74 

Journal homepage: www.fia.usv.ro/fiajournal 

Journal of Faculty of Food Engineering,  

Ştefan cel Mare University of Suceava, Romania  

Volume XVII, Issue 1- 2018, pag.  74 - 80  

 

 

 

USE OF WALNUTS (JUGLANS REGIA L.) WASTE FROM PHYSICAL 

EXTRACTION OF OIL TO PRODUCE FLOUR AND SWEETS 

 
*Valentina BANTEA-ZAGAREANU 

 Faculty of Food Technology, Technical University of Moldova, 

Town, Country, 168 Stefan cel Mare blvd., MD-2004 Chisinau, Republic of Moldova 
*Corresponding author:  v_bantea@yahoo.com 

Received 16th October 2017, accepted 23th March 2018 

 
Abstract: The purpose of the research consists in enhancing the value of the secondary 
products of the seed oil industry, especially of the defatted walnut flour (Juglans regia L.). By 

adding it in the composition of sweets, the aim is to obtain a new product, with a balanced 

ensemble of nutritional substances – fats and carbohydrates. Also, it will be possible to enlarge 

the assortment of the confectionery products, which due to the low amount of carbohydrates, 
could be consumed by persons of all age, without the risk of sickening of diabetes.Physico- 

chemical methods were used to determine humidity, amount of fats, acid value, peroxide value 

and amount of total ash as well as the defatted walnut flour’s quality, used in the production of 
sweets. The product was subjected to physico – chemical, microbiological and sensory analysis. 

Due to the amount of fats contained in defatted walnut flour, the peroxide value in the finite 

product was determined. The aim is to notice wether fats’ oxidation occurs during storage 
which results in the worsening of organoleptic characteristics of the product – taste and flavor. 

The results show microbiological stability of the product, absence of oxidation of fats contained 

in defatted walnut flour, confirmed by sensory analysis. No taste or flavor drawbacks of the 

product that could be caused by fats’ oxidation were identified. 
 

Keywords: dried fruits, fats, oxidation, peroxide value, sweets, defatted walnut flour, inulin. 

 
 

 

1. Introduction 
 

Confectionery products are food 

products with a high amount of sugar, 

with sweet taste and different forms, 

composition, consistency, structure, 

flavor and are characterized by a high 

energetic value, good digestibility, 

having a pleasant taste, flavor and look. 

Confectionery products are divided into 

two categories - bakers' confections and 

sugar confections. The main ingredient 

of confectionery products is sugar or 

sugar substitutes (sweetener). Sweets 

are products manufactured form sugar,  

 

 

 

glucose syrup, cocoa products, peanuts,  

walnuts’ kernels, dairy products, food 

coloring and flavors, and other 

ingredients [1-3].  

Production volume of sugar confections 

in Republic of Moldova shows a 

quantitative evolution from 12.0 

thousand tons in 2005 up to 14.0 

thousand tons in 2015, but it doesn’t 

exceed the production volume of 

bakers’ confections, which is 2.5 times 

higher in 2015 (33.6 14.0 thousand 

tons) [4]. Results are given in figure 1. 

 

http://www.fia.usv.ro/fiajournal


Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - 

Suceava Volume XVII, Issue 1  – 2018 

 

 

Valentina BANTEA-ZAGAREANU, Use of walnuts (Juglans regia L.) waste from physical extraction of oil to 

produce flour and sweets, Food and Environment Safety, Volume XVII, Issue 1 – 2018, pag. 74 – 80 

 

 
75 

 
Fig. 1. Quantitative evolution of production 

volume of sugar confections (2005-2015), 

thousand tons [4] 

 

Nuts are one of the main raw materials 

used at sugar confections’ 

manufacturing. The basic characteristic 

of nuts is high amount of fats and 

proteins, which determines high 

energetic value of confectionery 

products. Nuts are used at obtaining of 

marzipan and praline masses, at the 

production of caramel fillings, candied 

roasted nuts, dragees, halvah or are 

added in chocolate tablets, because of 

high tasteful qualities, which it gives to 

the finite product [5, 6]. 

Confectionary products were used to 

investigate walnut waste value 

determination. The choice of 

confectionary products for the 

investigation was determined due to 

their heterogenic structure, which often 

contains low amount of essential 

nutrients. Supplementing confectionary 

products with walnut waste would 

improve their structure and nutrition 

value as well as reduce their cost. 

Products from halva and sponge cake as 

well as cookies „Macarons” were 

chosen for this investigation. The 

quality of elaborated confectionary 

products depends majorly on the 

grinding size and antioxidant properties 

of walnut waste, which also has a big 

impact on the organoleptic and 

physiochemical qualities of the final 

products [7].  

In this paperwork we studied use of 

defatted walnut flour in Amaretti 

cookies production, which are normally 

produced on the base of almond flour 

according to their classic recipe. It was 

detected that adding walnut waste to the 

cookies recipe positively influences on 

their organoleptic and physiochemical 

properties as well as the microbiological 

stability reducing their costs [8]. 

One of walnut waste use in food 

industry is its use in milk industry to 

produce a certain type of cheese. This 

type of cheese contains 1.5-2 % of 

walnut waste from the whole mass of 

the product. The walnut waste use is 

more preferable than one of the walnuts 

due to the fact that walnut waste 

contains lower amount of oil as well as 

it is oxidized slower, extending the final 

product shelf life. In such a way, walnut 

waste use improves functional and 

organoleptic properties of the product, 

increases its nutrient value and shelf life 

[9]. 

Defatted walnut flour (Juglans regia L.) 

is  a rich source of  lecithin, vitamins  

(A,  B, C, E, P), micro- and macro- 

elements (sodium, potassium, iron, 

iodine, phosphorus, magnesium, 

calcium), biologically active substances 

which helps at improvement of heart’s 

activity, purification of blood vessels, 

brain’s stimulation in period of 

intensive intellectual activity, helps at 

muscles’ strengthening and at removing 

of tiredness caused by physical effort. 

Another important component of 

defatted walnut flour is cellulose. It has 

to remove toxins from the organism, 

this process improving the state of skin 

and speeding the loss of weight. The 

amount of vitamin C in defatted walnut 

flour is 5 times higher than in red 

currant.  

Iodine which is contained in defatted 

walnut flour helps at maintaining of 

thyroid’s health [10]. 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - 

Suceava Volume XVII, Issue 1  – 2018 

 

 

Valentina BANTEA-ZAGAREANU, Use of walnuts (Juglans regia L.) waste from physical extraction of oil to 

produce flour and sweets, Food and Environment Safety, Volume XVII, Issue 1 – 2018, pag. 74 – 80 

 

 
76 

Because of high amount of proteins and 

their partial solubility, defatted walnut 

flour (Juglans regia L.) has good 

functional properties and may be a good 

source of functional and protein 

ingredient in heterogeneous food 

systems like emulsions, foams, 

suspensions [11]. 

Also, antioxidant properties of walnuts 

are well outlined from peanuts and 

almonds’ properties, a fact which 

increases the use of walnuts not only for 

the pleasant taste and flavor of 

confectionery products, but also for 

extending their term of validity [12]. 

 

2. Materials and methods 
 

For the research were used raw 

materials such as by-product from the 

production of cold-pressed walnut oil 

(Juglans regia L.), harvest of 2014 year, 

Kogalniceanu kind [13], dried plums 

[14], raisins [14], powdered sugar [15], 

the dietary fiber – inulin, cocoa powder 

[16] and ascorbic acid (E300) [17]. 

 

 
 

Fig. 2. Defatted walnut flour (Juglans regia L.), harvest of 2014 year (produced under laboratory 

conditions 

 

The technique for making dried plum or 

raisins sweets with addition of walnut 

waste implies raw materials preparation 

for production process – inspecting and 

washing dried fruit, separating walnuts 

waste from ferromagnetic impurities, 

sorting according to the grind size, 

auxiliary materials screening (cocoa and 

sugar powder, inulin). After being 

washed, dried plums are steamed and 

boiled in sugar syrup.  

Plums and raisins are dried until their 

humidity level is decreased to 20-25 %, 

but walnut waste is heated at 60-65 ºC 

during 30-35 minutes to reduce its 

humidity level.  

To obtain the recipe mixture, plums and  

raisins are grinded up, dried walnut 

waste and auxiliary materials (cocoa 

and sugar powder, inulin and ascorbic 

acid) are added. 

Then, bases of sweets are formed, being 

further covered with chocolate glaze, 

which was filtered and warmed up to 

29-32 ºC preventively.  

Glazed sweets are cooled to +4 - +6 ºC 

during 5-7 minutes. 

For determination of defatted walnut 

flour’s quality, which was used for 

production of sweets, were used physic- 

chemical methods, for determination of 

humidity [18], amount of fats [19], acid 

value [20], peroxide value [21] and 

amount of total ash [22].  

Sensory analysis of defatted walnut 

flour was performed according to 

GOST 13979.4-68 [23]. 

For sensory analysis of sweets with 

addition of walnut waste an analytical 

method of appreciation was applied 5 

point scale. There is a 5 point scale to 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - 

Suceava Volume XVII, Issue 1  – 2018 

 

 

Valentina BANTEA-ZAGAREANU, Use of walnuts (Juglans regia L.) waste from physical extraction of oil to 

produce flour and sweets, Food and Environment Safety, Volume XVII, Issue 1 – 2018, pag. 74 – 80 

 

 
77 

appreciate each feature (taste, flavor, 

composition, aspect) [24]. 

Taster team consisted of 7 members 

(students and teaching stuff). Each 

taster had an individual file for sensory 

analysis. Based on the results, a general 

file as well as a sensory profile of 

defatted walnut flour was created.  

In table 1 presented scale of 

appreciation grades. 
 

Table 1. 

5 point scale of appreciation grades  

[24, p.91]. 

 

Grade of 

appreciation 

Grade 

points 

General 

description of 

appreciation 

grades 

Very good 5 Exceptional qualities 

Good 4 Adequate qualities 

Satisfactory 3 With some defects 

Unsatisfactory 2 With evident defects 

Poor 1 With strong defects 

Very poor 0 Unacceptable 

 

For determination of microbiological 

characteristics of sweets were 

determined the quantity of mesophilic 

aerobes and facultative anaerobes [25], 

the number of yeasts and molds [26], 

presence of coliform bacteria 

(Escherichia Coli) [27]. 

Because of amount of fats contained in 

defatted walnut flour, was determined 

peroxide value [21] in the finite 

product. The goal is to notice if during 

the storage take place the fats’ oxidation 

which has as result worsening of 

organoleptic characteristics of the 

product – taste and flavor. 

 

3. Results and discussion 
 

The new product contains vegetal 

proteins from walnuts’ kernel, with a 

high biological value. Fats are 

represented by the oil remained in the 

cake after the nuts’ pressing and the 

carbohydrates are represented by the 

powdered sugar and dried fruits. Even if 

the carbohydrates’ quantity is large, the 

major are fibers, which are contained in 

the dried fruits. 

In table 2 are presented physic-chemical 

characteristics of the defatted walnut 

flour, determined in the research. To get 

valid results, 5 analyses were carried 

out identifying experiment data 

precision  
 

Table 2. 

Quality characteristics of defatted walnut 

flour. 

 

Physic-chemical 

characteristics 

Experimental 

values 

Technical 

conditions 

Amount of fats, 

% 
35.26 ± 0.2 41.0-45.0 

Humidity, % 7.62 ± 0.2 5.8 

Amount of total 
ash, % 

2.53 ± 0.03 4.0 

Peroxide value, 

millimoles per 

kilogram 

8.82 ± 0.1 10.0 

Acid value, mg 

KOH/g oil 
1.79±0.01 4.0 

 

It shows that experimental values are 

according to technical acts. It means 

that this defatted walnut flour can be 

used for manufacturing of sweets. 

In the production recipe was used inulin 

(the dietary fiber), obtained under 

laboratory conditions. Inulin is also a 

sugar replacement. The new product 

received a good appreciation from the 

tasters’ team. Equally was appreciated 

the consistence, taste and flavor of the 

sweets (4,85), while the structure is 

considered to be a critical parameter [2]. 

Sensory profile of the product with the 

defatted walnut flour is shown in figure 

3. 

https://en.wikipedia.org/wiki/Millimole
https://en.wikipedia.org/wiki/Kilogram
https://en.wikipedia.org/wiki/Potassium_hydroxide


Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - 

Suceava Volume XVII, Issue 1  – 2018 

 

 

Valentina BANTEA-ZAGAREANU, Use of walnuts (Juglans regia L.) waste from physical extraction of oil to 

produce flour and sweets, Food and Environment Safety, Volume XVII, Issue 1 – 2018, pag. 74 – 80 

 

 
78 

 
 

Fig. 3. Sensory profile of the product with the defatted walnut flour 
 

 

This thing is owed to an insufficient 

mixing of defatted walnut flour with 

dried fruits’ mass. From tasters’ 

observations was noticed that they 

would prefer a product, which will have 

a higher content of defatted walnut 

flour, which will contribute at 

increasing of energetic value of the 

product. 

Because of actual tendency to release 

on market products which have a long 

term of validity, is important to study 

and check the parameters, which can 

have a negative influence above the 

product at the storage. 

The oil content that remains in walnut 

waste after cold pressing 

(approximately 40 %) is perishable. 

Oils which walnut waste contains can 

be affected by the process of rancidity, 

which leads to product taste change. 

Rancidity is a process of oil oxidization 

caused by oxygen from the air and it 

can be developed by microorganisms. 

This process causes products taste and 

flavor change. To stop or avoid 

rancidity, various inhibitors of free-

radicals reactions or inhibitors which 

create heavy-metal complexes are used 

(сitric acid, ascorbic acid). Oxidization 

reactions are exothermic thus, if storage 

or transportation conditions are 

unsatisfactory, walnut waste can be 

self-ignited [12].  

 

 

For the sweets with addition of defatted 

walnut flour is important to know if the 

fats are oxidized, because this process 

can cause depreciation of sensory 

characteristics – taste and flavor.  

After determination of peroxide value in 

sweets with defatted walnut flour, using 

a method for confectionery products, 

can be said that after a month peroxide 

value grew up, but the value (4,56 

millimoles per kilogram) is according to 

the peroxide value for walnuts’ oil, 

which maximum is 10,0 millimoles per 

kilogram [28].  

So, for establishing the term of validity 

for this product is necessary to continue 

the research and check monthly physic-

chemical parameters. 

Also, is necessary to establish suited 

conditions for the storage, taking into 

account all the ingredients from the 

product and processes which can take 

place at different temperatures. 

Microbiological stability is also an 

important element, which should be 

taken in account before releasing a 

product on market. According to [29], 

the quantity of mesophilic aerobes and 

facultative anaerobes are 5,0·10³ 

colonies per gram of product. Evolution 

of quantity of mesophilic aerobes and 

facultative anaerobes at the storage of 

sweets with dried fruits is shown in 

figure 4. 

https://en.wikipedia.org/wiki/Millimole
https://en.wikipedia.org/wiki/Kilogram
https://en.wikipedia.org/wiki/Millimole
https://en.wikipedia.org/wiki/Kilogram


Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - 

Suceava Volume XVII, Issue 1  – 2018 

 

 

Valentina BANTEA-ZAGAREANU, Use of walnuts (Juglans regia L.) waste from physical extraction of oil to 

produce flour and sweets, Food and Environment Safety, Volume XVII, Issue 1 – 2018, pag. 74 – 80 

 

 
79 

As we can see, even after 4 months of 

storage at temperature 18±3 ºC, the 

number of aerobic and optionally 

anaerobic microorganisms doesn’t 

exceed the maximum value. 

Microbiological load of the sweets with 

defatted walnut flour is poor, because 

molds and yeasts were not identified 

after examination. The main cause is the 

lack of conditions, which can cause 

molds and yeasts’ growth.  

Humidity of sweets, determined by the 

method [30], is 21 %, value which is 

corresponding with technical conditions 

[29]. 

 

 
 

Fig. 4. Evolution of quantity of mesophilic 

aerobes and facultative anaerobes at the 

storage of sweets with dried fruits and 

defatted walnut flour at temperature 18±3 ºC 

 

Escherichia Coli wasn’t identified in 

the sweets. This means that during the 

manufacturing and storing them were 

respected hygiene conditions of 

equipment used during the process, of 

storage space and the staff which 

participated in the manufacturing 

process respected good hygiene 

practices. 

 

 

 

 

 

 

4. Conclusions  
 

Sweets with body made from dried 

fruits can be a good alternative instead 

of confectionery products, which 

contain large quantities of sugar – 

caramels or fondant sweets. The 

substitution of chocolates or caramels 

with sweets made from dried fruits and 

defatted walnut flour will stop gaining 

weight, but receiving the same pleasure 

from eating sweets. Such sweets contain 

a small quantity of sugar, vitamins of all 

groups, necessary for intellectual and 

physical growth of children. 

Application of defatted walnut flour 

(Juglans regia L.) at manufacturing of 

sweets with dried fruits has an influence 

about energetic value of the product, 

enriching them with a balanced quantity 

of fats. In comparison with other 

confectionery products, where whole 

nuts are used, the presented product 

contains a smaller quantity of fats, but 

the same of proteins, which has the 

same benefits for human’s organism. 

Also, the small quantity of fats from 

defatted walnut flour has a positive 

influence above microbiological 

stability of sweets, and using of 

ascorbic acid protects fats from defatted 

walnut flour from oxidation, which can 

affect organoleptic characteristics of 

finite product. 

 

5. Acknowledgments 
 

This work was benefited from support 

through the 11.817.04.40A project, 

“Elaboration of methods to protect 

walnut lipids (Juglans regia L.) from 

oxidative degradation”, funded by the 

Academy of Science of Moldova and 

Moldavian Government. 

 

 

 

 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - 

Suceava Volume XVII, Issue 1  – 2018 

 

 

Valentina BANTEA-ZAGAREANU, Use of walnuts (Juglans regia L.) waste from physical extraction of oil to 

produce flour and sweets, Food and Environment Safety, Volume XVII, Issue 1 – 2018, pag. 74 – 80 

 

 
80 

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shrot-greckogo-oreha-istochnik-lecitina-

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powdered mustard seed cake. Methods for 

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content. 

[19]. GOST 13979.2-94 Oilcakes, oil meals and 
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[22]. GOST 13979.6-69 Oilcakes, oil meals and 

powdered mustard seed cake. Determination of 

ash content. 
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powdered mustard seed cake. determination of 

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[27]. SM ISO 4832:2013 Microbiology of food 

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[29]. GOST 4570-93. Sweets. General 

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substances. 

 


	1. Introduction