MSU Extension Publication Archive Archive copy of publication, do not use for current recommendations. Up-to-date information about many topics can be obtained from your local Extension office. Consumer Preference Tests for Dehydrofreezing and Explosive – Puffing of Blueberries Michigan State University Agricultural Experiment Station and Cooperative Extension Service Research Report Dennis S. Isidro, W. S. Greig, Henry Larzelere, Agricultural Economics; C. L. Bedford, Food Science Issued October 1964 6 pages The PDF file was provided courtesy of the Michigan State University Library Scroll down to view the publication. ~? (~ - ' . ~ ( ( ~ I"" REPORT 20 BUSINESS FROM THE MICHIGAN STATE UNIVERSITY AGRICULTURAL EXPERIMENT STATION EAST LANSING Consumer Preference Tests for Oehydrofreezing and Explosive -Puffing of Blueberries! By DENNIS S. ISIDRO, W. S. GREIG, C. L. BEDFORD and HENRY LARZELERE2 Introduction The Technologies of Dehydrofreezing ICHIGAN IS ONE of the principal producers of culti­ and Explosive-Puffing M vated blueberries in the U.S. The production of Dehydrofreezing is a method of food preservation blueberries, in Michigan and nationally, has increased which involves drying the commodity to approximately significantly over the past three decades. Projections 50 percent of fresh weight and volume before freezing indicate a continued increase in Michigan's production (11 , 12). The main objective of this processing method over the next several years. Total per capita consump­ is the reduction of weight and bulk of the product tion of both fresh and processed blueberries is increas­ while maintaining product quality (2, 13). As a result ing and consumption is concentrated relatively near to of the reduced weight and bulk; packaging, storage, areas of production. and shipping costs are also reduced (14). In addition, Over half of the total blueberry crop is processed, reduction of drip upon thawing and the ease of con­ and the principal uses of the processed products are trolling the moisture content are advantages of in pies and blueberry muffins. Blueberries are rela­ dehydrofrozen products over items frozen by the tively higher priced than most fruits used in pie form, regular method. and limited data would suggest a relatively high elas­ Though plant investment for dehydrofreezing tech­ ticity of demand for fruit pies. There is no doubt that nology is higher than for freezing, the difference in improved, cost-reducing technologie could increase cost is more than offset by the reduction in packaging, the sales of blueberry products. storage, and transportation costs of the processed Objective products. In effect, the objective of dehydrofreezing This is a progress report on the feasibility of using is to obtain some of the economies of dehydration while maintaining the quality of the frozen product. products from two new cost reducing processing Dehydrofreezing has been applied to peas (22), apples methods for blueberries-the dehydrofreezing process (23), and apricots (18). and the explosive-puffing process. The feasibility of using products from these new processes was tested Explosive-puffing is a new process developed at the by quality comparisons to standard product forms Department of Agriculture's Eastern Utilization Re­ through a consumer preference panel. search and Development Division near Philadelphia 1 This project was partially financed by the M ichigan Blueberry Grow­ ers Association. (3). It produces relatively larger dehydrated fruit and " Authors are, respectively : Graduate student and Associate Professor, vegetable pieces that can be dehydrated and rehy­ Departmcnt of Agricultural Economics; Professor, Department of Food Science; and Associate Professor, Department of Agricultural Economics. drated more rapidly than those from conventional de- 1 hydration processes. Eisenhardt describes this new The Consumer Panel process: The consumer preference tests were conducted «The vegetable or fruit pieces are partially de­ through the Michigan State University consumer hydrated in a conventional manner and heated preference panel in Detroit. Both the selection and in a closed vessel having a quick-opening lid. composition of the consumer panel members and the When the water contained within the pieces is methodologies employed in consumer preference and heated above its atmospheric boiling point and triangle tests have been described in previous reports pressure has thereby developed within the cham­ (16, 10, 9). The consumers were chosen at random ber, the pieces are instantly discharged. The flash­ from the Detroit telephone directory. The members ing of water vapor from within each piece creates of the panel were consumers with annual income rang­ a porous structure that permits much faster de­ ing from $4,000 to $10,000, of ages 30 to 45, and with hydration and much more rapid rehydration of 12 to 13 years of formal education. A subsample of the dried product (5)." 120 to 180 consumers from the above selected con­ sumers composed the Michigan State University con­ Explosion-puffing has been successfully applied on sumer panels for the tests of blueberry products. a pilot plant scale to white potatoes, sweet potatoes (21), carrots and beets (4), as well as to apple slices and Experimental Procedure and Results blueberries (6). The quick-cooking dehydrated prod­ Test I. Dehydrofrozen Blueberry Pies - A Rank Test ucts, depending on the commodity, can be rehydrated Consumer preference tests were conducted among for use in from 2-5 minutes in contrast to 30 minutes samples of blueberry pies made from normally frozen to an hour frequently required for vegetable pieces and dehydrofrozen blueberries. of the same size. The pie fillings were prepared by simmering de­ Quick-cooking dehydrated fruits and vegetables hydrofrozen blueberries in water and adding a com­ have certain advantages over canned and frozen prod­ mercial recipe of sugar, cornstarch, salt, lemon juice, ucts.;: a) The dehydrated products have less weight and butter. Pie fillings, about 20 ounces each, were and hulk and therefore storage, shipping, and packag­ placed in 9-inch aluminum pans and covered with pie ing costs are reduced. b) Larger fruits and vegetable crust. The pies were wrapped in aluminum foil, frozen, pieces are rehydrated? More easily, better, and faster. stored and subsequently baked before each consumer preference panel test was to be conducted. Each of these two new processing techniques (de­ The four types of blueberries which were used in hydrofreezing and the explosive-puffing process) yield the preparation of the pie fillings were processed and products which might be adaptable for use in many treated as follows: types of blueberry products: i.e., for use in pies, muf­ 1) for control, the hlueherries were frozen in a fins, muffin and pancake mixes, tarts, jellies and jams, normal fashion. etc. However, each of the test products were pro­ 2) for dehydrofrozen control, the blueberries were duced under laboratory conditions and only limited dried at 160°F to 50 percent of their original weight quantities of products were available. Therefore, each and volume and then were frozen at -5 °F. new product type was primarily tested against stand­ 3) for dehydrofrozen nicked, -I the blueberries were ard products in only one final-use form. The quick­ rolled over a plate, under slight pressure with razor cooking dehydrated blueberries from the explosive­ sharp triangular blades protruding sufficiently high puffing process were tested against canned ones in to cut through the skin. After this treatment, the ber­ blueberry muffin form and the dehydrofrozen ones ries were dried to 50 percent of their original weight were tested against normally frozen blueberries in and volume and then frozen at -5°F. pie form. 4) for the dehydrofrozen pricked, the blueberries Dehydrofrozen blueberry samples were prepared were rolled over a needle board so that the pin size by Dr. Clifford Bedford, Department of Food Science, holes were made in the skin. After this treatment, the Michigan State University, and quick-cooking dehy­ berries were dried to 50 percent of their original drated blueberry samples by Eastern Utilization Re­ weight and volume and then frozen at _5 °F. search and Development Division, USDA, Philadel­ In the first test, consumers ranked coded samples phia, Pennsylvania. The blueberry muffins were baked of each type of blueberry pie according to preference by the Department of Home Economics, Michigan from 1, highest, to 4, lowest. The consumers were State University and the pies hy a commercial bakery not asked the reasons for their preference. Panel in Detroit. members were served IJs of a 9-inch pie from each type. :J The process is referred to as "explosive-puffing process" while the 4 The "nicking" and "pricking" treatments were d esigned to alleviate processed product as "quick-cooking." "skin toughness" problems sometimes associated with frozen blueberries. 2 Of the 146 consumers, 64 percent gave first prefer­ TABLE 2-TRIANGLE TEST OF BLUEBERRY PIES MADE FROM DEHYDROFROZEN CONTROL AND ence to the pie made of normally frozen blueberries; DEHYDROFROZEN PRICKED BLUEBERRY PIE FIL­ dehydrofrozen control, 8 percent; dehydrofrozen LINGS, 139 CONSUMERS, DETROIT, MICHIGAN, FEBRUARY 19, 1963 a II nicked, 14 percent; and dehydrofrozen pricked, 14 Total consumers participating 139 percent (Table 1). could not differentiate products 69 A statistical analysis of results of the ranking test correctly differentiated between products