MINISTRY OF EDUCATION AND TRAINING NONG LAM UNIVERSITY - HO CHI MINH CITYFaculty of Chemical Engineering and Food Science Technology IMPACT OF TEMPERATURE AND RELATIVE HUMIDITY ON PHYSIC
Overview of cashew kerneÌS - - << St xnxx TH TT TT HH HH rệt 3
Origin, history and distrIDufIOH . c5 2E *2E 3 E£EEEErrkrrrerrkrrrerrrree 3 2.1.2 Characteristics of cashew kerneÌS . - + + sxsxsstrrrrrrrrrrrrrrrree 3
The cashew (Anacardium occidentale L.), part of the Anacardiaceae family, is native to North-Eastern Brazil and thrives in various South American countries Introduced to Africa by the Portuguese in the 16th century, it gained popularity and cultivation in tropical Asian regions Originally planted for erosion control, the cashew tree's economic potential led to its widespread cultivation as an important industrial crop.
In Vietnam, the cashew tree, known as the upside-down fruit tree, was introduced in the 18th century but only became a commercial crop in the 1990s with the growth of the cashew processing industry Cashew trees thrive in regions such as Southeast Vietnam, the Central Highlands, and South-Central areas, including Binh Phuoc, Dong Nai, and Binh Thuan Today, Vietnam stands as the world's largest exporter of cashew kernels and ranks third in global cashew production, following India and Ivory Coast.
The cashew was a long-lived industrial tree with a lifespan of up to 40 years, usually providing stable yields during the period from 10 to 20 years after planting (Pham et al.,
The cashew fruit consists of two distinct components: the pear-shaped, aromatic fleshy part and the seed nut, or kernel, which is located beneath the fruit and encased in two hard shells.
Figure 2.1 Cashew apple (Anacardium occidentale L)
(Source : https://nongnghiepso.com.vn/)
Vietnamese cashew kernels are characterized by their smaller, kidney-shaped form with a slightly swollen stem and a tapered end They feature a round, taut body, a dark brown silk shell, and a smooth, appealing light-yellow kernel In contrast, imported cashew kernels are larger, more rounded, and have a light brown silk shell with noticeable wrinkles When broken, imported cashews reveal a deep groove and a hollow, milky white kernel (Dang, 2019).
Nutritional composition of cashew kernels and their health benefits
Cashew kernels are gaining popularity in food processing due to their rich nutritional profile and health benefits They contain monounsaturated fats that enhance cardiovascular health and lower triglyceride levels Furthermore, the unsaturated fats in cashew kernels facilitate the absorption of fat-soluble vitamins A, D, E, and K, while also providing essential fatty acids crucial for brain development (Lima et al., 2015).
Cashew kernels are a valuable source of essential vitamins, including pantothenic acid (vitamin B5), pyridoxine (vitamin B6), riboflavin, and thiamine (vitamin B1) These nutrients play a crucial role in the body's metabolism of proteins, fats, and carbohydrates at the cellular level, highlighting their importance for overall health (Olife et al., 2013).
Cashew kernels are a nutrient-dense food, rich in essential minerals such as manganese, potassium, copper, iron, magnesium, and zinc, making them an excellent daily addition to prevent deficiency diseases (Olife et al., 2013) The magnesium in cashews plays a crucial role in lowering blood pressure and reducing the risk of heart attacks, while also working with calcium to support bone health Additionally, cashews are packed with micronutrients that enhance iron metabolism, promote red blood cell production, and strengthen the immune system (Agboola, 2022) Their high copper content helps combat free radicals and contributes beneficial phytochemicals and antioxidants to overall health (Olife et al., 2013).
Table 2.1: Some nutritional components in 100g of edible cashew kernels
Unit Content Unit Content Components Components
(Source: Vietnamese Food Composition Table, 2007)
2.1.4 Potential and challenges of cashew kernels in the market
Strengths: According to statistics from the General Department of Customs, cashew kernels exports in December 2023 reached 63 thousand tons, equivalent to $343 million,
Potential and challenges of cashew kernels in the market
For the whole year 2023, cashew kernels exports hit the target of 644 thousand tons, equivalent to $3.6 billion, increasing by 24% in volume and 18% in value compared to
2022 With this result, the cashew industry exceeded its $3.05 billion plan by 18% This has also been the highest result in many years.
In 2023, exports of cashew kernels experienced significant growth in key markets, including the United States, China, and the Netherlands Notably, exports to the United States reached $885 million, reflecting a 5% increase from 2022 and representing nearly 25% of the total export value for cashew kernels.
According to the Communist Party of Vietnam Online Newspaper, Vietnam's cashew production and export capabilities in 2023 highlight the country's strengths in this sector The export of cashew kernels not only enhances the added value of agricultural products but also generates employment opportunities for workers, allowing Vietnam to meet domestic demand and reduce reliance on imports.
The variety of processed products in Vietnam, particularly cashew kernels, remains limited It is essential to actively develop final products for the local market to enhance the added value of agricultural resources This approach not only ensures better control over raw materials and markets but also contributes positively to society By diversifying domestic product offerings, Vietnam can reduce reliance on imports and strengthen its agricultural sector.
Honey powder, benefits, and changes in honey powder during product
Honey, produced by honeybees (Apis mellifera) from flower nectar, is a unique natural product with significant nutritional, cosmetic, therapeutic, and industrial benefits Comprising primarily fructose (38%) and glucose (31%), honey is a supersaturated sugar solution that also contains phenolic compounds, minerals, proteins, free amino acids, enzymes, and vitamins Research indicates that honey possesses various health benefits, including antioxidant, anti-inflammatory, and antibacterial properties, making it a valuable resource in treating numerous human ailments.
(2012), digestive, cardiovascular and neuroprotective properties (Liu, 2011) provides protection.
Table 2.2: Some nutritional components in 100g of honey
Components Unit Content Components Unit Content
(Source: Vietnamese Food Composition Table, 2007)
Honey is a versatile natural sweetener that enhances the flavor and nutritional value of various foods It serves as an excellent marinade for meats, imparting a delightful aroma and appealing color when cooked Additionally, honey adds sweetness to baked goods, smoothies, and other culinary creations.
To easily facilitate blending of honey with other ingredients, honey powder has been created by removing moisture from raw honey, which is then ground into a fine powder.
Honey powder maintains the unique flavor and nutritional benefits of raw honey, making it a versatile ingredient that blends seamlessly with dry ingredients and enhances the taste of various foods and beverages It provides the signature sweetness of honey without altering moisture levels or textures, and boasts a longer shelf life than liquid honey when stored properly Commonly utilized in food processing, honey powder is ideal for boosting flavor in beverages, gels, snacks, baked goods, and coated fried nuts.
Honey powder plays a crucial role in the product, as its interaction with amino acids and sugars during frying at 153°C results in an attractive yellow hue and enriches its unique aroma.
Gum arabic, uses and changes during processing and storage
Gum arabic, also known as gum acacia, gum sudani, and Senegal gum, is a natural gum derived from the hardened sap of two Acacia tree species: Senegalia senegal and Vachellia seyal.
Gum arabic, a complex blend of glycoproteins and polysaccharides mainly composed of arabinose and galactose, is an edible and water-soluble substance It serves essential roles in the food and soft drink industries as a stabilizer, thickener, emulsifier, and encapsulating agent, recognized by the E number E414 in Europe and 1414 in the US (Anderson & Eastwood, 1989).
Commercial gum arabic is primarily sourced from two species: Acacia senegal and Acacia seyal The powdered form of gum arabic is widely utilized due to its ivory white color and water-solubility, making it easily dissolvable in both cold and hot water at concentrations of up to 50% Additionally, gum arabic plays a crucial role in preventing sucrose crystallization, enhancing its functionality in various applications.
Gum arabic serves as a stabilizing additive in fried cashew kernels soaked in syrup and honey powder, effectively limiting sucrose crystallization and enhancing the syrup's adhesion to the cashew kernels.
Rapeseed oil, uses and changes during processing and storage
Rapeseed oil, derived from the Brassica napus L plant of the Brassicaceae family, is commonly utilized in food processing to enhance the flavor of fried foods Beyond its culinary uses, rapeseed oil is recognized for its numerous health benefits attributed to its rich nutritional profile.
Rapeseed oil is a popular and affordable cooking oil used globally, commonly found in salad dressings and various baked and fried dishes It is low in saturated fat and high in unsaturated fats, making it a healthy choice (Dupont et al., 1989) Rich in the omega-3 fatty acid alpha-linolenic acid, rapeseed oil offers significant cardiovascular benefits, including lowering blood pressure and reducing the risk of heart attacks Additionally, its high omega-6 fatty acid content can support overall health, though excessive omega-6 may lead to inflammation Fortunately, rapeseed oil maintains a balanced 1:2 ratio of omega-3 to omega-6 fatty acids, which experts consider ideal (Zhang et al., 2021).
Table 2.3: Nutritional composition in 100gram of rapeseed oil
Unit Content Unit Content Components Components
Saturated fat bì 12 Vitamin E mg 20
Unsaturated fat g 88 Vitamin A plus IU 9200
(Information provided by the manufacturer on the Simply rapeseed oil bottle label)
Fried cashew kernels coated with syrup and honey powder benefit from rapeseed oil, which serves as both a heating agent and a nutrient-rich component in the final product According to Nurhan Dunford, this oil enhances the overall quality and nutritional value of the cashews after frying.
(2018), rapeseed oil has a smoke point of 220-230°C, so frying cashews in rapeseed oil at 153°C allows the product to cook quickly and become flavorful without harming consumer’s health.
The drying process and changes in ingredient composition during drying
Drying is a crucial operation in food processing that effectively removes water from food using hot air flow or vacuum techniques, thereby inhibiting enzyme activity and microbial growth, which helps reduce spoilage and extend shelf life (Bennamoun & Li, 2018; Petikirige et al., 2022) This process not only prolongs the shelf life of fruits but also alters their physical, chemical, sensory, and nutritional qualities, creating new functionalities (Khan et al., 2018) The extent of these changes is influenced by the nature of the raw material, as well as the time, temperature, and drying equipment used.
In food processing, the drying method is essential for preserving the quality of dried fruits, powders, cereals, nuts, meat, fish, and dairy products Each food type requires specific drying regimes to retain its unique characteristics Implementing drying techniques across diverse food products enhances market diversification and boosts economic value.
To process fried cashew kernels coated with syrup and honey powder, soaked cashews are dried in a hot air dryer to reduce moisture content and achieve the desired level This drying not only enhances the adhesion of the syrup and honey powder mixture on the cashews but also ensures they become crunchier and more aromatic by releasing volatile compounds during the process.
The frying process and changes in ingredient composition during frying lãi
Frying is a cooking method that involves immersing food in hot oil at high temperatures, where the oil acts as both a heating agent and a flavor-enhancing component This technique is commonly utilized in the industrial preparation of various foods, including fries, snacks, and fried nuts.
It is also a method that helps quickly cook food and has long been familiar to households (Oke et al., 2018).
Fried cashew kernels coated with syrup and honey powder are prepared by frying dried cashews in rapeseed oil at 153°C for 4 minutes This process not only serves as a heating method but also integrates rapeseed oil into the final product Frying reduces surface moisture, which helps prevent microbial growth and enhances the cashews' texture and flavor Additionally, the high temperature gels the syrup, improving adhesion to the cashews and contributing to their appealing color and crunchiness, while effectively inhibiting most microbes and enzymes (Zelenakova et al., 2019).
Moisture content of cashew kernels and its impact on product qualIty
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3.3.2.1 Effects of temperature on the physicochemical properties of fried cashew kernels during storage
This experiment investigated the effects of various storage temperatures—high (45°C), room temperature (29 ± 2°C), and cool (5 ± 1°C)—on the half-life (t12) of fried cashew kernels Five-gram portions of the kernels were hermetically sealed in polyethylene bags and double-packed in laminated aluminum foil bags (0.16 cm thick) The samples were stored under accelerated temperature conditions for durations of 0, 7, 14, 24, 34, and 40 days Key parameters analyzed included moisture content, reducing sugar, total sugar, peroxide values, and sensory evaluation, conducted at 7-day intervals from day 0 to day 14 and every 10 days from day 24 onward.
3.3.2.3 Effects of relative humidity on the physicochemical properties of fried cashew kernels during storage
A series of hermetic glass desiccators (700ml) were prepared with saturated solutions of sodium hydroxide, potassium acetate, magnesium nitrate, sodium chloride, and potassium chloride, achieving relative humidity levels of 10%, 23%, 34%, 76%, and 84%, respectively These desiccators were set up 24 hours before the experiments A disc containing 2 grams of fried cashew kernel was placed in each desiccator and stored at room temperature (29±2°C) After 14 days of conditioning, the samples underwent analysis for moisture content, reducing sugar, total sugar, peroxide values, and sensory evaluation.
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Figure 3.2: Determination of equilibrium moisture content using a desiccator
Analysis of physicochemical properties ¿25-25 +S+£++£+s£+seeereerrrrrs 21
Determination of reducing sugar and total sugar conten(
The sugar content was analyzed using the method established by Negrulescu et al (2012), with additional details available in Appendix 3.1 Additionally, the total sugars content was measured following the procedure outlined by Baskan et al.
Apak, 2016) Refer to Appendix 3.2 for further details.
The reducing sugar and total sugar contents were calculated using the formula:
D _ reducing sugar or total sugar content in the sample to be determined. x reducing sugar or total sugar content in the measured sample. df dilution factor
V mifial volume of the standard solution (ml). m Iniial weight of the sample (g).
Determination of moisture content . 5 252 S2 S2 *+££*£+zzzEerrrerrres 21
The moisture content of cashew kernels was analyzed using the oven-drying method as per TCVN 10788:2015 standards Initially, the kernels were ground into small pieces, and a 5g sample was placed in a pre-weighed container, with the container's weight recorded The sample and container were then dried in an oven at 105°C until a constant weight was achieved, ensuring accurate moisture measurement.
The moisture content of the sample was calculated using the formula:
@w Moisture content of cashew kernels (%) G1 Weight of the container and sample before drying (g) G2 Weight of the container and sample after drying (g)
G Weight of the analyzed sample (g)
Determination of the peroxide vaẽue - +22 +2 + +22 Ê+sszsessrseerers 22
The peroxide value was sent to Eurofins Sac Ky Hai Dang Company Limited for analysis with samples from different storage conditions.
Sensory evaluation of fried cashew kernels . ++-xc+c++xxeerxers 22
The product underwent a sensory evaluation using a hedonic scoring test, as outlined in the Food Sensory Analysis technique document by Ha Duyen Tu This assessment utilized a scoring scale from 1 to 7, with 7 indicating the highest levels of appealing color, crispiness, fresh odor, and overall preference Scores were recorded as positive integers.
Calculation of kinetic parameters .ccececeeceeseeeceesececeeseeeceeseeeseeseeeeeaes 22
The kinetic change of cashew kernels was reported to follow first-order reaction rate constants Kha et al (2015) using the following equations:
In C = In Cọ — kt Where:
The concentration at time zero (C0) and the degradation rate constant (k, in days⁻¹) can be determined from the slope of the natural logarithm plot of C/C0 against storage time (in days) Additionally, the half-life of the substance at a specific temperature is calculated using the equation t½ = ln(2)/k.
Each experiment was conducted in triplicate (n = 3), and results were presented as mean ± standard deviation Data processing and graphing were performed using Excel 2019, while the analysis of variance (ANOVA) was conducted using SPSS version 21 to evaluate differences among the experimental formulations.
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Quality analysis of raw cashew kerneÌs - +s-s se ss+tssrrrrrerrrrrrrrrrree 24
Cashew kernels were inspected for color, odor, and moisture content prior to experimentation, adhering to TCVN 12380:2018 standards These raw cashew kernels must exhibit a characteristic shape and a uniform color, with acceptable shades ranging from gray to pinkish-white, light gray to gray, and light brown to brown, all reflecting the product's quality Furthermore, the nuts should have a uniform size, be free from foreign odors, appear unblemished, and contain no live insects, ensuring their suitability for experimental use.
The moisture content of raw cashew kernels is a vital factor, recorded at 5.28% ± 0.10, which must remain below 10% to meet the rigorous standards of TCVN 12380:2018 Adhering to this moisture range is essential, as it influences the texture, shelf life, and overall quality of the nuts, making them suitable for diverse applications.
Effects of storage temperature on the physicochemical properties of the fried
The level of reducing sugar is a crucial quality standard for fried cashew kernels, as these sugars act as reducing agents due to their free aldehyde or ketone groups This factor significantly influences the quality of various nuts, particularly fried cashew kernels, hazelnuts, macadamia nuts, and almonds, affecting both flavor and appearance during roasting and frying A statistically significant difference (P