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Potato accessions- Chipping quality-Organic
SAGALLA, ESTHER JOSEPHINE D. APRIL 2007.
Chipping Quality of Potato Accessions Grown Organically in Different Production Sites in Benguet [ Master thesis ].
Benguet State University, La Trinidad, Benguet.
Adviser: Belinda A. Tad-awan, Ph.D.
The chipping quality of nine potato accessions grown organically in different production sites of Benguet was evaluated. The study aimed to determine the influence of different production sites on the chipping quality of potato accessions grown organically, identify the potato accession with the best chipping quality, and determine the interaction between the production site and potato accession on chipping quality.
Potatoes grown in Balili, La Trinidad (1,336 m asl; 18.360C; 71.81% RH) had relatively high yields and consistently produced tubers with good chip quality. Furthermore, the harvested potatoes had high dry matter content (20.78%), specific gravity (1.077), and chip recovery (82.74%). The potatoes also had one of the lowest sugar content (3.940Brix), thus, producing light yellow chips with no browning. The chips were also liked much by the panelists.
Potatoes harvested from Longlong (1,342 m asl; 20.490C; 80.81% RH) and Cabutotan (1,588 m asl; 16.190C; 87.50% RH) also yielded well with a good chipping quality and high chip recovery. Moreover, the chips produced were light yellow but were liked moderately by panelists.
Accession 13.1.1 and 18.104.22.168 had the highest dry matter contents (20.03% and 20.47%), specific gravity measurements (1.074 and 1.084), and percent chip recovery (78.07 and 77.57). Also, they had the lowest sugar contents (3.880Brix and 3.910Brix), thus, producing the desired light yellow chips with no browning.
Production site and potato accession interacted significantly to affect dry matter content, sugar content, chip recovery, chip color, and specific gravity. This interaction means that both site and accession are important considerations in organic growing of potatoes for chipping.
Background of the Study
Potato varieties with high yield and acceptable processing quality are vital requisites in our local processing industries. However, varieties with such characteristics are limited. Only a few processing varieties such as Igorota, Kennebec, Atlantic, and Columbus are grown in the highlands. Thus, there is an increasing need to continuously evaluate more varieties or accessions that have good processing qualities.
One of the processed products set for commercial production is the potato chip. The chips first appeared during the mid 1850’s as a normal part of American cooking. The potato was most likely sliced from the axis of the tuber and then fried. It was only until a certain chef named George Crum sliced the tubers thin enough to become crunchy potato chips. The chips, originally called ‘potato crunches’ became popular in restaurants and grocery stores. They were eventually introduced to England and neighboring countries during the early to mid part of the 20th century (Harmon, 1998).
The potato chip industry continues to grow in countries worldwide including the Philippines. In fact, 400 to 533 metric tons of fresh potato tubers must be supplied merely for potato chip processing (Department of Agriculture
, undated). However, with the reported Philippine production of 68,000 metric tons (FAO, 2002), only a portion of it is usually suitable for processing. The Philippine government thus imports processed potatoes, which in 2001 were valued at $16,858,000.00 (Gagnon, 2002).
Importance of the Study
Potato processors use whatever is available to them at the time of processing. Some processors use a mixture of potato varieties which are both imported and locally produced. As a result, the quality of potato chips is greatly affected. For instance, potato varieties with high sugar content produce brown chips with bitter taste. Other varieties with low dry matter content produce soggy potato chips with high oil uptake and longer frying time.
Furthermore, two large-scale potato processors in Metro Manila mainly procure the Granola variety because it is readily available but not ideal for processing. It has low dry matter, high moisture content, and produces chips that easily brown during frying (FRLD, 1995)
Potatoes are mainly grown conventionally with the application of expensive chemicals and other synthetic compounds. When chipped, these potatoes were found to contain as high as 73% pesticide residue (Lang, 2005). Growing processing type potatoes organically is therefore a better alternative to conventional production methods. It is in fact claimed that organically grown potatoes taste better and contain more dry matter than conventionally-grown ones (Finesilver, 1980). Health wise, organically grown potatoes are safe foods that are free from toxic and harmful chemicals.
The location of production areas and the employed cultivation practices also influence important quality factors of potato tubers for processing such as specific gravity, dry matter, sugar content, and others. Thus, it is necessary to grow potatoes in several locations to evaluate processing quality of different accessions.
Several studies have been conducted to evaluate the suitability of potato varieties to chipping. However, the varieties identified for processing are limited and often susceptible to diseases.
It is therefore important not only to identify an appropriate potato accession that can give good quality chips but also determine the effect of location of production to potato chip quality.
Time and Place of the Study
The study was conducted at Englandad, Sinipsip, Loo, Balili, Longlong, and Cabutotan where the potatoes were organically grown. The harvested potatoes were processed at the College of Agriculture Complex, Benguet State University, La Trinidad.
The study was conducted from October 2005 to March 2006.
REVIEW OF LITERATURE
Origin and Distribution of Potato Chips
Piecing together how chips spread between 1853 and the early part of the 20th century is difficult. It is, however, assumed that the potato chips first appeared in 1853 at Saratoga Springs, New York, which is considered its place of origin. A certain cook named George Crum sliced the tubers very thinly to produce crispy potato chips. The potato chips were then introduced to England in 1921 (Harmon, 1998) and eventually to other parts of the world.
The Potato Chip Industry
The potato chip industry has a demand for fresh potato up to 533 MT daily. However, this demand for potatoes intended for processing is not met by local production in volume and quality (HARRDEC, 1998).
Baguio and Benguet are the primary suppliers of potatoes for chips in the Philippines. A newly emerging supplier is Mindanao. Metro Manila has been absorbing about 50% of the potato chips. However, sales of potato chips in the Philippines declined from 14% in 1990 to 6% in 1992 (Dep’t of Agriculture, undated).
Suitability of Potato Varieties for Chipping
Production and yield
. Planting area and production of processing are very limited. The main reasons are lack of suitable varieties for processing, little access of potato farmers to these varieties, limited knowledge of industries on the standards and requirements of processing potatoes, and susceptibility of processing varieties to pest and diseases (Kaiyun
High tuber yields and quality are also important determinants for the suitability of a given variety for large-scale local production. Varieties with higher specific gravity and dry matter tend to have higher yields and better quality of finished chips. Moreover, color of chips depends on sugar content of tubers (Tawfik
Well-adapted potato cultivars that require fewer days to produce high marketable yields would be specifically advantageous in much of the East. Unlike most western production areas, short seasons (90-110 days) prevail in much of the East, especially in northern areas. Early-maturing cultivars would also be useful in intensively managed systems (e.g. organic, hoop houses, etc), especially if access to the earliest markets and/or escape from persistent disease and insect pressure (NERA, 2002).
. Choosing varieties is very important for chip processing, however, small-scale producers use varieties that are available to them at the time of processing. As a result, the quality of chips varies tremendously, as the processing quality is a function of both physical and chemical factors of the tubers (Illeperuma and Wickramasinghe, 2000).
Moreover, potato varieties for processing suffer from poor varietal improvement (Dep’t of Agriculture, undated). Locally grown potato varieties in the country have very low dry matter content (15% to 18%) which is not suitable for processing. The development of suitable varieties (i.e. adapted to the local growing conditions and acceptable to processors and consumers) is therefore very necessary not only to help local farmers but also to develop the country’s potato processing industry (HARRDEC, 1998).
Several potato varieties have been identified to be adaptable to the country’s agro-climatic conditions such as the
for chips, and the
for both chips and fries. These varieties are now being tested in various experimental farms in the Cordillera and in the growing areas of Mindanao (Department of Agriculture, undated).
Dry matter content and specific gravity
. Potato varieties with high dry matter content are considered suitable for chips as the dry matter content is associated with mealiness, crispness, and reduced oil uptake in the fried chips (Illeperuma and Wickramasinghe, 2000).
Potato varieties for chipping has to have high dry matter content (19% and above). High dry matter content gives high chip yield with low fat content. Further, to obtain light colored chips, the reducing sugar content should be less than 0.2% (NPRCRTC, undated).
For the production of potato chips, varieties with dry matter content of 22-24% are required. The content of reducing sugars in the potato is also a determining factor with respect to the suitability of a potato variety for processing. Usually, the lower the reducing sugar content, the better the quality of the product. Potato varieties with 0.2% reducing sugar are acceptable for chips (Coumou, 1991).
The specific gravity or the dry matter content of potatoes are important because it influences the uptake of fat or oil during frying. Higher yield of processed products and lower oil uptake is a result of potatoes with high specific gravity (Verma, 1991).
High specific gravity is particularly important in the production of potato varieties for chips because of greater surface area to volume ratio in chips. Moreover, chip crispiness and lack of oiliness increases with increasing specific gravity (Scanlon, 2006).
. Processors prefer varieties that are best suited to produce light colored chips. However, maintenance of the desired color is the major problem associated with the chipping industry. The varieties used have inherent differences with respect to their chip color. These varieties contain different levels of reducing sugar, which are used to predict the suitability of potato tubers for chip processing, as they are often responsible for color development (Illeperuma and Wickramasinghe, 2000).
A reducing sugar content of 0.25 to 0.30 mg-g^sup-1^ fresh weight or 0.025% to 0.030% on fresh weight basis is the maximum concentration allowed in tubers used for chips (Oltmans and Novy, 2002).
Potatoes destined for making chips, French fries and other fried products, need to have low sugar content to avoid browning of the finished product. The sugar content of potatoes is determined by the genotype and several pre and post-harvest factors (Kumar
. Potato chipping varieties should have round and uniform tuber shape, light brown tuber skin color, shallow eye depth, and free from defects. Moreover, these varieties must have low reducing sugar (
0.2%) and moderate dry matter content (20-25%) (Kaiyun, 2004).
Large round tubers are preferred by the chipper, since their size and shape facilitate the removal of the peel more efficiently and with less solid loss. Further, cultivars with shallow eyes and few in number are to be preferred. If the eyes are deep, it is necessary to peel for longer periods of time to remove the eye. Potato varieties with high specific gravity are also preferred because they have been shown to absorb less cooking oil during the chipping process (Gould, 1988).
Potato Chip Quality
Good quality potato chips have a light color with little vascular discoloration. The color of potato chips depends on the reducing sugar content of the potatoes. Potato chips must also have a pleasing and desirable flavor, thus potatoes used in chipping must not be bitter or have other off-flavors. The flavor of potato chips is more complex than that of boiled, baked or mashed potatoes, since the cooking temperatures are higher, and the absorbed oil contributes to the overall flavor profile of the product (Scanlon, 2006).
An important factor influencing potato chip color is the level of reducing sugars, glucose and fructose, at the time of frying. Glucose and fructose are the products of sucrose hydrolysis mediated by the enzyme invertase. Increasing concentrations of reducing sugars in the tuber correlate with darker chip color (Oltmans and Novy, 2002).
Chipping quality is a genetically transmissible character. Potatoes that produced light-colored chips after cold storage and reconditioning were shown to transmit the ability to produce light-colored chips to their progenies (Oltmans and Novy, 2002).
Many factors contribute to potato chip quality. This includes maturity of tuber, shape, thickness, skin, peel, eyes, skin and flesh color, defects, specific gravity, temperature, reducing sugar and sucrose content, and chipability. Chip manufacturing procedures, such as peeling, slice thickness and uniformity, oil type and temperature and packaging methods and materials all have a direct impact on potato chip quality (Ohio State University, 2002).
The quality of chips is determined by appearance, color, taste/ flavor, texture, moisture content, oil content and nutritional value. Color is by far the most important quality characteristic followed by oil content (Hesen, 1991).
Influence of Production Site to Processing Quality of Potatoes
Experiments have shown a high effect of the factor “site” on the suitability for processing of different potato varieties in organic farming. The results of these experiments confirm the influence of site of production on the quality of potatoes for processing (FAL, 2005).
The sugar content of potatoes is affected by the climatic factors in a location, such as temperature during growth, minimal nutrition, and irrigation (Kumar
The amount of sucrose found in potatoes at harvest is influenced by planting date, growing location, soil fertility, water availability, and any stress-inducing event (Campbell and Bagley, 2006).
Specific gravity of tubers is influenced by the cultural management of farmers in a location. Specific gravity generally decreases with reduced water application and increased available nitrogen (Ojala
The variation in specific gravity, yield and percent yield of large size tubers may be caused by cultivation practice, climatic condition, time of planting and harvesting, location, etc. Hence, it is necessary to grow the selected clones at several locations for further evaluation of processing quality, specific gravity, yield, and percent yield of large size tubers (Tantidham
Both the specific gravity and the dry matter content varied with the variety and the location of production. Such variation has been reported for many varieties grown in other countries (Verma, 1991).
Organic Farming in Potatoes
. In selecting varieties for organic potato production, varieties suited to organic production and those which best suit the intended market should be selected and grown (Dep’t of Agriculture for Northern Ireland, 1996).
. Potato plants are easy to grow, but they aren’t the easiest to grow using organic methods. Potatoes are prone to quite a few insect pests and diseases that can be a challenge to manage organically (Grubinger, 2005). Thus, organic potatoes must be a part of an overall rotation. This will involve building up of soil fertility and then exploiting that fertility with a nutrient-demanding crop such as potatoes. Legumes must be included in the rotation to provide nitrogen. Without adequate nitrogen being available, the potato crop will yield very poorly (Walsh, 2001).
. Potato growth depends on a supply of plant nutrients, such as nitrogen, phosphorus, and potassium. Each of these nutrients has specific functions for the growth and development of potato plants (Vander Zaag, 1981). Based on the results of some studies, combined potassium (K) and organic nitrogen (N) was found to be the most efficient fertilizer to increase yield for crisp and french fry production (Haase, 2005).
Quality of Organically Grown Potatoes
Organically grown foods provide more nutrients than conventionally grown foods. A recent study conducted by the Organic Center for Education and Promotion found that organically grown foods contained on average 30% more antioxidants than their conventional counterparts. A higher intake of antioxidants has been shown to have a protective effect against development of cancer, coronary heart disease, and cataracts (Lang, 2005).
In addition, glycoalkaloids (natural protective agents in potato plants and tubers) and levels of potassium, magnesium, phosphorus, and sulfur were found to be higher in organic potatoes (Martin, 2005). Vitamin C may be higher as well in organically grown produce (Finesilver, 1989).
Organically grown food also has higher dry matter content with a small number of results showing them to be lower (Finesilver, 1989).
In terms of taste, potatoes grown organically obtained significantly higher mean taste scores than conventionally grown after 6 months storage when tested blindly by a panel (Finesilver, 1989). This difference may be explained by the presence of glycoalkaloids which are higher in organic potatoes. Glycoalkaloids are thought to move from outer (such as skin) to inner (such as flesh) layers of potatoes during boiling and responsible for the perceived flavor differences (Martin, 2005).
Comparison between Conventional and Organically Grown Potatoes
. Conventional fertilizing practices such as increased application of synthetic N fertilizers may possibly result in higher crude protein concentration in plant foods but poorer quality protein than organic practices (Finesilver, 1989).
. Organically grown foods have fewer pesticide residues than conventionally grown foods. Pesticide residues were found on 23% of organic foods and 73% of conventional foods. When incidences of DDT and other banned pesticides were removed, the incidence on organically grown foods fell to 13%, but only to 71% on the conventional crops. This result indicates that roughly half of the incidence of residue found on organically grown foods is due to the persistence of past pesticide use. The incidences of residue found on conventionally grown produce were due to current applications (Lang, 2005).
. Yields on organic farms are found to be lower than yields on conventional farms, in large part because of damage by insects and diseases, but profits are higher because organic potato prices are higher than conventional prices. However, even with the price premium, good organic growing practices are needed in order to assure decent marketable yields (Grubinger, 2005).
Organically grown products are on the average 57% more expensive than conventionally grown ones. However, the higher cost is balanced by the benefits of organically grown foods (Lang, 2005).
Statistical Tool Used to Analyze Sensory Evaluation of Processed Products
Data of sensory evaluation for chips and French fries were statistically analyzed using a General Linear Model (GLM) procedure of SAS Institute. Least Significant Difference (LSD) at P
0.05 was used to separate treatment means (Tawfik
Computation of data for chip color was carried out using the multiple linear regression analysis program (32 regression). The results of this computation (coefficient of multiple correlation and regression equation) indicate that these equations provide reasonably good prediction of the chip color of individual potato cultivars (Mazza, 1983).
SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS
The chip quality of nine potato accessions grown organically in different production sites was evaluated. The organically grown potato accession with the best chipping quality and the effect of different production sites to chipping quality were identified.
The cultural management practices of the organic farmers, relative humidity and temperature, and soil properties in each site were also identified. It was observed that each of these factors had a contributory effect to the quality of the processed chips. For instance, dry matter and sugar content of potato tubers, which are critical quality factors for processing potatoes, are directly affected by relative humidity and temperature of the site.
Potatoes from Longlong produced the highest yield. Highest dry matter content and specific gravity were also observed from potatoes harvested from Balili and Englandad, respectively. Lowest sugar content, on the other hand, was exhibited by potatoes harvested from Sinipsip which might be due to the low temperature of the site.
Potatoes harvested from Balili produced the highest chip recovery but comparable with those harvested from Englandad, Longlong, and Cabutotan. Light yellow chips with slight to no browning were produced from potatoes harvested in Longlong, Balili, and Cabutotan. Chips which were processed from potatoes harvested at Balili were liked much by panelists while those processed from potatoes in Sinipsip were liked slightly.
Accession 13.1.1 had the highest yield while 285411.22 produced the lowest yield per plant. Accession 676089, on the other hand, had the highest dry matter content but comparable with those of accessions 573275, 22.214.171.124, and 13.1.1. Accession 126.96.36.199 had the highest specific gravity while the lowest sugar content was measured from accession 380251.17.
Accession 676070 also had the highest chip recovery but was comparable with most of the accessions. Light yellow chips with slight to no browning were produced by most of the accessions. In addition, the chips were moderately crispy to crispy, moderately oily, and were liked moderately by panelists.
Production site and potato accession interacted significantly to affect dry matter content, specific gravity, and sugar content. A significant interaction is also observed on the chip recovery and chip color of potato tubers . This interaction means that both site and accession are important considerations in organic growing of potatoes for chipping.
Balili is a good site for organic potato production intended for processing since it consistently produced potatoes with good chip quality. Potatoes harvested from Balili had one of the highest yield, dry matter content, specific gravity, and chip recovery. Furthermore, potatoes from Balili had one of the lowest sugar content, thus, producing light yellow chips with no browning. The chips were also liked much by the panelists. Thus, conditions in Balili might have positively influenced or enhanced the characteristics of the potato accessions for chipping.
Longlong and Cabutotan might also be excellent sites for organic potato production intended for processing since potatoes harvested from the sites showed good chipping quality. The potatoes also had high yield and high chip recovery. Moreover, the chips produced were light yellow but were liked moderately by panelists.
Among the potato accessions, accession 13.1.1 consistently showed traits indicating good chip quality. It significantly produced the highest yield in most production sites which might indicate adaptability to organic production and to the local conditions of the sites. Furthermore, accession 13.1.1 had one of the highest dry matter content, specific gravity, and chip recovery. It also had one of the lowest sugar content, thus, producing light yellow chips with no browning.
Accession 188.8.131.52 also exhibited good chip quality since it had high dry matter content, specific gravity, and chip recovery. It also produced light yellow and crispy chips. However, 184.108.40.206 produced one of the lowest yields per plant, which might discourage organic farmers from growing it.
Accession 13.1.1 planted in Balili might therefore be the best treatment combination in producing tubers with good chip quality.
Based on the results of the study, accessions 13.1.1 and 220.127.116.11 are recommended for chip processing. Balili, Longlong, and Cabutotan may also be recommended for organic production of potato accessions suitable for chip processing.
Further evaluation of potato accessions for chipping using more efficient equipments such as fryers and chippers is also recommended for more accurate results.
Finally, development of standard organic practices for potato production is also recommended. Doing this will make evaluation of the adaptability and chipping quality of potato accessions more accurate.
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