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Influence of Home Freezing and Storage on Vitamin C Contents of Some Vegetables
Abstract
Okra, potatoes, green beans, broccoli, spinach and peas were included to determine the vitamin C levels of home freezing with the impact of processing and storage. Firstly, a preliminary study was done to find the high quality vegetables (in terms of Vitamin C) for freezing, then selected vegetables were prepared for freezing according to the appropriate nutritional principles and frozen. In the second phase, all frozen vegetables kept in the freezer (6 months) to evaluate the storage effects. Vitamin C analyses were conducted just after the pre-freezing operations that may cause Vitamin C destruction, freezing and storage (3. and 6. months). Spectrophotometric method (2,6-dichlorophenol indophenol) was used to determine the vitamin C levels. Depending on the vegetable type, pre-freezing operations caused 30.9-48.0% decrease in the initial vitamin contents. Home freezing alone did not make any significant difference, but 6 months of storage resulted a total of 42.4 (green beans) - 66.5 (broccoli) % decrease.
... L'écart-type n'a pas dépassé 0,43°C respectivement 0,37°C, donc un niveau acceptable. On peut conclure que la température moyenne du produit n'avait pas atteint la valeur prescrite de -18°C pendant le stockage et on estime que cela a conduit à des modifications de qualité pour le produit déposé [10,11] pendant 24 mois. ...
... On peut noter qu'après la congélation, le contenu en vitamine C est significativement plus élevé dans les échantillons de contrôle (98,23%), par rapport aux échantillons blanchis (72,01% (P1) et 63,59% (P4)). Le régime de blanchiment a influencé les pertes de vitamine C pendant les premiers 12 mois de stockage [8,10]. Pour les petits pois non blanchi la variation du contenu en vitamine C a été plus prononcée (Tableau 4). ...
... Après les 24 mois de stockage, par rapport au contenu initial en vitamine C, une concentration de 13,2% (échantillon contrôle) et de 30,5% (P3) ont été enregistrées, la moyenne étant de 23,2% (Figure 3). Ces résultats démontrent que l'opération de blanchiment a été efficace et a permis la préservation du contenu en vitamine C [10]. ...
The purpose of this study was to analyze the degree which fresh green peas maintain their technological properties and nutritional components during long-term storage, for a period of 24 months, in a defined condition of the air, at maximum -18°C. Peas were blanched, at four different durations of this operation and the same temperature of the blanching water, 95°C. The peas were frozen after end stored.
In conditions of long-term storage of frozen peas, it has been found a considerable loss of the initial content of vitamin C and damage of chlorophyll (total, a and b), under the action of chlorophyllase, causing some gray compounds.
The conditions of the storage in frozen stage produced a distortion of color and sensorial qualities, higher as the storage temperature was higher than prescribed. It was found that the best results in preserving quality of peas during long-term storage (24 months) were obtained for the blanched samples at 4 minutes at 95°C. The reducing of the content of vitamin C, chlorophyll a and b, and sensorial qualities was the lowest, overall.
... Contexte L'analyse quantitative du bénéfice nutritionnel le long de chaînes de production alimentaires est nettement moins développée que l'analyse quantitative du risque microbiologique. Néanmoins, il existe de nombreuses études sur les processus de dégradation des vitamines ou sur l'impact de certains procédés de fabrication comme le blanchiment ou la surgélation (Selman, 1994;Dewettinck et al., 2006;Sablani et al., 2006;Tosun and Yucecan, 2007), ainsi que des travaux de modélisation des pertes associées à certains traitements thermiques ou à de la diffusion (Arroqui et al., 2002;Corradini and Peleg, 2006;Leskova et al., 2006;Van Boekel, 2008;Pénicaud, 2009). Un objectif crucial de ces études est la recherche de procédés assurant la meilleure préservation possible des nutriments du produit. ...
... D'autres mesures existent dans la littérature. Une synthèse des différentes mesures, faites sur une dizaine de variétés de haricots verts, plusieurs lieux et plusieurs années, est présentée dans le Tableau 4.3(Tee et al., 1988;Selman, 1994;Favell, 1998;Oruña-Concha et al., 1998;Souci et al., 2000;Sanchez-Mata et al., 2003;Tosun et al., 2007) :Tableau 4.3. Concentrations en vitamines C dans des haricots verts frais. ...
The aim of this work is to set up microbiological risk and nutritional benefit assessment methods in the transformation of vegetables, in view of a risk-benefit analysis. The considered (industrial) risk is the alteration of green bean cans due to thermophilic bacteria Geobacillus stearothermophilus, and the nutritional benefit is the vitamin C content in appertized green beans. Reference parameters have first been acquired, by a meta-analysis using Bayesian inference for the risk part. Thermal resistance parameters D at 121.1°C and pH 7, zT and zpH of G.stearothermophilus have been respectively estimated at 3.3 min, 9.1°C and 4.3 pH units on average in aqueous media. The risk and benefit models have then been analyzed by a two-dimensional Monte Carlo simulation method, allowing a separated propagation of uncertainty and variability. The vitamin C losses between fresh and appertized green beans predicted by the model are of 86% on average, and the predicted non-stability at 55°C rate is of 0.5% on average, in good accordance with reality. A risk-benefit analysis has then been carried out to optimize benefit while keeping risk at an acceptable level, by exploring possible intervention scenarios based on some sensibility analysis results. Finally, a risk analysis model involving pathogenic bacteria Bacillus cereus in a courgette puree has been confronted to incubated product contamination data, by means of a Bayesian inference.
... Storage of classically frozen fruits for a long time can affect the content of bioactive compounds, certain organoleptic properties such as colour and antioxidant properties (Cordenunsi et al., 2005;Nursal Tosun and Yücecan, 2007). Chemical, biochemical, and physical reactions cannot be completely stopped during frozen fruit storage, so the rate of these reactions depends on storage temperature and time (Blando et al., 2004;Sahari et al., 2004). ...
Strawberry fruit species given an extremely high water content (90-92%) are prone to rapid spoilage and therefore it is difficult to preserve its fruits for a longer time period. An effective method to preserve strawberry fruits with significant preservation of nutritional and sensory quality is freezing. One of the methods increasingly in use, alternative to conventional freezing, is flash-freezing which implies significantly lower freezing temperatures (cryogenic) allowing freezing for just a few minutes. The aim of this study was to evaluate the effect of freezing method (conventional, flash-freezing) on the content of predominant specialized metabolites of strawberry fruit. Also, to determine the effect of storage period (10, 20 and 30 days) on the content of specialized metabolites. According to the obtained results, significantly higher values of vitamin C (5 times), total phenolic compounds (2 times), non-flavonoids (1.5 times), flavonoids (50%), total anthocyanins (3 times) and antioxidant capacity (2.7%) were determined in strawberry fruits frozen by flash-freezing compared to the conventional method. Also, as expected regardless of the freezing method, content of all analysed specialized metabolites significantly decreased during storage period. It should be emphasized that during storage, however, nutritional quality of flash-frozen samples was better preserved compared to the samples frozen by conventional method. Based on the stated, it can be concluded that flash-freezing significantly preserved the content of all analysed specialized metabolites in strawberry fruits, thus can be recommended as effective method for strawberry processing and storage.
... Methods of preparation of minimally processed fresh produce affect nutrient retention. Tosun and Yücecan (2007) studied vitamin C level and the factors affecting it before and during home processing and freezing and during freeze storage of some fresh vegetables including spinach. Vitamin C content of fresh spinach samples was 89.5 5.86 mg/100g. ...
... Thus, the need for much emphasis to be placed on fruits in the quest for optimal health benefits from plant-based diets. Moreover, fruits are usually eaten whole and raw and therefore do not require much processinga major factor in the loss of inherent beneficial constituents of most plant foods (Tosun and Yücecan, 2007;Kadar, 2002). ...
The surge in chronic diseases has necessitated the global call for increased consumption of diverse fruits and vegetables resulting in the need to study the potential health beneficial constituents of the underutilised. This research was aimed at assessing the dietary fibre fractions, proximate composition, antioxidant activity and phytochemical constituents of edible portions of four underutilised fruits viz., African mango (seeds and pulp), breadfruit (pulp), soursop (pulp) and sweetsop (pulp). Their total phenolic and ascorbic acid (vitamin C) contents were also determined. Samples for all determinations except proximate analysis were freeze-dried and stored: Some under refrigeration conditions for dietary fibre analysis, and the rest at - 20 oC. Proximate and phytochemical analysis was done by standard methods. The antioxidant activity and phenolics were determined by spectroscopy using 2, 2-diphenyl-1-picrylhydrazyl radical scavenging and the Folin-Ciocalteu protocol, respectively. The ascorbic acid content was determined by titrimetry and an enzymatic-gravimetric method employed for the dietary fibre determinations. Proximate values (% mean) ranged from 2.63±0.11 to 6.71±0.07; 2.44±0.07 to 4.00±0.03 and 2.60±0.41 to 13.90±0.58 for protein, ash and fat respectively. Generally, tannins, triterpenoids, saponins, sterols, cardiac glycosides, flavanoids and coumarins were detected. Antioxidant activity of the samples ranged from 63% (breadfruit) to 78% (African mango pulp) and the highest phenolic content was recorded in African mango seeds. Total dietary fibre contents ranged from 11.50 (soursop) to 22.70 (African mango pulp) g/100g while ascorbic acid contents of the fruit mesocarps ranged from 20.32 (sweetsop) to 62.52 (soursop) mg/100g. There were non-significant correlations (P < 0.05) between the phenolics, ascorbic acid contents and antioxidant activities. The study suggests significant composition of health beneficial constituents - dietary fibre, vitamin C and presence of an array of phytochemicals - as well as fairly high antioxidant activities of the stated fruits. Thus, the need to exploit them in seeking optimum health of the populace.
... The distributions of C INIT vit C and prop AA have been established from literature, unpublished data and assays performed in the present work on several green bean cultivars grown in diverse locations worldwide (Favell, 1998;Oruña-Concha, Gonzalez-Castro, Lopez-Hernandez, & Simal-Lozano, 1998;Sanchez-Mata, Camara, & Diez-Marques, 2003;Selman, 1994;Souci, Fachmann, & Kraut, 2000;Tee, Young, Ho, & Mizura, 1988;Tosun & Yucecan, 2007). There is no evidence of prop AA variations in fresh green beans. ...
الملخص
اجريت هذه الدراسة في الفترة الواقعة بين شهري كانون الثاني ينابر/ وشهر شباط / فبراير لمعرفة تاثير طرق السلق المختلفة ( الغمر بالماء المغلي T1 والبخارT2 والمايكروويف T3) لمدة 5 دقائق على فعالية انزيم البيروكسيديز والخصائص النوعية لشرائح الجزر المخزنة بالتجميد لفترة 30 يوم. تم قياس فعالية انزيم البيروكسيديز لجميع المعاملات واجراء بعض الاختبارات الكيميائية والحسية لشرائح الجزر قبل وبعد التجميد. اظهرت النتائج وجود فروقات معنوية عند مستوى احتمالي (P<0.05) بين المعاملات T3, T2, T1 مقارنة مع معاملة السيطرة T0(جزر غير المسلوق) اذ انخفضت فعالية الانزيم تدريجيا مع تقدم مدة الخزن. ويلاحظ من النتائج ان وقت السلق كان غير كافي لوقف نشاط الانزيم والذي يعتبر دليل على كفاءة عملية السلق, في حين ازدادت نسبة الرطوبة والرقم الهيدروجيني بينما انخفضت نسبة المادة الجافة ونسبة الحموضة الكلية ومحتوى حامض الاسكوربيك للمعاملات T3, T2, T1 مقارنة مع (معاملة السيطرة ) T0. وبينت نتائج الاختبارات الحسية عدم وجود فروقات معنوية عند مستوى احتمالي (P<0.05) بين المعاملات T3, T2, T1 مقارنة مع ( معاملة السيطرة) T0 وكانت افضل معاملة هي طريقة السلق بالماء المغلي والسلق بالمايكروويف من حيث اللون والقوام في حين لم يظهر اختلاف بالطعم والرائحة لجميع المعاملات بعد انتهاء فترة الخزن بالتجميد.
The effect of nitrogen (N), sulfur (S), and zinc (Zn) fertilization on the yield quantity and selected qualitative parameters of broccoli was studied in an experiment carried out in Nitra (Slovak Republic) during 2011 and 2012. In this experiment, the following fertilization treatments were tested: control; N200S80 (fertilized to the supply level: 200 kg N ha-1 and 80 kg S ha-1); N200S100 (supply level: 200 kg N ha-1 and 100 kg S ha-1), and N200S100 Zn (supply level: 200 kg N ha-1 and 100 kg S ha-1 + foliar zinc application). Compared to the control treatment, higher broccoli yield was shown at all fertilized treatments. The most significant increase in yield quantity was found at N200S100Zn, i.e. about 59% higher than the control. Application of N200S100Zn was the most suitable fertilization from the standpoint of broccoli quality. The foliar Zn spraying led to a statistically highly significant increase of sulforaphane in broccoli (about 41.1%) compared to the control. The applied N and S fertilization tended to decrease the vitamin C content in broccoli (about 9.2%) against the control. On the other hand, Zn application resulted in a return of the vitamin C content, nearly to its level in control. The results confirmed the well-known fact that nitrogen fertilization leads to nitrate accumulation in vegetables. However, the results of this research indicate that nitrogen fertilization combined with zinc application should be expressed mainly by lower nitrate accumulation in the edible parts of broccoli. The experimental data are interesting, and in terms of growing vegetables for consumption with enhanced quality, promising. This is notable because the formation of many serious diseases is increasing.
Changes in vitamin C concentration along the processing chain of canned green beans were predicted with a probabilistic and modular process model using vitamin C concentrations in raw green beans, constants of chemical reactions (activation energy, reaction rates and diffusivity) and process descriptors (time and temperature, dissolved oxygen concentration). The model accounts for the statistical uncertainty and/or variability of these quantities. The initial vitamin C concentration in green beans, partly established with n = 65 proper vitamin C assays, was (mean [variability interval at 95 %]) 17 mg vitamin. 100 g-1 [4.1, 30.3] and markedly decreased to 7.5 mg. 100 g-1 [0.6, 14.9] after blanching, to 6.2 mg. 100 g-1 [0.3, 12.5] after sterilization, and to 2.3 mg. 100 g-1 [0, 5.6] after storage. The model predictions were globally on agreement with independent observations that include specific vitamins C assays (n = 26) at different steps of processing.
This research aimed at investigating the effect of preliminary treatments of fresh Artichoke (blanching period, salting, adding acid), on quality parameters of canned and frozen Artichoke before and over a six months period of preserving. In addition, the research tested the efficiency of the applied blanching process was by exploring the presence of enzymes that causes Enzymatic browning. The results showed the freezing method was more preserving to Artichoke’s parameters, in comparison with the canned artichoke. Preserving Artichoke for six months resulted in significant reduction of its biochemical content. Blanching resulted in eliminating the enzymes caused Artichoke's coloring and browning. Furthermore, the results revealed that blanching period of 10-20 minutes had contributed to increasing the level of effective biological components. Adding Acid (2%) and the Calcium chloride salt (1-2%) resulted in significant increase in quality parameters for canned and frozen artichoke, compared to the control (which just preserved without any applied processes). © 2015. International Journal of ChemTech Research. All rights reserved.
The reduced ascorbic acid and β-carotene contents of “retail market-fresh” (RMF) and “fresh-frozen” (FF) green beans and broccoli in a simulated handling system were determined. Changes in ascorbic acid content in the two vegetables during a retail market period and frozen storage followed different patterns. In green beans, ascorbic acid content decreased during refrigerated storage for up to 7 days, but in broccoli there was a significant increase. Blanching resulted in a loss of approximately 40% of the ascorbic acid in broccoli. Ascorbic acid content of FF green beans stored at-20C for 16 weeks was approximately twice that in RMF green beans, but in FF broccoli stored under the same conditions it was only about half that of RMF broccoli. β-carotene content of green beans and broccoli did not change during either the retail market simulation of frozen storage and did not differ from that of fresh.