Pineapple powder production PDF

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INTRODUCTION Pineapple Pineapple (Ananas comosus) is a tropical fruit which may be enjoyed whole and fresh, juiced or canned. It is believed to have originated in Southern Brazil and Paraguay and spread throughout the continent by native populations (Duval et al., 2003).The fruit is now of high economic importance due to its export value contributing to over 20% of the world production of tropical fruits (Coveca, 2002). Thailand, Philippines, Brazil and China are the main pineapple producers in the world supplying nearly 50% of the total output (FAO, 2004). Today, the world pineapple trade is dominated by four multinational agribusinesses; Dole Food Company, Del Monte Foods, Fyffes and Chiquita. Pineapples are generally exported as the canned-fruit, concentrated juice and dried pineapple slices. Although there are a number of pineapple products in the market, the food industry still keeps developing new product from pineapple. The benefits of constantly developing a product are the elevation of the fresh pineapple demand and consequently reducing the pineapple loss caused by the microorganisms, chemical and enzymatic reactions during the peak of harvesting season (Nicoleti et al., 2001; Gabas et al., 2007). Pineapple powder is an interesting product because of its long shelf life at ambient temperature, convenience to use and low transportation expenditure. Pineapple powder can be consumed as an instant juice powder or a flavouring agent. So far, there have been merely few studies about the production of pineapple powder. Some researchers claimed that drying of fruit juice could produce the fruit powder that reconstituted rapidly to a fine product resembling the original juice (Gabas et al., 2007). Nonetheless, there are some difficulties in drying the fruit juice with high sugar content like pineapple due to their thermo-plasticity and hygroscopicity at high temperatures and humidities causing their packaging and utilization in trouble (Adhikari et al., 2004). Spray drying is a technique widely used in the food industry to produce food powder due to its effectiveness under the optimum condition (CanoChauca et al., 2005). Due to the lack of research about oven-dried pineapple powder

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from juice and puree, this preliminary study was carried out with the following objectives; (1) to study the feasibility of producing the oven-dried pineapple powders from fruit juice and puree and (2) to determine the pysico-chemical attributes of the oven dried pineapple powders.

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REVIEW OF RELATED LITERATURE Local Pineapple Production Pineapple is now the third most important tropical fruit in world production after banana and citrus. Major pineapple procducts of international trade are canned slices, chunks, crush (solid pack) and juice and fresh fruit (Fig. 1-1). The country’s pineapple production in January-March 2013 was 541,855 mt. This was 5.82 percent higher than the previous year’s level of 512,050 mt. The upward trend in pineapple production was attributed to the following: there is an increase in planting density in Davao Region; production of bigger fruit sizes and more areas harvested in SOCCSKSARGEN; the effects of fertilizer application in Bicol Region; and shift of more areas devoted to pineapple from coffee in CALABARZON. Pineapple production in Northern Mindanao at 275,565 mt had a 50.86 percent share in the country’s production. The region recorded a 9.88 percent increment over last year’s production.

Figure 10-1. Different products and cuts derived from pineapple.

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Challenges in Spray Drying Method Drying of fruit juice with high sugar content like pineapple is said to be difficult due to their thermo-plasticity and hygroscopicity at high temperatures and humidities (Adhikari et al., 2004). These characteristics are attributed to low molecular weight sugars such as fructose, glucose and sucrose and organic acids such as citric, malic and tartaric that are the major solids in fruit juices (Bhandari et al., 1997). The low glass transition temperature (Tg), high hydroscopy, low melting point, and high water solubility of these solids lead to a highly sticky product when spray dried (Adhikari et al., 2003). These solids normally have low glass transition temperatures. Additionally, Roos and Karel (1991) stated that these materials are very hygroscopic in amorphous state and loose free flowing character at high moisture content. The thermoplasticity and hygroscopicity problems occurring in drying the fruit juice with high sugar content can be overcome by adding some carriers such as maltodextrin (MD) and Arabic gum (Cano-Chauca et al., 2005). The drying carriers or adjuncts are high molecular weight compounds that have high Tg; as a result, they can raise the Tg value of feed and the subsequent powder (Shrestha et al., 2007). According to Cano-Chauca et al. (2005), MD is a carrier which is the most popular in spray drying due to its physical properties such as high water solubility. Gabas et al. (2007) described that MD consists of b-D-glucose units linked mainly by glycosidic bonds and are typically classified by their dextrose equivalent (DE). Bhandari et al. (1997) and Silva et al. (2006) pointed out that MD could improve the stability of fruit powder with high sugar content because it reduced stickiness and agglomeration problems during storage. Also, Shrestha et al .(2007) indicated that the increasing amount of MD could increase the product recovery and the lightness of the orange juice powder.

Moisture Sorption Isotherm Brunauer et al. (1940) classified sorption isotherms according to their shape and processes, establishing five different types; as it is shown in Figure 10-2. Type 1: Langmuir and/or similar isotherms that present a characteristic increase in water activity related to the increasing moisture content; the first derivative of this plot

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increases with moisture content and the curves are convex upwards. This type of sorption isotherm is typically applicable in the process of filling the water monomolecular layer at the internal surface of a material. Type 2: sigmoidal sorption isotherms, in which the curves are concave upwards; it takes into account the existence of multilayers at the internal surface of a material. Type 3: known as the Flory-Huggins isotherm, it accounts for a solvent or plasticizer such as glycerol above the glass transition temperature. Type 4: it describes the adsorption of a swellable hydrophilic solid until a maximum of site hydration is reached. Type 5: the Brunauer-EmmettTeller (BET) multilayer adsorption isotherm, it is the one observed in the adsorption of water vapour on charcoal and it is related to the isotherms type 2 and 3. The two isotherms most frequently found in food products are the types 2 and 4 (Blahovec and Yanniotis, 2009; Basu et al., 2006; Mathlouthi and Roge, 2003). .

Figure 10-2. Types of isotherms described by Brunauer (Mathlouthi & Rogé, 2003).

Nutritional Composition Pineapple composition has been investigated mainly in the edible portion. Reported ranges of the main components from data collected from several commercial

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operations and include additional variables as environmental factors and degree of maturity of the fruit. Pineapples contain 81.2 to 86.2% moisture, and 13-19% total solids, of which sucrose, glucose and fructose are the main components. Carbohydrates represent up to 85% of total solids whereas fiber makes up for 2-3%. Of the organic acids, citric acid is the most abundant. The pulp has very low ash content, nitrogenous compounds and lipids (0.1%). From 25-30% of nitrogenous compounds are true protein. Out of this proportion, ca. 80% has proteolytic activity due to a protease known as Bromelin (Dull, 1971). Among the different medicinal and healing properties of pineapples it has been said that the fruit is antiparasitic, abortive, detoxifier, vermifuge and stomach disorder relief. Pineapple also improves digestion, regulates stomach acidity, aids in detoxification processes, the neutralization of free radicals and blood clots, as aid in the treatment of rheumatoid arthritis, reduction of sciatica symptoms, collagen production, weight control and in the treatment of albuminuria. Evidence of these claims was generated from studies made in the US and Europe (Coveca, 2002). One of the best known properties of pineapple is as a diuretic. This helps to eliminate toxins through the urine, helping patients with ailments of kidneys, bladder and prostate. Due to the fiber content of the pulp, pineapple prevents constipation and regularizes the intestinal flora. Furthermore, there is evidence of appetite reducer, heart protection and aid for fever, sore throat and mouth aches and inflammation. Lightly boiled ground pineapple can be used to clean infected wounds because it eliminates dead tissues, not affecting live tissue, acts as disinfectant and accelerates cicatrization (Mundogar, 2004).

Methodology Materials

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Fresh, mature and ripe pineapples were purchased from local market. Pineapples with average weight were chosen for the experiment. The maltodextrin (M20) and sugar was also purchased from the local market.

Preparation of Pineapple Puree Fresh pineapples were washed thoroughly to remove adhering dirt, then peeled off and cut into cubes. The cubes were homogenized using laboratory electrical blender. Four portions of the puree were set aside. The following preparations are done on the formulation of oven dried pineapple powder. Treatment 1: this formulation consisted of pineapple puree, sugar and maltodextrin with 60:20:20 ratio. Pineapple puree was heated at 80°C with constant stirring. Then sugar and maltodextrin were added and adjusted the weight to one (1) kg. The mixture was then poured in trays with plastic sheet. It was loaded and dried in the drier until sample become crisp. The temperature of the oven was set at 55 °C. Treatment 2: the same procedure with Treatment 1 was carried out but the formulation is different. This formulation consisted of pineapple puree and maltodextrin with 60:40 ratio. Treatment 3: this formulation consisted of pineapple juice, sugar and maltodextrin with 90:30:30 ratio. Pineapple puree was filtered to extract the juice. Then, the juice was heated at 80°C for five (5) minutes with constant stirring. Sugar and maltodextrin were added and adjusted the weight to one (1) kg. The mixture was then poured in trays with plastic sheet. It was loaded and dried in the drier until sample become crisp. The temperature of the oven was set at 55 °C. Treatment 4: the same procedure with Treatment 3 was followed but the formulation is different. This formulation consisted of pineapple juice and maltodextrin with 90:60 ratio.

Quality Determination

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The soluble solid content and pH of the pineapple puree, juice and mixtures produced in Treatments 1, 2, 3 and 4 were measured by hand refractometer and pH meter respectively.

Physical Analysis of the Oven-dried Powder The oven-dried powders were analyzed for their moisture content and moisture sorption isotherm. Moisture content The moisture content was determined based on AOAC method. In brief, each samples of pineapple powder (2g each) were weighed and then dried in an oven at 100°C to 105°C for 7 hours. The samples were taken out from the oven, cooled in a desiccator and weighed. Moisture sorption isotherm Two hundred ml of saturated solutions of each salt was carefully place in separate jars and closed tightly. These were allowed to stand for 24 to 48 hours to equilibrate. Dry crucibles were loaded in MSI jars (see Table 10-1). Set-up was equilibrated for one (1) week. Moisture content of samples was determined before loading in MSI jars. This data was used in calculating equilibrium moisture content. About 2 grams of oven-dried pineapple powder were placed in a tared crucible. These were exposed to different relative humidity inside the glass jars. Loss or gain in weight of the samples was periodically determined until equilibration was attained. The moisture content at this point is the equilibrium moisture content (EMC), which was determined using a relative humidity (%RH) in the glass jars where samples were stored was plotted A smooth curve was drawn and this was the sorption isotherm of the powder.

Table 10-1. Determination of the moisture sorption isotherm (Weight equilibrium method)

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RH% 11 23 32 42 52 62 75 79 89

Results and Discussion

Saturated salt solution Lithium chloride Potassium acetate Magnesium chloride Potassium carbonate Magnesium nitrate Cobalt (II) chloride Sodium chloride Ammonium sulphate Barium chloride

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Quality of Raw Material The measurement of soluble solid content, colour and pH of the fresh pineapple puree and juices revealed that their soluble solid contents ranged 11-12°Brix. The average of pH of the fresh pineapple puree and juices in this study was 4.6. Listed in Table 10-2 are the soluble content and pH of the different formulations in making pineapple powder. Table10-2. The soluble solid content and pH of the mixtures produced in Treatments 1, 2, 3 and 4. Parameter Treatment pH TSS, °Brix 1 (puree+sugar+MD) 4.6 47 2(puree+MD) 4.6 12 3(juice+sugar+MD) 4.5 44 4(juice+MD) 4.5 12

Pineapple Powder Appearance The preliminary experiments implied that addition of 20% sugar and 20% maltodextrin in pineapple puree and juice in treatments 1 and 3 respectively resulted to sticky products. The big challenge in spray drying of fruit juice with high sugar content like pineapple is their thermo-plasticity and hygroscopicity at high temperatures and humidities (Adhikari et al., 2004). These characteristics are attributed to low molecular weight sugars such as fructose, glucose and sucrose and organic acids such as citric, malic and tartaric that are the major solids in fruit juices (Bhandari et al., 1997). The low glass transition temperature (Tg), high hydroscopy, low melting point, and high water solubility of these solids lead to a highly sticky product when spray dried (Adhikari et al., 2003). The thermoplasticity and hygroscopicity problems occurring in drying the fruit juice with high sugar content can be overcome by adding some carriers such as maltodextrin (MD) and Arabic gum (Cano-Chauca et al., 2005). But in this experiment, the sugar and maltodexrin combination did not work. Hence, drying of treatments 1 and 3 was discontinued and it was re-processed to pineapple fruit roll instead.

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On the other hand, in treatment 2 (pineapple puree + MD) and 4 (pineapple juice + MD), the appearance of the pineapple powder product were light yellow and powdery with high intensity of pineapple aroma. The samples were dried for almost 48 hours at 55°C. This is a very long process compared with spray drying technique.

Moisture Content and Powder Recovery The outcomes of moisture content and powder recovery determinations for the pineapple powders are presented in Table 10-3. The results showed that the moisture contents of the powders were 9.2 and 10.0 for T2 and T4 respectively. This is higher compared with the reported value of Jittanit (2010) in the range of 4.0-5.8%. Moisture content represents the water composition in a food system. The values in Table 10-3 indicate that spray drying provided high powder recovery of 81.3 % and less powder recovery in all oven dried powder. More studies are needed to prove the efficiency of oven drying method in the production of pineapple powder. Table 10-3. The moisture contents, solubility and powder recovery of the pineapple powders. Parameters Formulation Moisture Powder Solubility Reference (minute) Content (%) Recovery (%) *Jittanit Pineapple juice 5.2 81.3 4.4 +20% MD (2010) T2:Pineapple 9.2 55 No data **This study puree + 20% MD T4:Pineapple 10.0 44 No data **This study juice + 20% MD *spray dried (drying temperature: 150°C; feed rate: 0.022 (1pm)) **oven dried (drying temperature: 55°C)

Moisture Sorption Isotherms of Oven-dried Pineapple Powder The food sorption isotherm describes the thermodynamic relationship between water activity and the equilibrium of the moisture content of a food product at

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constant temperature and pressure. The knowledge and understanding of sorption isotherms is highly important in food science and technology for the design and optimization of drying equipment, design of packages, predictions of quality, stability, shelf-life and for calculating moisture changes that may occur during storage. Several preservation processes have been developed in order to prolong the shelf-life of food products by lowering the availability of water to microorganisms and inhibiting some chemical reactions (Al-Muhtaseb et al., 2004; Arslan and Togrul, 2005; Durakova and Menkov, 2005; Yan et al., 2008). The average equilibrium moisture content (EMC) of the different treatments of the oven-dried pineapple powder at different relative humidity is shown in Table 10-4. Based on the experimental computed values, the EMC of all the samples generally increase as the relative humidity also increased. Table 10-4. Equilibrium moisture content (EMC) of oven-dried pineapple powder at different RH, % EMC, % Treatment 2 4 11 2.44 2.38 23 4.91 4.54 32 5.83 5.31 42 8.17 7.65 52 8.21 11.20 62 11.92 12.20 75 18.30 17.51 79 21.49 39.24 89 35.60 36.07 The increase in EMC of the samples is may be brought about by the vapour pressure deficit (VPD) which decreases as relative humidity forms an atmosphere near saturation and enhances the capability of the material to absorb more moisture from the surrounding atmosphere. Thus, equilibrium moisture content increases with increasing relative humidity at the same temperature (Mostafa and Sourell, 2009). Table 10-5. Number of days for the oven-dried pineapple powder to reach equilibrium moisture content (EMC) and their physical appearance at

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different relative humidities. RH, % Treatment 2 4 11 10/light yellow/powdery 10/light yellow/powdery 23 17/light yellow/powdery 17/light yellow/powdery 32 17/light yellow/caking 17/light yellow/caking 42 17/light yellow/caking 17/light yellow/caking 52 17/light yellow/caking 17/light yellow/caking 62 17/light yellow/caking 17/light yellow/caking 75 17/light yellow/caking 17/light yellow/caking 17/light yellow with 17/light yellow with 79 browning/caking browning/caking 89 17/moldy/caking 17/moldy/caking Table 10-5 indicates the physical appearance of the oven-dried pineapple powder and the number of days it took to equilibrate the samples in the glass jars with varying relative humidities. Changes in physical state of the powders were observed at different relative humidities. Both treatments have light yellow coloured powder from 11% down to 75% RH. Browning and growth of molds were observed at 79% and 89% RH respectively. Caking of the samples was also observed. Mathlouthi and Roge (2003) defined caking as the lumping of food powders due to spontaneous agglomeration phenomenon as a result of liquid bridges formation. It happens in surfaces containing amorphous products due to surface plasticization induced by water sorption. Caking frequently occurs in water soluble powders which are exposed to high relative humidity.

The

succeeding

moisture

evaporation

causes

recrystallization,

agglomeration and the deposition of solid bridges between particles. Figure 10-3 illustrates the equilibrium moisture content of the two formulations of oven-dried pineapple powder where EMC was plotted against different relative humidities. The curve obtained in this study for both treatments 2 and 4 exhibited Type 2 sigmoidal sorption isotherm. Three major factors, including colligative solution effects, capillary effects, and surface interaction, occur over the whole moisture range in biological systems and yield the characteristic sigmoidal sorption isotherm (BarbosaCanovas et al., 2007).