Physical and textural characteristics of some North American shortenings

A number of North American vegetable and animal fat shortenings were evaluated for their melting, crystallization, textural and polymorphic crystal characteristics and solid fat content (SFC). The majority of the dropping points and crystallization temperatures of the fats ranged from 42 to 46°C and from 27 to 31°C, respectively. Softening points of the products were higher than the dropping points of their fats, especially for the vegetable shortenings. Differential scanning calorimetry melting curves of the products were different for the various products. The animal fat shortenings were mainly in theβ-polymorphic form, while vegetable shortenings containing palm oil were in theβ′ form. Textural evaluation was carried out on the products with the cone penetrometer, constant speed penetration and constant speed compression. Constant speed compression supplied a measure of brittleness and a degree of viscosity. Lard and shortenings containing high levels of palm oil were able to withstand large deformations without breakage. The effect of tempering temperature of the fat in the SFC determination was evaluated and the values obtained were compared with the SFC of the actual product. SFC of fat and product were determined by pulse nuclear magnetic resonance. Correlation of values within textural methods was significant (P<..01), but were not significant between texture and SFC of the fat, indicating that the nature of the crystal network also plays a role in texture.     

Chemical and physical properties of the solid fats in commercial soft margarines

The fats of ten Canadian soft margarines were crystallized from acetone at 15°C to obtain the high-melting glycerides (HMG). The solid fats in the margarines were extracted with isboutanol at 5°C. X-ray diffraction showed that the canola margarines were in the β crystal form, the soybean and sunflower-palm-palm kernel margarines in the β′ form, while those of canola-palm and another sunflower-palm-palm kernel margarines contained a mixture of β′ and β forms. X-ray diffraction of the isolated solids showed additional short spacings compared with those of the original margarines. Differential scanning calorimetry heating curves of the solids were compared with those of the HMG. The melting temperatures of the HMG were 10°C higher than the solids. It is suggested that the polymorphic behavior of soft margarines is related to the chemical composition of the HMG and the solids. Solids in margarines can also be provided by interesterification of palm oil products. Presented at the Annual Meeting, Canadian section of AOCS, October 18–19, 1990, Toronto, Canada.     

Physical Properties of <Emphasis Type="Italic">trans</Emphasis>-Free Bakery Shortening Produced by Lipase-Catalyzed Interesterification

Lipase-catalyzed interesterified solid fat was produced with fully hydrogenated soybean oil (FHSBO), and rapeseed oil (RSO) and palm stearin (PS) in a weight ratio of 15:20:65, 15:40:45 and 15:50:35. The interesterified fats contained palmitic (27.8–44.6%), stearic (15.6–16.2%), oleic (27.5–36.5%) and linoleic acids (8.0–13.5%). After interesterification of the blends, the physical properties of the products changed and showed lower melting points and solid fat contents, different melting and crystallization behaviors as well as the formation of more stable crystals. The produced interesterified fats (FHSBO:RSO:PS 15:20:65, 15:40:45 and 15:50:35 blends) contained desirable crystal polymorphism (β′ form) as determined by X-ray diffraction spectroscopy, a long plastic range with solid fat content of 51–63% at 10 °C to 4–12% at 40 °C, and melting points of 39 (15:50:35), 42 (15:50:45) and 45 °C (15:20:65). However, a reduction in tocopherols (α and γ) content and a reduced oxidative stability were observed in the interesterified fats. The physical properties of the interesterifed fats were influenced by the amount of PS, resulting in more hardness and higher solid fat contents for 15:20:65 than 15:40:45 and 15:50:35 blends. The present study suggested that the produced interesterified fats containing trans-free fatty acids could be used as alternatives to hydrogenated types of bakery shortenings.     

Physical and chemical properties of trans-free fats produced by chemical interesterification of vegetable oil blends

Fat blends, formulated by mixing a highly saturated fat (palm stearin or fully hydrogenated soybean oil) with a native vegetable oil (soybean oil) in different ratios from 10:90 to 75:25 (wt%), were subjected to chemical interesterification reactions on laboratory scale (0.2% sodium methoxide catalyst, time=90 min, temperature=90°C). Starting and interesterified blends were investigated for triglyceride composition, solid fat content, free fatty acid content, and trans fatty acid (TFA) levels. Obtained values were compared to those of low- and high-trans commercial food fats. The interesterified blends with 30–50% of hard stock had plasticity curves in the range of commercial shortenings and stick-type margarines, while interesterified blends with 20% hard stock were suitable for use in soft tubtype margarines. Confectionery fat basestocks could be prepared from interesterified fat blends with 40% palm stearin or 25% fully hydrogenated soybean oil. TFA levels of interesterified blends were low (0.1%) compared to 1.3–12.1% in commercial food fats. Presented at the 88th AOCS Annual Meeting and Expo, May 11–14, 1997, Seattle, Washington.     

Trans-free bakery shortenings from mango kernel and mahua fats by fractionation and blending

Bakery shortenings prepared by hydrogenation contain high levels of trans fatty acids, which are considered to be risk factors for cardiovascular disease. The shortenings prepared from maogo kernel and mahua fats have no trans fatty acids. Mahua fat was fractionated by dry fractionation to obtain a high-melting fraction (10% yield, Mh1). Mango fat was fractionated by two-stage solvent fractionation, separating about 15% high-melting fraction (Mk1) in the first stage, followed by 40% stearin (Mk2) in the second stage. The formulation containing 80% Mh1 and 20% of mango middle stearin fraction (Mk2) showed melting characteristics and onset and enthalpy of crystallization similar to those of commercial hydrogenated shortenings designed for cakes and biscuits. The formulation suitable for puff pastry shortening was prepared by blending 50% mango 1st stearin (Mk1) and 50% mahua fat with addition of 5–7% of fully hydrogenated vegetable oil. The formulations having melting characteristics similar to those of commercial cake and biscuit shortenings were also prepared by blending 40% mango fat and 60% mahua fat with 5–7% incorporation of fully hydrogenated peanut oil. However, these formulations showed delayed transition to the stable forms compared to those of commercial samples. Fatty acid composition revealed that commercial hydrogenated shortenings consisted of 18–29% trans oleic acid, whereas the formulations we prepared did not contain any trans acids. The iodine values of commercial samples were 57–58, whereas the value for the formulations prepared were 47–53. The consistency of the prepared samples as measured by cone penetrometer was slightly harder than commercial samples. These studies showed that it is possible to prepare bakery shortenings with no trans fatty acids by using mango and mahua fats and their fractions.     

Fatty acid composition of spanish shortenings with special emphasis on <Emphasis Type="Italic">trans</Emphasis> unsaturation content as determined by fourier transform infrared spectroscopy and gas chromatography

A Fourier transform infrared spectroscopic procedure was used to analyze 34 edible fats (22 shortenings and 12 vegetable margarines) as neat fats (IR_NF) to determine their total trans fatty acid (TFA) content. The sloping baseline was corrected with a reference spectrum based on a nonprocessed olive oil. The calibration was done using seven partially hydrogenated fats with an individual TFA content previously determined by the combination of gas chromatography (GC) with argentation thin-layer chromatography. Taking into account the different absorptivities of various trans isomers, different correction factors were calculated using the calibration standards (0.83 and 1.71 for single trans bonds in both diethylene and triethylene and for trans, trans-diethylene fatty acids, respectively) and applied to calculate the total TFA of samples. Moreover, the samples were converted to their methyl esters and reanalyzed following the same procedure (IR_FAME). Differences in TFA content of fats were not found when a t-test was used to compare the results obtained by IR_NF vs. either IR_FAME or GC, suggesting that IR of neat fats could be used, thus avoiding the need to prepare sample solutions in organic solvents and to prepare fatty acid methyl esters. The mean TFA content (determined by IR_NF) of a representative group of Spanish shortenings (22 samples) that varied widely in terms of fat sources, processes, and purposes (bakery, sandwiches, ice cream, coatings, chocolate coverings) was 6.55±11.40%, although more than 54% contained <3% of TFA. Fatty acid composition of shortenings by direct GC using a 100-m polar cyanopolysiloxane capillary column indicated that the mean trans-18∶2 isomer content was 0.58%, ranging from 0.9 to 3.4%. Small amounts of trans-18∶3 isomers (<0.3%) were observed in 18 of the 22 shortenings studied; the maximal value was <2%. The mean value of the fraction saturated+TFA of shortenings was high (59.95±12.73%), including two values higher than 83%.     

A review of rapeseed oil uses for edible purposes

Food technological aspects on the use of rape-seed oil and otherCruciferae seed oils as salad oils, in margarine, shortenings and some other foods are briefly reviewed. It is concluded that these oils in hydrogenated or nonhydrogenated form may compete favorably with other vegetable oils and animal fats. One of nine papers published from the Symposium, “Cruciferous Oilseeds,” ISF-AOCS World Congress, Chicago, September 1970.     

Relationship between rancimat and active oxygen method values at varying temperatures for several oils and fats

Determination of oxidative stability of different edible oils, fats, and typical fat products was made using the Rancimat method and the active oxygen method. Induction periods (IP) were recorded under controlled conditions at 110, 120, and 130 ± 0.1°C for all products and over a range of 100–160°C for selected fats. A general oil stability evaluation industrial shortenings and vanaspati to be the most stable fats, with IP ranging from 10.00 to 15.47 h. Margarine and butter samples (IP, 4.98–6.04 h) were also found to show fair oxidative stability. Among the extracted and open-market salad-grade cooking oils, rapeseed oil (IP, 4.10 h) and soybean oil (IP, 4.00 h) showed the highest oxidative stability, whereas Salicornia bigelovii oil (IP, 1.40 h) was the least stable. The induction periods of typical fat products ranged from 2.59 to 9.20 h. CV for four determinations were <5.2% for shortening and vanaspati products and <4.3% for various vegetable oils, margarine, butter, and typical fat products. Rancimat IP values obtained at 110, 120, and 130°C were 40–46, 20–25, and 9–13% of active oxygen method values, respectively, corresponding to a decrease in Rancimat IP by a factor of 1.99 with each 10°C increase in temperature. Similarly, in the temperature range 100–160°C, an increase of 10°C decreased the Rancimat IP by a factor of 1.99     

Low-<Emphasis Type="Italic">trans</Emphasis> Shortening and Spread Fats Produced by Electrochemical Hydrogenation

Partially hydrogenated soybean oils (90–110 IV) were prepared by electrochemical hydrogenation at a palladium/cobalt or palladium/iron cathode, moderate temperature (70–90 °C) and atmospheric pressure. The trans fatty acid (TFA) contents of 90–110 IV products ranged from 6.4 to13.8% and the amounts of stearic acid ranged from 8.8 to 15.4% (the higher stearic acid contents indicated that some reaction selectivity had been lost). The solid fat values and melting point data indicated that electrochemical hydrogenation provides a route to low-trans spreads and baking shortenings. Shortenings produced by conventional hydrogenation contain 12–25% trans fatty acids and up to 37% saturates, whereas shortening fats produced electrochemically had reduced TFA and saturate content. Electrochemical hydrogenation is also a promising route to low-trans spread and liquid margarine oils. Compared to commercial margarine/spread oils containing 8–12% TFA, the use of electrochemical hydrogenation results in about 4% TFA. Names are necessary to report factually an available data: the USDA neither guarantees nor warrants the standard of the product, and the use of the name USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Preparation of plastic fats with zero <Emphasis Type="Italic">trans</Emphasis> FA from palm oil

A series of plastic fats containing no trans FA and having varying melting or plastic ranges, suitable for use in bakery, margarines, and for cooking purposes as vanaspati, were prepared from palm oil. The process of fractionating palm oil under different conditions by dry and solvent fractionation processes produced stearins of different yields. Melting characteristics of stearin fractions varied depending on the yield and the process. The lower-yield stearins were harder and had a wider plastic range than those of higher yields. The fractions with yields of about 35% had melting profiles similar to those of commercial vanaspati. The plastic range of palm stearins was further improved by blending them with corresponding oleins and with other vegetable oils. The plasticity or solid fat content varied depending on the proportion of stearin. Blends with higher proportions of stearins were harder than those with lower proportions. the melting profiles of some blends, especially those containing 40–60% stearin of about 25% yield and 40–60% corresponding oleins or mahua or rice bran oils, were similar to those of commercial vanaspati and bakery shortenings. These formulations did not contain any trans FA, unlike those of commercial hydrogenated fats. Thus, by fractionation and blending, plastic fats with no trans acids could be prepared for different purposes to replace hydrogenated fats, and palm oil could be utilized to the maximum extent.     

The Production of an Experimental Table Margarine Enriched with Conjugated Linoleic Acid (CLA): Physical Properties

Even though conjugated linoleic acid (CLA) is known to have some beneficial effects on the human body, its consumption has decreased over the past 20 years due to the replacement of animal fats by vegetable oils. In this study, using the structured lipid (SL) containing CLA, an experimental table margarine enriched with CLA was produced and stored for 3 months at two temperatures prior to performing the relevant analyses. The GC results showed that the margarine fat had 10.6% CLA. The solid fat content was the highest in week 0 in all samples, which then decreased during storage but the hardness increased. An increment in dropping point was also observed in the samples. In week 0, all the samples had the β′ crystal as the predominant crystal form but a crystal transformation from β′ to β was observed during storage.     

Regulating the β′→β polymorphic transition in food fats

Hydrogenated cottonseed oil (HCSO) is commonly used as a β′-stable fat in margarines and shortenings. In the present study, the crystallization behavior of HCSO is altered via dilution, agitation, tempering regime, and the addition of an emulsifier [polyglycerol polyricinoleate (PgPr)]. Key properties assessed include crystal morphology (with polarized light microscopy), polymorphic behavior (with X-ray diffraction), and crystallization kinetics (with DSC). It is demonstrated that on considerable dilution with canola oil (4% w/w), HCSO can be crystallized in the β′ or β polymorph with associated changes in crystal morphology, depending on tempering regime. Crystallization from the melt to 25°C results in the β′-form, as there is insufficient supercooling to form the β polymorph but enough to form the metastable β′. With cooling from the melt to 5°C, there is adequate supercooling for the δ polymorph to form, with the presence of the canola oil facilitating the transformation toward this stable phase. Static vs. crystallization under agitation does not lead to visible changes in either polymorphic behavior or crystal morphology. However, there is extensive secondary nucleation and growth as a result of crystals breaking off accreting agglomerates. The presence of PgPr, added as a crystal modifier, does not affect the final crystal polymorph or morphology, except under one set of conditions—crystallization from the melt to 5°C with agitation, whereby it considerably alters crystallization behavior.     

Chemical and physical properties of the high melting glyceride fractions of commercial margarines

The fat obtained from nine commercial mar-garines purchased from Canada and the U.S.A. were crystallized from acetone at 15, 10, 5 and 0°C. The high melting triglyceride (HMG) fractions at 15°C contained high levels of palmitic and stearic acids. The 18:1 levels increased as fractionation temperature decreased. Triglyceride analysis re-vealed that the 11MG fractions contained high 1ev-els of carbon 54 and 52. The levels of trans iso-mers increased, whereas the trans levels in the 18:1 decreased with fractionation temperature. Mar-games made from canola oil exhibited β charac-teristics whereas canola-paim, soybean and corn margarines showed β¹ crystals. The fractions as crystallized from acetone, showed numerous X-ray short spacings, characteristic of β¹, β and in-termediate forms. Upon heating and cooling, the 15°C fraction showed β¹ or a and β¹ characteris-tics regardless of the polymorphic form present in the original margarines. The differential scan-ning calorimetry (DSC) melting points of these fractions varied from 53 to 50° C. The difference between the β and β¹ margarines could be related to the 16:0 and carbon 54 content of the 15°C frac-tion. In the β tending margarines the 16:0 content was below 11%, in the β¹ tending margarines above 17%. The carbon 54 content in the 15°C fraction of the β tending margarines was close to 70% and that of the β¹ tending margarines around 50%. The triglyceride C54 in the 15°C fraction is β tending and therefore should be kept as low as possible. In canola margarines this can be achieved by in-corporation of palm oil, preferably in a slightly hydrogenated form. Presented at the Annual Meeting, Canadian Section of AOCS, October, 1989, Halifax, Canada.     

Zero-<Emphasis Type="Italic">trans</Emphasis> shortening using palm stearin and rice bran oil

Several pilot-scale trials reported in this paper, using palm stearin-rice bran oil (PS-RBO) blends, obviously did not contain trans FA (TFA), whereas the commercial products were found to contain 18–27% TFA. The effects of processing conditions such as rate of agitation, crystallization temperature, and composition of the blends on the crystal structure of shortenings were studied. The products were evaluated for their physicochemical characteristics using DSC, X-ray diffraction (XRD), HPLC, and FTIR techniques. The formulation containing 50% PS and 50% RBO showed melting and cooling characteristics similar to those of hydrogenated commercial “vanaspati” samples. Analysis of the FA composition revealed that the formulated shortenings contained 15–19% C_18∶2 PUFA. Tocopherol and tocotrienol contents of the experimental shortenings were in the range of 850–1000 ppm with oryzanol content up to 0.6%. XRD studies demonstrated that the crystal form in the shortenings was predominantly the most stable β′ form, and there was less of the undesirable β form.     

Polymorphic behavior of high-melting glycerides from hydrogenated canola oil

Canola oil was hydrogenated with a commercial nickel catalyst at 175°C and 15 psi hydrogen pressure. Samples were taken during the reaction starting at 15 min and thereafter at ten-minute intervals. The reaction was stopped after two hours. The high-melting glycerides (HMG) were obtained by fractional crystallization at 15°C with acetone as solvent. The HMG were analyzed for fatty acid and triglyceride composition by gas liquid chromatography andtrans was determined by infrared spectroscopy. In the first 45 min of hydrogenation of canola oil, the 18:0 fatty acid increased at a low rate while thetrans fatty acid content increased at a much faster rate. The 16:0 and 18:0 content of the HMG was highest andtrans content the lowest during the period in which the triglyceride composition was the most diverse. The 54-carbon triglyceride content of the HMG increased from 64% to 78% during the two hours of hydrogenation. The short spacings for the HMG showed the presence ofβ crystals as well as several intermediate forms. The number of short-spacings increased with hydrogenation time. The differential scanning calorimetry (DSC) melting profile of the HMG showed one broad peak between 20 and 30°C and two peaks around 60°C and above. Crystallization temperatures of the HMG were in the range of 40–45°C. Presented at the 81st American Oil Chemists' Society Annual Meeting, April, 1990, Baltimore, Maryland.     

Fatty acid (FA) composition and contents of <Emphasis Type="Italic">trans</Emphasis> unsaturated FA in hydrogenated vegetable oils and blended fats from Pakistan

This study presents the FA composition and trans FA (TFA) contents of different hydrogenated vegetable oils and blended fats marketed in Pakistan. Thirty-four vanaspati (vegetable ghee), 11 shortenings, and 11 margarines were analyzed. The contents of saturated FA, cis monounsaturated FA, and cis PUFA were in the following ranges: vanaspati 27.8–49.5, 22.2–27.5, 9.3–13.1%; vegetable shortenings 37.1–55.5, 15.8–36.0, 2.7–7.0%; and margarines 44.2–55.8, 21.7–39.9, 2.9–20.5%, respectively. Results showed significantly higher amounts of TFA in vanaspati samples, from 14.2 to 34.3%. Shortenings contained TFA proportions of 7.3–31.7%. The contents of TFA in hard-type margarines were in the range of 1.6–23.1%, whereas soft margarines contained less than 4.1% TFA.     

The use of antioxidants in potato chipping

Summary Laboratory and commercial-scale fryings of potato chips have been made with various vegetable oils, vegetable shortenings, lard, and combinations of these. Fryings have been made with and without the addition of butylated hydroxyanisole as an antioxidant. The data from both types of experiments indicates that butylated hydroxyanisole possesses “carrythrough” antioxidant properties not only in animal fats but in vegetable oils and vegetable shortenings also. Data also indicates that the addition of propyl gallate and citric acid as synergists to the butylated hydroxyanisole increases the “carry-through” antioxidant properties. Presented at 23rd Fall Meeting, American Oil Chemists’ Society, Chicago, Ill., Oct. 31, Nov. 1 and 2, 1949. The Schaal Oven Tests were conducted at 145°F.     

Interesterification of lard

The graininess, which develops at 27C (80F) in lard shortening which has not undergone interesterification, is due to large crystal aggregates of disaturated 2-palmitoyloleoylstearin (OPS) of intermediate melting level and existing in a β'-type form of triple-chain-length structure. This β'-3 phase exists in ordinary lard accompanied by the commonly reported β phase which is largely due to trisaturated glycerides. Random interesterification eliminates graininess, not by reducing the disaturated content which remains about the same, but by reducing OPS to its “random” proportion and producing a mixture of disaturated glycerides, which is substantially lower melting than the original OPS. The resulting product crystallizes typically in a β'-2 form, characteristic of hydrogenated vegetable oil shortenings. (Directed interesterification actually reduces disaturated content as well as graininess, while simultaneously creating trisaturated “hardstock.”)     

Formulation of zero-<Emphasis Type="Italic">trans</Emphasis> acid shortenings and margarines and other food fats with products of the oil palm

The fruit of the oil palm yields two types of oil. The flesh yields 20–22% of palm oil (C16∶0 44%, C18∶1 39%, C18∶2 10%). This represents about 90% of the total oil yield. The other 10%, obtained from the kernel, is a lauric acid oil similar to coconut oil. Palm oil is semisolid, and a large part of the annual Malaysian production of about 14 million tonnes is fractionated to give palm olein, which is widely used for industrial frying, and palm stearin, a valuable hard stock. Various grades of the latter are available. Formulae have been developed by straight blending and by interesterification of palm oil and palm kernel oil to produce shortenings and margarines using hydrogenated fats to give the consistency required. Products that include these formulations are cake shortenings, vanaspati (for the Indian subcontinent), soft and brick margarines, pastry margarines, and reduced fat spreads. Other food uses of palm products in vegetable-fat ice cream and cheese, salad oils, as a peanut butter stabilizer, and in confectioners fats are discussed briefly here.     

Physicochemical and Rheological Characterization of Roll-in Shortenings

The composition and physical properties of roll‐in shortenings, commonly rich in trans and saturated fatty acids, were investigated and compared to other specialty fats, to provide insights into the physico‐chemical origins of their functionality. Triacylglycerols and fatty acid composition, polymorphic and melting behavior, solid fat content and large deformation rheological properties were determined. Roll‐in shortenings contained higher amounts of trisaturated and unsaturated triacylglycerols (12–27 %; 47–62 %) than other shortenings (9–11 %; 6–44 %). However, all exhibited high levels of saturates and trans fatty acids and similar crystal characteristics: β′ or mixed β′ and β, irrespective of their end use. Roll‐in shortenings had comparable melting peaks (42–52 °C) but sharper melting endotherms with higher enthalpies (38.6–43.3 J/g) than other bakery fats (18.7–25.4 J/g). This was in accordance with their well‐defined short spacings, indicative of smaller crystallites with more‐ordered packing. Solid fat profiles of roll‐in shortenings were akin to all purpose and cake interesterified shortenings, but not to all‐purpose and icing shortenings which displayed substantial melting as temperature rises. Differences in large deformation rheology (yield stress: σ^*, apparent Young modulus: E_app, yield value: C) were marginal and inconsistent with their solid fat content. Roll‐in shortenings exhibited E_app, σ and C in the order of 1–2 × 10⁶, 4–7 × 10⁴, and 7–29 × 10⁴ Pa, respectively. Particularly, the σ*and C, previously established as major parameters to specify the functionality of roll‐in shortenings, were not significantly different (p > 0.05). Overall, roll‐in shortening differed from other samples in regard to molecular makeup but not greatly in their physical parameters, suggesting that triacylglycerol composition has important implications on their functionality.