
The main purpose of this study to improve the product quality of dried Queen Pineapple, a new strategy utilizing ultrasound pretreatment combined with cold air drying This research was conducted on pineapple fruits (pineapple Queen Long Thanh, Dong Nai) with high sugar content of about 16-18 °brix, especially vitamin C, the highest rate was 47.8mg/100g Determining the appropriate ripeness is maturity
of pineapple fruit with maturity of about 10 - 20% of the surface of pineapple skin with yellowish green color, with this ripeness, the product will give best quality For the study, we examined pineapple slices with 3mm,5mm, 7mm were first pretreatment with ultrasonic for 30 minutes, subjected to osmotic dehydration process using sugar syrup of 20 °Brix,
25 °Brix and 30 °Brix for 3 hours at room temperature Pineapple slices were drying at 5 °C about 1800 minutes until moisture content was 14
± 0.1% When comparing the quality of two methods of conventional drying and cold air drying, the method of cold air drying food is the best method of drying food to retain vitamin C, which is the most easily lost during the drying process, but the cold air drying method still preserve very high content of vitamin C, for dried pineapple products is 30 mg/ 100g and improve the color of the final product
Keywords:Pineapple fruit, Cold air drying, Ultrasonic, Osmotic
Corresponding Author:
Nguyen Thi Ngan, Faculty of Health Sciences
and Finance - Accounting, Dong Nai Technology
University, Dong Nai, Vietnam
E-mail Id:
nguyenthingan@dntu.edu.vn
Orcid Id:
https://orcid.org/0000-0001-6416-2568
How to cite this article:
Ngan NT, Luan NT, Khanh TV et al Quality
Characteristics of Dried Queen Pineapple by
Cold Air Drying Combined with Ultrasound
Pretreatment Process J Adv Res Food Sci Nutr
2021; 4(1): 10-14
Date of Submission: 2021-04-14
Date of Acceptance: 2021-05-30
Quality Characteristics of Dried Queen
Pineapple by Cold Air Drying Combined with Ultrasound Pretreatment Process
Nguyen Thi Ngan1, Nguyen Thanh Luan2, Tran Van Khanh3, Nguyen Quoc Cuong4
1,2,3Faculty of Health Sciences and Finance - Accounting, Dong Nai Technology University, Dong Nai, Vietnam
4Faculty of Technology, Dong Nai Technology University, Dong Nai, Viet Nam
Introduction
Fruits and vegetables are a good source of important
essential nutrients such as vitamins, minerals and fiber
In Vietnam, the pineapple varieties are currently grown
in Ananas comosus species This species is divided into
7 groups including 3 main groups: Cayen, Queen and
Spanish pineapple Pineapple is one of the most important
commercial fruit crops with several health benefits.10 It is
low in fat and cholesterol Pineapple is also a good source
of vitamin B1, vitamin B6, copper and dietary fiber.7 Using
pineapple could help to increase the immune system, aids
digestion of proteins, reduce symptoms of the common cold and strengthens bones.14 Pineapple makes up a large amount of water (more than 80%), and so it is classified as perishable Many different products can be processed from pineapple like juices, squash, wines, jams, concentrates and powder.13
Drying is the most common method of food preservation Conventional air-drying is a simultaneous heat and mass transfer process, accompanied by phase change.2 Traditional drying methods often use high temperatures to dry out a lot of water, but with the cold air drying method combined
Trang 2with ultrasonic permeation, the product will reduce loss of
color, loss of nutrients, and structure With the purpose to
effective conservation of nutrients, color, cold air drying is
known for its low temperature and humidity Barbosa AF
et al found that cold air drying could better preserve the
product’s nutrients comparing with hot air drying.3
The pretreatment ultrasound process affects the energy of
the drying process as well as the sugar content in the final
product because according to Fernandes et al pretreatment
ultrasound reduces sugar content by 21-52% but does not
affect drying time.8 The ultrasonic pre-treatment involves
the immersion of the fruit in water or in a hypertonic
aqueous solution to which ultrasound is applied The
advantage of using ultrasound is that the process can
be carried out at ambient temperature and no heating is
required, reducing the probability of food degradation.9
Studies on drying of fruits and vegetables have carried out
ultrasound to assist osmotic dehydration15-17 and there have
been many studies published involve with the implement
of ultrasound on drying.19-21
However, there have not been many studies conducted on
cold air drying combined with osmotic ultrasound, which
has been successfully used in reducing moisture content
to 14 ± 0.1% and maintaining the original product quality
Material and Method
Materials and Equipment
Pineapples are bought at the garden house in Long Thanh
Dong Nai, Vietnam
Equipment
Methods
The color and browning index measurement can be found
in the literatures.11 Color was determined based on the CIELab system, a colorimeter (Colori5, USA) was used for dried pineapple slices immediately after drying The color values of the samples were expressed as L* (whiteness/ darkness), a* (redness/greenness), and b* (yellowness/ blueness) Total color difference (ΔE) was estimated by:
Where Lo*, are represent the color values of the fresh pineapple slices samples, and L*, a*, and b* represent the color values of dried samples Five selected samples were repeated three times in each group
Moisture content was estimated in the samples using A.O.A.C method.1 Five g of sample was weighed and transferred to pre-dried dish Weighed sample was dried
in hot air oven at 105 °C The dish with dried sample was transferred to desiccators, cooled to room temperature and weighed
The ascorbic acid determination was performed by the titrimetric method based on the reduction of the indicator
2, 6-dichlorophenolindophenol by the ascorbic acid as described in A.O.A.C.1
Statistical Analysis
All analysis were performed in triplicate Statistical analysis were using statistical software Stargraphic 5.0
Prepare Material
Pineapple selected materials and collect purchased at the garden of the same maturity (left two yellow eyes from the bottom of the left) Pineapples were left to ripen under normal laboratory conditions before being used for experiments
After that, the pineapple was removed at both ends, only the middle part of the pineapple was used for the experiment, when the concentration of dissolved dry matter
Figure 1.Comparative status of agricultural sector to
the overall economic growth of Nepal
Table 1
Power Consumption (KW/h) 3.7kW/24h
Trang 3ranged from 13-18 °Brix Next, the pineapple was peeled,
gently cut into slices of different thicknesses, gently wipe
the surface of the pin with dry tissue to prepare for the
experiment and mixed with syrup solution in Ultrasonic
Machine in period time and drying in equipment at 5°C at
wind speed 2 m/s
Result and Discussion
Investigate the Influence of Ripeness on Product
Quality after Drying
Figure 2.Picture of product after drying
Figure 3.Picture of product after drying
Figure 4.Drying curve of affecting brix of solution on
drying time
Table 2.Color measurement results
In Table 3 shows that three samples dried at the same
period temperature, the moisture content of each sample
is not significantly different, but we can see at the ripeness
of sample 2 (ripeness 2) drying times to achieve a constant
moisture content than the rest of the sample about 6 hours
In ripeness 2 about the color, we can also see in the table
that it is clear that the color ratio is not too different, but
the ripeness 2 has a higher score of ∆ * L and ∆ * b, showing
the brightness and golden ratio of the sample Higher than
the rest of the samples, proving that ripeness 2 has the
same color as the fresh pineapple The drying time of the
ripeness 2 was the lowest according to Table 3 after only 18
hours reaching 14% moisture So we have decided ripeness
2 is optimal for inclusion in the experiments to follow
Surveying material thickness: slice of pineapple 3 mm, 5
mm and 7 mm
In Figure 3, we could see that the moisture loss of the material over each drying time of 3 samples, with samples
1 and 2 here having reached the optimum moisture content within 24 hours Particularly for sample 3 (7 mm) because the size is thicker than other samples, the drying process will take longer to achieve results than the other samples In terms of the panel parameters and sensory assessments, we
can see that with 5mm size the sensory requirements and the most drying time as this sample product showed great beauty and moisture content request As for the number
1 sample (3 mm), we did not choose because the sensory evaluation committee commented that this sample is too thin, the shape is not good shape Therefore, in order to achieve the best results and the most beautiful product in terms of the most sensory value for the next experiments,
we decided to use the 2nd model of size 5 mm with 1680 minutes to have the moisture content 14%
Investigate the Effect of Osmotic Solution
In Figure 4, we observe the graph of drying curve of 3 concentrations We found that the concentration of 20 °Brix and 25 °Brix had quite similar drying speed, however, the concentration of Brix 20 achieved the required moisture content faster during the experimental observation period Regarding the concentration of 30 °Brix, we see that the drying speed is quite fast and it only takes 24 hours to reach the optimum moisture However, in terms of organoleptic
Trang 4aspects, the Brix 30 concentration was too sweet compared
to the other two samples, because the tastes of today’s
consumers do not like to eat too sweet, we decided to
achieve moisture Optimize and keep consumer needs,
we choose 25 °Brix concentration to perform experiments
Compare the Quality of Dried Pineapple between
Traditional Drying 60 °C and Cold Air Drying 5 °C
Observe physicochemical indicators in Table 4 we can see that the ∆*L index of the dark to light color index and the
∆ *b index of green to yellow color of cold method have higher brightness and yellow color than that of thermal drying method This tells us that the method of cold drying retains pineapple’s color better than the method of heat drying In Figure 5 and 6, we can see that the moisture loss in the two drying methods has a significant difference With the same pretreatment method, the traditional drying method achieved the required moisture content in 16 hours compared to the 24-hour cold air drying method For the traditional drying method, the outstanding advantage
is that the drying time is shorter than that of the cold drying method, but the color of the final product no longer preserves the color of the pineapple as well as vitamin C content is lower than As for the cold air drying method
as we all see the advantage of this method is to retain the color of fresh pineapple with the best sensory value, and vitamin C content is higher than
Conclusion
The results of the study showed that the appropriate ripeness is the second maturity of pineapple with maturity
of about 10 - 20% of the surface of pineapple skin with yellowish green color, light yellow flesh With this ripeness, the product will give good quality, the optimal size for the survey is 5 mm, the best osmotic concentration for the product is 25° Brix, the ultrasonic time of 30 minutes, temperature drying is 5°C will give the product time to dry The best quality is compared to the two methods of cold and heat drying The dried pineapple-based product still retains very high levels of vitamin C, for the dried pineapple product is 30 mg/100 g
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